HomeMy WebLinkAboutTile Flat Analysis Technical Memo_6-10-25 Draft
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MEMORANDUM
DATE: June 10, 2025
TO: River Terrace 2.0 Project Management Team
FROM: Adrian Witte, Toole Design and Kevin Chewuk, DKS Associates
SUBJECT: River Terrace 2.0 Community Plan
Tile Flat Extension Scenarios Evaluation
#24434-000
This memorandum summarizes the multimodal transportation analysis methodology and findings for the
evaluation of Tile Flat extension scenarios as part of the River Terrace 2.0 Community Plan. Included are the
objectives of the study, a summary of the primary street network and Tile Flat extension scenarios, the
performance metrics used to compare scenarios, and the results of the analysis, which will be used by staff to
identify a scenario to recommend to decision makers moving forward.
STUDY OBJECTIVES
The objective of the study is to compare holistic benefits, impacts, and costs of the different primary street
network scenarios and to understand and quantify if there are additional benefits to extending Tile Flat Road or
Mountainside Way beyond providing the base network identified in the River Terrace 2.0 Concept Plan.
TILE FLAT EXTENSION SCENARIOS
The team identified four primary street network scenarios to be evaluated within the River Terrace 2.0
Community Planning process – two of these extend Mountainside Way without a connection to Tile Flat Road
and two include an extension of Tile Flat Road to meet Mountainside Way.
All scenarios provide a primary north to south collector route along Mountainside Way connecting from Scholls
Ferry Road and running west of and eventually connecting to Roy Rogers Road at the Bull Mountain Road
intersection. This scenario is identified as Scenario 1.
The conceptual alignments of the primary streets for each of the four scenarios are shown on Figure 1 through
Figure 4, although the alignments could be shifted slightly to better serve the surrounding neighborhood or
provide other system benefits (e.g., to reduce costs, lessen impacts to sensitive lands, provide better
connectivity, etc.). The Tile Flat extension scenarios include:
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• Scenario 1: Includes the Mountainside Way extension from Scholls Ferry Road to the Roy Rogers Road /
Bull Mountain Road intersection (Segment A) and is shown in red on Figure 1.
• Scenario 2: Includes Segment A, plus the Tile Flat Road extension from Scholls Ferry Road to the
Mountainside Way extension (Segment B) and is shown in green on Figure 2.
• Scenario 3: Includes Segment A, plus the extension of Mountainside Way from Bull Mountain Road to
connect with Roy Rogers Road somewhere at or between the Perth Road or Woodhue Street
intersections (Segment C) and shown in blue on Figure 3.
• Scenario 4: Includes Segments A, B, and C and is shown in purple on Figure 4.
Figure 5 shows the primary street scenarios and preliminary alignments for supporting streets (assumed to be
primarily neighborhood street classifications) that react to site constraints such as existing and planned
intersections along the primary street network, jurisdictional boundaries, stream crossings, significant trees,
groves, and wetlands, fire, life, safety access requirements, and other factors. Future iterations of the street
network will further refine these assumptions and consider other factors such as alignment with school district
boundaries and parcel boundaries that could impact phasing.
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SW Lasich Ln
SW Bull Mtn Rd
SW Beef Bend Rd
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FIGURE 1 : TILE FLAT EXTENSION SCENARIO 1.
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FIGURE 2 : TILE FLAT EXTENSION SCENARIO 2 .
SW Lasich Ln
SW Bull Mtn Rd
SW Beef Bend Rd
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FIGURE 3 : TILE FLAT EXTENSION SCENARIO 3 .
SW Lasich Ln
SW Bull Mtn Rd
SW Beef Bend Rd
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FIGURE 4 : TILE FLAT EXTENSION SCENARIO 4.
SW Lasich Ln
SW Bull Mtn Rd
SW Beef Bend Rd
SW
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SW Scholls Ferry Rd
SW Jean Louise Rd
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SW Tile Flat Rd
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FIGURE 5 : PRELIMINARY RIVER TERRACE 2.0 STREET NETWORK DIAGRAM.
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PERFORMANCE METRICS
The Tile Flat extension scenarios were assessed and compared using the performance metrics shown below.
These include a mix of quantitative and qualitative considerations. Wherever possible, findings were
communicated in terms of resident and traveler experiences, with a focus on identifying meaningful differences
between scenarios.
1. Vehicular Network
A. Vehicle Miles Traveled (VMT)
B. Quantity of Travel
C. Intersection Capacity
D. Travel Time
2. Multimodal Network
A. Bicycle Level of Traffic Stress (BLTS)
B. Pedestrian Level of Traffic Stress (PLTS)
C. Connectivity
D. Vulnerable Road User Safety
E. Future Transit Service
3. Environmental / Livability
A. GHG and Emissions
B. Natural Resource Impacts
C. Livability Impacts of Regional Vehicle Trips
4. Development Feasibility
A. Support to Commercial Areas
B. Land Use and Development Feasibility
C. Order-of-Magnitude Infrastructure Costs
D. Timing, Phasing, and Project Cost
E. Fire, Life, Safety
5. Equity
A. Equitable Benefits
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1. VEHICULAR NETWORK
The following are performance metrics that compare vehicular travel between the Tile Flat extension scenarios.
A. Vehicle Miles Traveled (VMT)
Description
Analysis A1: Comparison of the vehicle miles travelled on the arterial and primary and secondary street
networks. This includes the combined VMT on arterials (i.e., Scholls Ferry Road from Tile Flat Road to Roy Rogers
Road and Roy Rogers Road from Scholls Ferry Road to Perth Road) and on primary and secondary Streets (i.e.,
Mountainside Way from Scholls Ferry Road to Roy Rogers Road, Mountainside Way from Sabrina Avenue (south)
to Perth Road and Tile Flat Road from Scholls Ferry Road to Mountainside Way).
Analysis A2: Comparison of the vehicle miles travelled on just the primary and secondary street network. This
includes the combined VMT on Mountainside Way from Scholls Ferry Road to Roy Rogers Road, Mountainside
Way from Sabrina Avenue (south) to Perth Road and Tile Flat Road from Scholls Ferry Road to Mountainside
Way.
Methodology
VMT was estimated using the forecasted motor vehicle traffic volumes along roadway segments for 2040 using
Washington County's version of the Metro Regional Transportation Demand Model. The volumes were based on
the PM peak hour and were multiplied by the length of the segment to estimate the total VMT for each
scenario.
A1: A scenario performs best if the total VMT decreases more than 1% from no-build, is neutral if there is a
change of less than 0.5% from no-build, and performs worst if there is an increase of more than 1% from no-
build.
A2: A scenario performs best if the share of total VMT for RT 2.0 trips on the primary and secondary street
network is greater than 75%, is neutral if it is between 50% and 60%, and performs worst if it is less than 25%.
Results and Evaluation
A1: Table 1 shows that the overall forecasted VMT on the arterial street network is expected to be fairly similar
for each of the scenarios. Scenarios 1 and 3 include a total estimated VMT of over 6,700 along the arterial
roadways in the River Terrace 2.0 West area, which is similar to the forecasted VMT under no-build conditions,
and that is expected to decrease between 5% and 7% with Scenarios 2 and 4.
The estimated VMT on Roy Rogers Road is expected to decrease slightly under all scenarios when compared to
Scenario 1, with traffic shifting to Mountainside Way, although some of that shift is negated by other regional
traffic shifting to Roy Rogers Road from other nearby congested arterials. The estimated VMT on Scholls Ferry
Road is expected to decrease with Scenarios 2 and 4 when compared to Scenario 1, with traffic shifting to Tile
Flat Road.
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TABLE 1 : COMPARISON OF VMT ON THE STREET NETWORK
Ideal Definition Total VMT on
the Arterial
network (PM
Peak Hour)
Total VMT on
the Primary and
Secondary
Street network
(PM Peak Hour)
Total
VMT
(PM
Peak
Hour)
Total VMT
Change
from no-
build
Total VMT decreases on the
arterial and primary and
secondary street network* as
the RT 2.0 primary and
secondary street network is
constructed and accommodates
more local trips.
Scenario 1 6,761 382 7,143 -0.5%
Scenario 2 6,397 855 7,252 1.0%
Scenario 3 6,729 420 7,149 -0.4%
Scenario 4 6,254 903 7,156 -0.3%
Notes: * Includes combined VMT on arterials (i.e., Scholls Ferry Road from Tile Flat Road to Roy Rogers Road and Roy Rogers Road
from Scholls Ferry Road to Perth Road), and on the primary and secondary street network (i.e., Mountainside Way from Scholls Ferry
Road to Roy Rogers Road, Mountainside Way from Sabrina Avenue (south) to Perth Road and Tile Flat Road from Scholls Ferry Road to
Mountainside Way).
The scenarios were ranked with the following compared to the ideal condition:
- >=1% from no-build - 0.5% - 1%
from no-
build
+ - 0.5%
from no-
build
+ 0.5% - 1%
from no-build
+ >=1% from no-build
A2: Table 2 shows that the overall forecasted VMT on the primary and secondary street network is expected to
be mostly local trips under Scenario 1, at 92%, and the share of the total VMT for local trips decreases under
Scenarios 2, 3, and 4. In Scenarios 2 and 4, regional trips account for more than 50% of the total VMT on the
primary and secondary street network, with these trips utilizing Tile Flat Road and Mountainside Way, instead of
the surrounding arterials.
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TABLE 2 : COMPARISON OF VMT ON THE PRIMARY AND SECONDARY STREET NETWORK
Ideal Definition VMT of
Regional Trips
(PM Peak Hour)
VMT of RT 2.0
Trips
(PM Peak Hour)
Share of Total
VMT for RT 2.0
Trips
The RT 2.0 primary and secondary
street network* serves local trips
and discourages regional cut-
through traffic.
Scenario 1 30 352 92%
Scenario 2 449 406 47%
Scenario 3 160 260 62%
Scenario 4 465 438 48%
Notes: * Includes combined VMT on Mountainside Way from Scholls Ferry Road to Roy Rogers Road, Mountainside Way from
Sabrina Avenue (south) to Perth Road and Tile Flat Road from Scholls Ferry Road to Mountainside Way.
The scenarios were ranked with the following compared to the ideal condition:
>=75% local
trips
60-75% local
trips
50-60% local
trips
25-50% local
trips
<=25% local
trips
B. Quantity of Travel
This performance metric compares the change in the forecasted average daily traffic (ADT) volume along the
primary and secondary street network including Mountainside Way and Tile Flat Road.
Methodology
Average daily motor vehicle volumes were forecasted along roadway segments for 2040 using Washington
County's version of the Metro Regional Transportation Demand Model. These volumes were estimated using the
PM peak hour volumes and multiplying them by a factor of 10 to represent ADT.
A scenario performs best if the forecasted ADT volume along the segment is consistent with that of a collector
street through a residential neighborhood, with the ideal condition being under 6,000 vehicles per day (vpd). A
scenario with a forecasted ADT over 6,000 vpd along a segment performs worst.
Results
Table 3 shows the forecasted 2040 ADT volume for each scenario along the primary and secondary street
network. Figure 6 through Figure 9 show the forecasted 2040 ADT volumes for the street network in the River
Terrace 2.0 area.
Scenario 1 is forecasted to have the lowest ADT volumes along the primary and secondary street network.
Scenarios 2 and 4 were found to draw trips from Scholls Ferry Road and Roy Rogers Road and increase trips on
Tile Flat Road and the segments of Mountainside Way south of where Tile Flat Road would connect, as well as
on Bull Mountain Road where it connects to Roy Rogers Road. These are street segments internal to the RT 2.0
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West development and the forecasted 2040 ADT volumes along Mountainside Way for Scenarios 2 and 4 are
forecasted to be higher than Scenarios 1 and 3.
Scenario 3 does not include the Tile Flat Road extension but extends Mountainside Way to Perth Road. It would
result in similar forecasted 2040 ADT volumes along Scholls Ferry Road and Roy Rogers Road compared to
Scenario 1, slight increases along Mountainside Way, and a reduction along Bull Mountain Road compared to
Scenario 1.
TABLE 3 : QUANTITY OF TRAVEL ON THE PRIMARY AND SECONDARY STREET NETWORK
Ideal Definition Roadway Segment Scenario 1:
ADT
Scenario 2:
ADT
Scenario 3:
ADT
Scenario 4:
ADT
Forecasted average daily
traffic volumes on the
primary and secondary
street network are
consistent with that of a
collector through a
residential neighborhood,
with the ideal condition
being under 6,000 ADT.
SW Mountainside Way
Scholls Ferry Road to
Sabrina Avenue
4,700 3,700 5,200 3,800
Sabrina Avenue (north) to
Jean Louise Road
4,000 7,000 4,500 7,600
Jean Louise Road to
Sabrina Avenue (south)
2,900 5,900 3,600 6,600
Sabrina Avenue (south) to
Perth Road
n/a n/a 2,100 3,400
SW Bull Mountain Road
Sabrina Avenue (south) to
Roy Rogers Road
3,000 5,800 1,700 3,400
SW Tile Flat Road
Roy Rogers Road to
Mountainside Way
n/a 4,000 n/a 4,500
Notes: The scenarios were ranked with the following compared to the ideal condition:
ADT <= 3,000 ADT 3,000-6,000 ADT 5,001-6,500 ADT 6,501-7,000 ADT >= 7,000
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FIGURE 6 : FORECASTED 2040 AVERAGE DAILY TRAFFIC FOR SCENARIO 1.
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FIGURE 7 : FORECASTED 2040 AVERAGE DAILY TRAFFIC FOR SCENARIO 2 .
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FIGURE 8 : FORECASTED 2040 AVERAGE DAILY TRAFFIC FOR SCENARIO 3 .
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FIGURE 9 : FORECASTED 2040 AVERAGE DAILY TRAFFIC FOR SCENARIO 4 .
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C. Intersection Capacity
This metric compares the traffic operational performance at surrounding intersections along the arterial
network on Scholls Ferry Road and Roy Rogers Road.
Methodology
The Highway Capacity Manual 6th Edition methodology was used to calculate volume-to-capacity (v/c) ratios at
intersections for the weekday PM peak hour.
A scenario performs best if the intersection is forecasted to operate with a v/c ratio that is at or below the
current mobility target and performs worst if it operates higher than it.
Results
As shown in Table 4, the intersections are forecasted to operate with similar v/c ratios under each scenario. The
Mountainside Way extension to Perth Road included in Scenario 3, and when both it and the Tile Flat Road
extension are combined under Scenario 4 allows for a slight improvement in forecasted operations at
intersections along Scholls Ferry Road and at the Roy Rogers Road & Jean Louise Drive intersection.
TABLE 4 : INTERSECTION OPERATIONS (2040 PM PEAK)
Ideal Definition Intersection Volume-to-Capacity (V/C) Ratio
Scenario 1 Scenario 2 Scenario 3 Scenario 4
Intersections are
forecasted to be less
congested once the
RT 2.0 Primary and
Secondary Street
network is
constructed, with
intersections
forecasted to
operate with a v/c
ratio that is at or
below the current
0.99 mobility target.
SW Scholls Ferry Road/
SW Tile Flat Road
0.97 0.85 0.97 0.85
SW Scholls Ferry Road/
SW Mountainside Way
0.97 0.53 0.58 0.53
SW Scholls Ferry Road/
SW Roy Rogers Road/
SW 175th Avenue
1.16* 1.21* 1.16* 1.21*
SW Roy Rogers Road/
SW Jean Louise Road
0.93 0.92 0.89 0.91
SW Roy Rogers Road/
SW Bull Mountain Road
0.96 1.01* 0.93 0.98
SW Roy Rogers Road/
SW Perth Road
0.86 0.88 0.97 0.99
Notes: * Indicates an intersection that is forecasted to operate above the current mobility target of 0.99 v/c.
The scenarios were ranked with the following compared to the ideal condition:
v/c <=0.99 v/c 1.00-1.05 v/c 1.06-1.10 v/c 1.11-1.15 v/c >= 1.16
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The scenarios also alter turning movement patterns at intersections along Roy Rogers Road. Scenarios 2 and 4,
that extend Tile Flat Road to Mountainside Way, add traffic to Bull Mountain Road, which results in slight
degradation of forecasted operations at the Roy Rogers Road intersection. Scenario 3 that extends
Mountainside Way to Perth Road draws traffic away from Bull Mountain Road, which slightly improves
operations at the Roy Rogers Road intersection but results in slight degradation at the Roy Rogers Road & Perth
Road intersection.
It was found that after assuming the Tile Flat Road extension to Mountainside Way was in place and some
drivers use that route instead of remaining on Roy Rogers Road and Scholls Ferry Road, that any new capacity
available in this segment was filled by other regional traffic. In other words, future congestion on parallel
arterials routes (such as OR 99W) could potentially cause drivers to re-route from those roadways to Roy Rogers
Road and Scholls Ferry Road through the River Terrace 2.0 West and South area, which has an influence on the
traffic operational results shown in Table 4. The model assigns vehicles to the shortest travel time routes for
these trips, however drivers may not be that efficient in determining this, at least initially.
D. Travel Time
This performance metric compares the travel time for regional trips on the primary collector streets and along
Roy Rogers Road and Scholls Ferry Road.
Methodology
Average daily motor vehicle volumes were forecasted along roadway segments for 2040 using Washington
County's version of the Metro Regional Transportation Demand Model. These volumes were estimated using the
PM peak hour and include vehicle trips that start and end outside of the River Terrace 2.0 area but travel along
the adjacent arterials (i.e., Roy Rogers Road and Scholls Ferry Road). The total average travel time for regional
trips (i.e., trips that have an origin and destination outside of the River Terrace 2.0 area) between the Scholls
Ferry Road intersection with Tile Flat Road and the Roy Rogers Road intersection with Perth Road was calculated
for each scenario.
The scenarios were ranked based on the following criteria: average travel time for regional trips is forecasted to
be -61 seconds or more from no-build (or half an average cycle length at a signalized intersection), -30 to -60
seconds from no-build, within 30 seconds of no-build, +30 to +60 seconds from no-build, +61 seconds or more
from no-build.
Results
Table 5 shows that the average travel time for regional trips (i.e., trips that have an origin and destination
outside of the River Terrace 2.0 area) between the S Scholls Ferry Road intersection with Tile Flat Road and the
Roy Rogers Road intersection with Perth Road is around 7 minutes in each scenario. The extension of Tile Flat
Road to Mountainside Way (Scenario 2) is not expected to change the average travel time for these regional
trips, while the extension of Mountainside Way to Perth Road (Scenario 3) slightly increases the average travel
time for these regional trips. Although some traffic is shifting from Roy Rogers Road and Scholls Ferry Road to
Tile Flat Road and Mountainside Way under Scenarios 2 and 3, the excess capacity from that shift is largely
negated by other regional traffic shifting to Roy Rogers Road from other nearby congested arterials, therefore
the average travel time along these corridors remains similar under these scenarios.
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However, there is a travel time benefit of roughly 0.3 minutes or 18 seconds for regional trips when both Tile
Flat Road and Mountainside Way are extended (Scenario 4). This represents approximately a 4% reduction in
trip time compared to Scenario 1. Since more trips are shifting to Tile Flat Road and Mountainside Way under
this scenario, the excess capacity is not entirely taken up by other regional traffic, and therefore the average
travel times along Roy Rogers Road and Scholls Ferry Road are slightly reduced when compared to Scenario 1
through the River Terrace 2.0 area.
Ideal Definition Average Travel Time in the
PM Peak Hour (Minutes)*
Change from no-
build (seconds)
Forecasted travel times for
regional trips decrease by more
than one half of a traffic signal
cycle (more than 30 seconds)
once the RT 2.0 Primary and
Secondary Street network is
constructed.
Scenario 1 6.91 -11
Scenario 2 6.88 -13
Scenario 3 7.07 -2
Scenario 4 6.63 -28
The scenarios were ranked with the following compared to the ideal condition:
->=60 secs from
no-build
-30-60 secs from
no-build
+- 30 secs from no-
build
+ 30-60 secs from
no-build
+ >=61 secs from
no-build
TABLE 5 : COMPARISON OF TRAVEL TIME FOR REGIONAL TRIPS
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2. MULTIMODAL NETWORK
The following are performance metrics that compare bicycling, pedestrian, and transit travel between the
primary street network scenarios.
A. Bicycle Level of Traffic Stress (BLTS)
This performance metric compares the types and scale of facilities and crossings needed to maintain low-stress
conditions for bicyclists along the primary collector streets based on expected traffic volumes and speeds.
Methodology
This analysis is based on the ODOT BLTS methodology outlined in the Analysis Procedures Manual Chapter 14 –
Section 14.4 and incorporating best practice principles from the 2024 AASHTO Guide for the Development of
Bicycle Facilities.
• It is assumed that the bicycling network in RT 2.0 will be designed to BLTS 1 (i.e., the highest level of
comfort) to encourage bicyclists of all ages and abilities to use this mode for short- and medium-
distance trips.
• BLTS 1 needs to be maintained on segments, at intersections, and at crossings for the network to
achieve BLTS 1.
• The Tile Flat Road extension and other primary streets are assumed to be collectors with a 2-lane cross-
section and turn lanes at arterial and other key intersections and with a posted speed limit of 25 mph or
less.
• Note that all widths for bike lanes are “useable widths,” which is defined by the 2024 AASHTO Guide for
the Development of Bicycle Facilities as “a smooth, rideable surface clear of surface defects, joints, and
other potential obstructions to minimize crash risk.” The useable width should not include a gutter,
unless the gutter is integrated into the full width of the bicycle facility.
Results & Evaluation
Below are the design requirements to maintain BLTS 1:
• Segment BLTS: cross-sections should include a shared use path or separated bike lanes. If volumes and
speeds are lower, buffered bike lanes may be appropriate. See Appendix A – Table A1 for more detailed
descriptions of required design criteria. All scenarios will be designed similarly and meet BLTS 1 at the
expected speeds and volumes.
• Intersection and crossing BLTS: design treatments to meet BLTS 1 at unsignalized, signalized, and
roundabout intersections as well as at midblock crossings are described in Appendix A – Table A2.
Signalized and roundabout intersections will be designed similarly and meeting BLTS 1 for all scenarios.
The type of unsignalized crossing required depends on traffic volumes. For a 2-lane street at 25 mph or
less, a median crossing is required when traffic volumes exceed 3,000 vpd. Based on these criteria and
the expected ADT (see metric 1B), the following unsignalized crossing infrastructure is needed:
o Scenario 1: median crossings on Mountainside Way north of Jean Louise Drive. No median
required elsewhere. This is a total of 4 median crossings.
o Scenario 2: median crossings on all streets including Tile Flat Road, Mountainside Way, and Bull
Mountain Road. This is a total of 9 median crossings.
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o Scenario 3: median crossings on Mountainside Way north of Bull Mountain Road. No median
required elsewhere. This is a total of 7 median crossings.
o Scenario 4: median crossings on all streets including Tile Flat Road, Mountainside Way, and Bull
Mountain Road. This is a total of 10 median crossings.
Scenario 1 represents the lowest investment needed to achieve BLTS 1. Other scenarios will have some
additional cost and right-of-way dedication associated with the additional median crossing needs. These costs
will have some impact but are not considered significant relative to the overall cost. Right-of-way dedication and
the impact on development yield is considered in metric 4B. Table 6 summarizes the level of infrastructure
needed to achieve BLTS 1 under each scenario.
TABLE 6 : EVALUATION OF INFRASTRUCTURE NEEDED TO MEET BLTS 1
INFRASTRUCTURE NEEDS TO MEET BLTS 1
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Segments Shared use path or
separated bike
lanes meets BLTS
1
Shared use path or
separated bike
lanes meets BLTS
1
Shared use path or
separated bike
lanes meets BLTS
1
Shared use path or
separated bike
lanes meets BLTS
1
Ideal condition-
minimal investment
to create BLTS 1
Intersections BLTS 1 achieved
with median
crossings needed
at 4 locations
BLTS 1 achieved
with median
crossings needed
at all (9) locations
BLTS 1 achieved
with median
crossings needed
at some additional
(7) locations
BLTS 1 achieved
with median
crossings needed
at all (10)
locations
Ideal condition-
minimal investment
to create BLTS 1
Overall Performance
– Relative
Investment Needed
to Meet BLTS 1
Lowest
investment to
achieve BLTS 1
Achieves BLTS 1
with some costs
for median
crossings at all
locations
Achieves BLTS 1
with some costs
for additional
median
crossings
Achieves BLTS 1
with some costs
for median
crossings at all
locations
Ideal condition-
minimal investment
to create BLTS 1
B. Pedestrian Level of Traffic Stress (PLTS)
This performance metric compares the types and scale of facilities and crossings needed to maintain low-stress
conditions for pedestrians along the primary collector streets based on typical crossing spacing standards,
expected traffic volumes, and speeds.
Methodology
This analysis was conducted based on the ODOT PLTS methodology outlined in the Analysis Procedures Manual
Chapter 14 – Section 14.5.
• It is assumed that the pedestrian network in RT 2.0 will be designed to PLTS 1 (i.e., the highest level of
comfort) to support accessibility goals and encourage people to use this mode for short-distance trips.
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• PLTS 1 needs to be maintained on segments, at intersections, and at crossings for the network to
achieve PLTS 1.
• The Tile Flat Road extension and other primary streets are assumed to be collectors with a 2-lane cross-
section and turn lanes at arterial and other key intersections and with a posted speed limit of 25 mph or
less.
Results & Evaluation
Below are the design requirements to maintain PLTS 1:
• Segment PLTS: sidewalk widths should be ≥ 6’ in general and ≥ 8’ in higher traffic and commercial areas.
Sidewalks need to be in good condition with a sufficient width landscape or hardened buffer between it
and the roadway. See Appendix B – Table B1 for more detailed descriptions of required design criteria.
All scenarios will be designed similarly and meet BLTS 1 at the expected speeds and volumes.
• Intersection and crossing PLTS: design treatments to meet PLTS 1 at unsignalized, signalized, and
roundabout intersections as well as at midblock crossings are described in Appendix B – Table B2.
Signalized and roundabout intersections will be designed similarly and meeting BLTS 1 for all scenarios.
The type of unsignalized crossing required depends on traffic volumes. For a 2-lane street at 25 mph or
less, a median crossing is required when traffic volumes exceed 5,000 vpd. Based on these criteria and
the expected ADT (see metric 1B), the following unsignalized crossing infrastructure is needed:
o Scenario 1: no median crossings are required to accommodate pedestrian crossings.
o Scenario 2: median crossings on Mountainside Way south of the Tile Flat Road extension. No
median crossings are required elsewhere to accommodate pedestrian crossings. This is a total of
6 median crossings.
o Scenario 3: median crossings on Mountainside Way north of Sabrina Avenue. No median
crossings are required elsewhere to accommodate pedestrian crossings. This is a total of 2
median crossings.
o Scenario 4: median crossings on Mountainside Way from the Tile Flat Road extension to Bull
Mountain Road. No median crossings are required elsewhere to accommodate pedestrian
crossings. This is a total of 6 median crossings.
Scenario 1 represents the lowest investment needed to achieve PLTS 1. Other scenarios will have some
additional cost and right-of-way dedication associated with the additional median crossing needs. These costs
will have some impact but are not considered significant relative to the overall cost. Right-of-way dedication and
the impact on development yield is considered in metric 4B.
Evaluation of Tile Flat Extension Scenarios
June 2025
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Table 7 summarizes the level of infrastructure needed to achieve PLTS 1 under each scenario.
Evaluation of Tile Flat Extension Scenarios
June 2025
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TABLE 7 : EVALUATION OF INFRASTRUCTURE NEED ED TO MEET PLTS 1
INFRASTRUCTURE NEEDS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Segments Sidewalk with
landscaped buffer
meets PLTS 1
Sidewalk with
landscaped buffer
meets PLTS 1
Sidewalk with
landscaped buffer
meets PLTS 1
Sidewalk with
landscaped buffer
meets PLTS 1 Ideal condition-
minimal investment
to create BLTS 1
Intersections No median
crossings needed
to meet PLTS 1
Median crossing
needed in some
(6) locations to
meet PLTS 1
Median crossings
needed in very few
(2) locations to
meet PLTS 1
Median crossings
needed in some
(6) locations to
meet PLTS 1
Ideal condition-
minimal investment
to create BLTS 1
Overall Performance
– Relative
Investment Needed
to Meet PLTS 1
Lowest
investment to
achieve PLTS 1
Achieves PLTS 1
with some costs
for additional
median crossings
Achieves PLTS 1
with some costs
for additional
median crossings
Achieves PLTS 1
with some costs
for additional
median crossings
Ideal condition-
minimal investment
to create BLTS 1
C. Connectivity
This metric compares the directness and convenience of the multimodal network and identifies any barriers
resulting from the primary street network scenarios related to accessing regional destinations as well as local
destinations including commercial districts, parks, trails, transit stops, etc.
Methodology
The analysis compares performance in three sub-metrics:
• Arterial connections: this compares the number of connections to the arterial street network with a
higher number increasing access for future residents to regional destinations.
• Internal street connectivity: a qualitative review of how well the internal street network supports
development and a comparison of local street permeability measured by intersection density – the
number of intersections per mile of primary street network.
• Walking catchment: this includes a GIS walkshed analysis to compare the percentage of residential
development in RT 2.0 that is within a ½ and 1-mile (i.e., 10- or 20-minute) walk of key destinations
including the two commercial areas in RT 2.0 West and the existing Mountainside High School. Note that
the analysis only includes the primary street network. The local street network may increase the
percentage of development within each walking catchment. However, it is expected that the relative
increase would be the same across scenarios.
Evaluation of Tile Flat Extension Scenarios
June 2025
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Results
Table 8 compares external street network connectivity between scenarios. Table 9 compares internal street
network connectivity.
TABLE 8 : COMPARISON OF EXTERNAL NETWORK CONNECTIVITY
* Includes intersections with the external street network including Scholls Ferry Road, Roy Rogers Road, Perth Road, and
Vandermost Road.
SCENARIO ARTERIAL
CONNECTIONS
EXTERNAL CONNECTIVITY
A 3 Provides connections to Scholls Ferry Road and Roy Rogers Road.
B 4 Extending Tile Flat Road provides a more direct vehicular connection to
regional destinations northwest of RT 2.0.
C 4 Extending Mountainside Way provides an additional connection to RT 1.0
and RT 2.0 South without having to use the arterial network.
D 5 Extending Tile Flat Road provides a more direct vehicular connection to
regional destinations northwest of RT 2.0. Extending Mountainside Way
provides an additional connection to RT 1.0 and RT 2.0 South without having
to use the arterial network.
TABLE 9 : COMPARISON OF INTERNAL NETWORK CONNECTIVITY
SCENARIO CONNECTIVITY INTERSECTIONS* LENGTH
(MILES)
PRIMARY
STREET
INTERSECTION
DENSITY
(INTXNS/MILE)
A Provides internal circulation for RT
2.0. Future development on
Vandermost Road is disconnected
from the rest of RT 2.0.
Development potential is limited
on Vandermost Road.
8 1.05 7.6
B Provides internal circulation for RT
2.0. Future development on
Vandermost Road would be
connected to the rest of RT 2.0.
10 1.69 5.9
C Provides internal circulation for RT
2.0. Future development on
Vandermost Road is disconnected
from the rest of RT 2.0.
Development potential is limited
on Vandermost Road.
10 1.68 6.0
D Provides internal circulation for RT
2.0. Future development on
Vandermost Road would be
connected to the rest of RT 2.0.
12 2.32 5.2
Evaluation of Tile Flat Extension Scenarios
June 2025
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Scenario 1 provides the internal circulation required to support development in RT 2.0 West and includes three
connections to the arterial street network at Scholls Ferry Road & Mountainside Way, Roy Rogers Road & Jean
Louise Drive, and Roy Rogers Road & Bull Mountain Road. Additional street segments are not required to
support development. However, extending Tile Flat Road as part of Scenarios 2 or 4 would provide a fourth
connection to the arterial street network and a more direct vehicular connection to regional destinations
northwest of RT 2.0.
Extending Mountainside Way south to connect to Roy Rogers Road at Perth Road as part of Scenarios 3 or 4
would increase connectivity to RT 1.0 and RT 2.0 South by providing another east-west access route that could
distribute traffic and shorten travel between some destinations in these areas. Scenario 3 would provide four
connections to the arterial street network and Scenario 4 would provide five connections.
Extending Tile Flat Road as part of Scenarios 2 or 4 would provide a connection to any future development on
Vandermost Road, which would otherwise rely on the arterial street network (i.e., Scholls Ferry Road) to connect
to the rest of RT 2.0. Development potential along Vandermost Road is limited and may not justify the cost of
providing an additional connection along the Tile Flat Road alignment solely for the purpose of additional
connectivity.
Table 9 shows that Scenario 1 has the highest intersection density because it has the lowest length of street, but
all scenarios would provide good local connectivity to the developable areas of RT 2.0 West.
The results of the walkshed analysis in Table 10 show that with the extension of Tile Flat Road (Scenario 2),
Mountainside Way (Scenario 3), or both (Scenario 4), there is an incremental increase in the amount of
residential development that can access the Scholls Ferry & Mountainside Way (SFMW) commercial area, the
Mountainside High School, and the Roy Rogers & Bull Mountain (RRBM) commercial area within a ½ mile
walkshed – approximately a 5% to 15% increase. Table 11 shows that these extensions increase the amount of
residential development within a 1-mile walkshed by up to 10% to 30%. Maps of the walkshed analysis are
included in Appendix C.
TABLE 10 : PERCENTAGE OF RESIDENTIAL DEVELOPMENT WITHIN A HALF MILE WALKSHED (10 -
MINUTE WALK)
SCENARIO COMMERCIAL A
(SFMW)
COMMERCIAL B
(RR BM)
MOUNTAINSIDE HIGH
SCHOOL
A 45% 20% 30%
B 55% 20% 35%
C 45% 35% 30%
D 55% 35% 35%
Evaluation of Tile Flat Extension Scenarios
June 2025
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TABLE 11 : PERCENTAGE OF RESIDENTIAL DEVELOPMENT WITHIN A ONE MILE WALKSHED (20 -
MINUTE WALK)
Evaluation
Table 12 compares multimodal connectivity between scenarios. Scenario 1 provides sufficient connectivity for
development with three access points to the arterial road network, good connectivity to River Terrace 1.0 and
South Cooper Mountain, and the highest density of intersections (meaning more opportunities for crossings,
etc.). It does have a lower walkshed coverage for key destinations in the neighborhood than other scenarios.
TABLE 12 : EVALUATION OF MULTIMODAL CONNECTIVITY
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
External Network
Connectivity
(# of arterial connections)
3 4 4 5
Ideal condition – highest
number of connections
Intersection Density
(intersections per mile)
7.6 5.9 6.0 5.2
Ideal condition – highest
density of intersections
Internal Network
Connectivity
Good
connectivity to
RT 1.0/2.0 and
South Cooper
Mountain
Additional
connectivity to
Vandermost
Additional
connectivity to
RT 1.0/2.0
Additional
connectivity to
Vandermost and
RT 1.0/2.0 Ideal condition – highest
number of connections
Walkshed Analysis 60%-70%
coverage
5%-20% more
coverage
5%-15% more
coverage
10%-30% more
coverage
Ideal condition – highest
coverage percentage
Overall Performance for
Connectivity
Provides
sufficient
connectivity for
development
and good
Provides
additional local
and regional
connectivity
Provides
additional local
connectivity
and walkshed
coverage*
Provides the
most local and
regional
connectivity Ideal condition – high
performance in local and
SCENARIO COMMERCIAL A
(SFMW)
COMMERCIAL B
(RR BM)
MOUNTAINSIDE HIGH
SCHOOL
A 70% 60% 65%
B 80% 80% 70%
C 80% 75% 70%
D 85% 90% 75%
Evaluation of Tile Flat Extension Scenarios
June 2025
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SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
regional connectivity and
walkshed coverage
walkshed
coverage
and walkshed
coverage*
and walkshed
coverage*
* Increased traffic volumes and lower intersection densities could increase vehicle speeds and may require traffic calming and additional
midblock pedestrian crossings to meet desirable crossing spacing standards.
Other scenarios were evaluated higher than Scenario 1. Scenario 2 provides an additional connection to the
regional network via the Tile Flat Road extension. This also increases the percentage of development that can
walk to commercial areas and the high school. It also provides a secondary connection for development on
Vandermost Road. However, development potential in that area is limited, and this benefit is not considered
significant.
Scenario 3 provides an additional connection to RT 1.0 and RT 2.0 South and additional walkshed coverage.
Scenario 4 provides both the local and regional connectivity benefits but would have the lowest intersection
density. The increased regional connectivity will increase traffic volumes and lower intersection densities could
increase vehicle speeds and may require traffic calming and additional midblock pedestrian crossings to meet
desirable crossing spacing standards.
D. Vulnerable Road User Safety
This metric compares the traffic exposure and relative safety risk (i.e., number of lanes, crossing distance,
increased conflict with turning movements, etc.) for vulnerable road users including pedestrians and bicyclists
traveling along the primary collector streets and crossing at key intersections including at Roy Rogers Road and
Scholls Ferry Road.
Methodology
Analysis conducted for the City of Tigard’s Transportation Safety Action Plan (TSAP) shows that the High Injury
Network (HIN) is most correlated to ADT, functional class, speed, and demographics (e.g., Oregon social equity
index, percentage of households with no vehicles, etc.).
There is no material difference between scenarios with respect to the functional class, speed, and demographic
factors, i.e., in all scenarios the Tile Flat extension will be a collector street designed at the same speed and
serving the same demographics. However, there will be increased exposure – including for pedestrians and
bicyclists – resulting from differences in traffic volumes and the length of the different scenarios.
• Segment crash exposure is calculated as:
o Sum of (segment ADT * segment miles of road * segment # of lanes)
Different scenarios will also result in different turning movement patterns in the network. This can increase
crash exposure for pedestrians and bicyclists at intersection crossings and affect the cost to mitigate these
impacts.
• Turning movement crash exposure is calculated as follows:
o Sum of turning movements conflicting with pedestrian crossings at an intersection.
o Qualitative analysis of turning movements that conflict with likely school and commercial area
pedestrian routes.
Evaluation of Tile Flat Extension Scenarios
June 2025
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Results & Evaluation
Segment crash exposure is shown in Table 13. Scenario 1 has the lowest internal traffic volumes and therefore
results in the lowest vulnerable road user (VRU) crash exposure. If the total length of all scenarios is considered,
the increase in street network length and traffic volumes results in all other scenarios having higher VRU crash
exposure. Scenario 3 is somewhat (43%) higher than Scenario 1 whereas Scenarios 2 and 4 are significantly
higher (124% and 191%) than Scenario 1.
Segment exposure was evaluated as follows:
• The scenario with the lowest segment exposure was rated as having a medium impact in that it
contributes some level of crash risk.
• Scenarios within a 50% increase of the best performing scenario were considered to have a significant
impact.
• Scenarios with a more than 50% increase from the best performing scenario were considered to have a
very significant impact on crash risk.
TABLE 13 : COMPARISON OF SEGMENT CRASH EXPOSURE
SEGMENT CRASH EXPOSURE
(VEHICLE LANE MILES)
SCENARIO 1 SCENARIO
2 SCENARIO 3 SCENARIO 4
All Segments 7,290 16,350 10,430 21,250
Ideal definition – VRUs crash
exposure is minimized (zero
vehicle-lane-miles)
Lowest overall
VRU crash
exposure
VRU crash
exposure is
considerably
higher than
Scenario 1
(+124%)
VRU crash
exposure is
somewhat
higher than
Scenario 1
(+43%)
VRU crash
exposure is
considerably
higher than
Scenario 1
(+191%)
* This analysis compares exposure on Mountainside Way from Scholls Ferry Road to Bull Mountain Road and on Bull
Mountain Road from Mountainside Way to Roy Rogers Road.
The location of turning movement exposure will change based on the scenario. Turning movement crash
exposure is shown in Table 14. For Scenario 1, major turning movements will occur to and from the arterial
street network at Scholls Ferry Road & Mountainside Way (505 total turning movements during the 2040 PM
peak hour) and at Roy Rogers Road & Bull Mountain Road (860 total turning movements during the 2040 PM
peak hour). These are controlled, signalized locations where these conflicts are expected although the former
will be along a primary walking route to access Mountainside High School. This scenario would see the lowest
turning movement crash exposure internal to the development along the primary walking and bicycling routes
on Mountainside Way and Bull Mountain Road. This scenario would see 80 total turning movements during the
2040 PM peak hour at the Tile Flat Road Extension & Mountainside Way intersection.
Evaluation of Tile Flat Extension Scenarios
June 2025
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Scenario 3 would increase turning movement crash exposure when compared to Scenario 1 at the Scholls Ferry
Road & Mountainside Way intersection (i.e., 530 total turning movements during the 2040 PM peak hour) but
would reduce turning movements at the Roy Rogers Road & Bull Mountain Road intersection (i.e., 755 total
turning movements during the 2040 PM peak hour) and shift them further south to the Roy Rogers Road & Perth
Road intersection where there may be fewer pedestrian crossings expected. Turning movement exposure
internal to the development would increase somewhat under this scenario (i.e., +20 total turning movements
during the 2040 PM peak hour at the Tile Flat Road Extension & Mountainside Way intersection).
Scenarios 2 and 4 would reduce turning movements when compared to Scenario 1 at the Scholls Ferry Road &
Mountainside Way intersection (i.e., -50 total turning movements during the 2040 PM peak hour) and increase
turning movements when compared to Scenario 1 at the Roy Rogers & Bull Mountain Road intersection (i.e.,
+240 and +110 total turning movements during the 2040 PM peak hour respectively). These scenarios would
also increase turning movement exposure internal to the RT 2.0 WEST development (i.e., +225 total turning
movements during the 2040 PM peak hour at the Tile Flat Road Extension & Mountainside Way intersection),
along what will likely be a primary walking route to access Mountainside High School and the Scholls Ferry &
Mountainside Way commercial area. Larger or more intense intersection designs – such as a protected
intersections, roundabouts, or signals – may be required to address left- and right-turning conflicts with active
transportation users at this intersection.
TABLE 14 : COMPARISON OF TURNING MOVEMENT CRASH EXPOSURE
INTERSECTION TOTAL TURNING MOVEMENT CONFLICTS WITH
PEDESTRIAN CROSSINGS
(PM PEAK VEHICLES PER HOUR)
SCENARIO
1
SCENARIO
2
SCENARIO
3
SCENARIO
4
Scholls Ferry Road / Mountainside Way 505
(+11%)
455
(lowest)
530
(+16%)
455
(lowest)
Tile Flat Road / Mountainside Way
80
(lowest)
170
(+112%)
100
(+25%)
190
(+138%)
Roy Rogers Road / Bull Mountain Road 860
(+14%)
1,100
(+46%)
755
(lowest)
970
(+28%)
Roy Rogers Road / Perth Road
- - 225
(lowest)
255
(+13%)
Total Turning Movement Conflicts 1,445 vph 1,725 vph 1,610 vph 1,870 vph
Ideal definition – VRUs crash
exposure is minimized (zero vph
turning movement conflicts)
Lowest
overall VRU
crash
exposure
VRU crash
exposure
somewhat
higher than
Scenario 1
(+19%)
VRU crash
exposure
somewhat
higher than
Scenario 1
(+11%)
VRU crash
exposure
considerably
higher than
Scenario 1
(+29%)
Evaluation of Tile Flat Extension Scenarios
June 2025
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Turning movement exposure was evaluated as follows:
• The scenario with the lowest exposure was rated as having a medium impact in that it contributes some
level of crash risk.
• Scenarios within a 25% increase of the best performing scenario were considered to have a significant
impact.
• Scenarios with a more than 25% increase from the best performing scenario were considered to have a
very significant impact on crash risk.
Table 15 summarizes the evaluation of vulnerable road user safety. Scenario 1 represents the lowest vulnerable
road user crash exposure both in terms of segment and turning movement exposure. Scenarios 2 and 4
represent somewhat higher exposures from increased traffic movements on the internal street network.
Scenario 4 considerably increases crash exposure because it has the highest internal street traffic volumes and
changed turning movement patterns conflicting with pedestrian crossing routes.
TABLE 15 : EVALUATION OF VULNERABLE ROAD USER SAFETY
SCENARIO
1 SCENARIO 2 SCENARIO
3 SCENARIO 4
Segment Crash Exposure 7,290 16,350 10,430 21,250
Ideal definition – VRUs crash
exposure is minimized (zero
vehicle-lane-miles)
Lowest
overall VRU
crash
exposure
VRU crash
exposure is
considerably
higher than
Scenario 1
(+124%)
VRU crash
exposure is
somewhat
higher than
Scenario 1
(+43%)
VRU crash
exposure is
considerably
higher than
Scenario 1
(+191%)
Total Turning Movement Conflicts 1,445 vph 1,725 vph 1,610 vph 1,870 vph
Ideal definition – VRUs crash
exposure is minimized (zero
vph turning movement
conflicts)
Lowest
overall VRU
crash
exposure
VRU crash
exposure
somewhat higher
than Scenario 1
(+19%)
VRU crash
exposure
somewhat
higher than
Scenario 1
(+11%)
VRU crash
exposure
considerably
higher than
Scenario 1
(+29%)
Overall Performance for VRU Safety Lowest
VRU crash
exposure
VRU crash
exposure
higher than
Scenario 1
VRU crash
exposure
somewhat
higher than
Scenario 1
VRU crash
exposure
considerably
higher than
Scenario 1
Ideal definition – VRUs crash exposure
is minimized (zero)
Evaluation of Tile Flat Extension Scenarios
June 2025
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E. Future Transit Service
This metric compares the connectivity, travel time, and coverage performance for potential future transit
service along the primary street network.
Methodology
The project team understands that TriMet will be extending service to Mountainside High School by 2028 as part
of its Forward Together service expansion plan. TriMet would need to show >10 predicted boarding rides per
hour to consider future service in the new development areas. Areas of River Terrace 1.0 and 2.0, South Cooper
Mountain, and Kingston Terrace may all at some point meet this metric. There are numerous ways to service
these areas with transit including regional services reaching into all or parts of these areas or local services to
circulate and collect passengers for transfer at a regional transit hub. Street design standards will consider
transit vehicle needs to make sure that the primary street network can accommodate future transit service.
The Tile Flat Extension scenarios were evaluated to assess whether any of the scenarios created barriers or
additional opportunities for future transit service compared to other scenarios. This included considering the
amount of flexibility each scenario provides for route planning and circulation, potential destinations along the
service route, and the potential to create regional transit hubs.
Results & Evaluation
Table 16 shows that Scenarios 2, 3, and 4 provide additional route flexibility but the additional connections
beyond Scenario 1 are likely redundant for transit as the most effective route through RT2.0 would be via
Mountainside Way and Bull Mountain Road. This route covers a significant portion of development, provides
better connections to adjacent neighborhoods, would serve the two proposed commercial districts in RT2.0, and
could help create transit and mobility hubs at mixed-use commercial nodes. Increases in traffic on the internal
street network (see Metric 1B) could increase transit travel times under Scenarios 2, 3, and 4.
Evaluation of Tile Flat Extension Scenarios
June 2025
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Table 17 summarizes the evaluation of future transit service for RT 2.0. The primary transit route along
Mountainside Way and Bull Mountain Road provides good coverage to the RT 2.0 development. This route is the
most likely to be used under all scenarios to ensure good access to commercial hubs. Scenario 1 does not
provide any route flexibility but would minimize transit delays as the lowest traffic volume scenario. Scenario 2
provides a route option on Tile Flat Road although that route is unlikely given residential densities along this
corridor compared to others (e.g., Mountainside Way through South Cooper Mountain). Scenarios 3 and 4 do
provide additional route options via the Mountainside Way extension to Perth Road that could provide
secondary service to RT 1.0 and RT 2.0 South. Scenarios 2, 3, and 4 see increased traffic volumes on the primary
street network that could result in transit delays.
TABLE 16 : COMPARISON OF FUTURE TRANSIT SERVICE
SCENARIO TRANSIT CONSIDERATIONS
A • This scenario would allow for an efficient extension of existing service along
Scholls Ferry Road to circulate through RT 2.0 West via Mountainside Way and
into RT 1.0 via Bull Mountain Road before returning to Scholls Ferry Road to
connect to the Washington Square Transit Center.
• It could also support local or microtransit service connecting RT 1.0 and 2.0,
Kingston Terrace, and South Cooper Mountain.
• The commercial node at Scholls Ferry Road & Mountainside Way could serve as a
regional transit hub and mobility hub.
B • This scenario may offer an additional route option for any services using Tile Flat
Road though it is likely service would run through South Cooper Mountain and
down Mountainside Way making this additional connection redundant for transit.
• Routing transit along the extension of Tile Flat Road would deviate the route from
the commercial district at Scholls Ferry Road & Mountainside Way.
C • This scenario may offer an additional route option to serve RT 1.0, RT 2.0 South,
and Kingston Terrace using the Mountainside Way extension to Perth Road
(without having to use the arterial street network). Base service is likely to run
along Mountainside Way and Bull Mountain Road through RT 2.0 West.
• Routing transit along the extension of Mountainside Way would deviate the route
from the commercial district at Roy Rogers Road & Bull Mountain Road.
D • This scenario may offer an additional route option to serve RT 1.0, RT 2.0 South,
and Kingston Terrace using the Mountainside Way extension to Perth Road
(without having to use the arterial street network). Base service is likely to run
along Mountainside Way and Bull Mountain Road through RT 2.0 West.
• Routing transit along the extension of Mountainside Way would deviate the route
from the commercial district at Roy Rogers Road & Bull Mountain Road.
• This scenario may offer an additional route option using the Tile Flat Road
extension though it is likely service would run through South Cooper Mountain and
down Mountainside Way making this additional connection redundant for transit.
• Routing transit along the extension of Tile Flat Road would deviate the route from
the commercial district at Scholls Ferry Road & Mountainside Way.
Evaluation of Tile Flat Extension Scenarios
June 2025
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TABLE 17 : EVALUATION OF FUTURE TRANSIT SERVICE
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Provides a Primary Service Route
Through RT2.0
Yes Yes Yes Yes
Ideal definition – provides
a primary route option
with good residential and
commercial access
Additional Route Options Primary route
option only
Additional
route option
with Tile Flat
extension but
does not serve
significant
development
Additional route
options with
extension of
Mountainside
Way to serve RT
1.0 and 2.0
South
Additional route
options with
extension of
Mountainside
Way to serve RT
1.0 and 2.0
South
Ideal definition –
options for alternative
routes that provide
additional coverage
Commercial Areas Impacted by
Alternative Routes
Transit passes
by both
commercial
areas
Alternative
routes would
not pass by the
SFMW
commercial
area
Alternative
routes would not
pass by the
RRBM
commercial area
Alternative
routes would
not pass by the
SFMW or RRBM
commercial
areas
Ideal definition – transit
passes by both
commercial areas
Potential for Transit Delay due to
Traffic
Lowest traffic
volumes will
result in
lowest transit
delays
Higher traffic
volumes on
Mountainside
Way will
increase transit
delay
compared to
Scenario 1
Slightly higher
traffic volumes
on Mountainside
Way but similar
to Scenario 1
Highest traffic
volumes on
Mountainside
Way will
increase transit
delay compared
to Scenario 1
Ideal definition – no delay
to transit from traffic
Overall Performance for Future
Transit
Primary
route
provides
good
coverage and
lowest traffic
volumes
minimize
delays
Alternative
routes
available but
may reduce
coverage.
Traffic
volumes may
result in
some transit
delays
Alternative
routes could
provide
additional
residential
coverage but
reduce
commercial
exposure.
Alternative
routes could
reduce
commercial
exposure.
Traffic
volumes may
result in
transit delays
Ideal definition – high performance
in base coverage, route options,
and minimal transit delay
Evaluation of Tile Flat Extension Scenarios
June 2025
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3. ENVIRONMENTAL / LIVABILITY
The following provides performance metrics that are proposed to compare environmental and livability
characteristics between the primary street network scenarios.
A. GHG and Emissions
This metric compares the relative scale and location of occurrence of GHG and emissions along the primary
collector streets.
Methodology
The amount of transportation-related greenhouse gas and other emissions produced by vehicle operations
depends on:
• The mix of vehicle types and their emitting characteristics. For example, the percentage of internal
combustion engines, diesel engines, heavy vehicles, hybrid vehicles, and all electric vehicles.
• Vehicle miles traveled: the number of miles traveled by each vehicle type.
Where these emissions occur is also important in terms of whether there are disproportionate impacts to
residents, school children, or other vulnerable populations.
GHG and other emissions will generally follow VMT patterns (see Metric 1A) with some variation depending on
the fleet mix of different traffic components. It is unknown whether the vehicle fleet mix of residents moving to
RT 2.0 will be significantly different to the fleet mix of the surrounding street network. This may be influenced by
development standards for RT 2.0 that could encourage the adoption of electric vehicles for those residents that
will own vehicles. For example, development standards may require or incentivize on-site charging options for
residences with garages and/or electric vehicle (EV) charging in multifamily parking facilities and publicly
available parking lots. These requirements could result in traffic to and from the development producing fewer
per mile emissions than external traffic that might cut through the neighborhood.
In that case, impacts would follow similar patterns to Metric 1A1 – VMT on the primary and secondary street
network with Scenario 1 having the lowest potential for emissions internal to the RT 2.0 West because it
includes primarily trips related to the RT 2.0 West development and has the fewest regional trips passing
through the neighborhood. VMT was calculated for the component of regional traffic expected to cut-through
the neighborhood as part of Metric 1A1 and is included in Table 18.
Results & Evaluation
Scenarios 2, 3, and 4 will attract higher volumes of regional “cut-through” trips compared to Scenario 1 and will
result in higher VMT (see Table 18). This could result in higher emissions internal to the RT 2.0 West
development and increased exposure for local residents, school aged children walking to school, at parks and
community gathering spaces, and near environmentally sensitive locations such as streams and wetlands.
Evaluation of Tile Flat Extension Scenarios
June 2025
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TABLE 18 : EVALUATION OF GHG AND EMISSIONS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Cut-through VMT (2040) 300 VMT per day 4,490 VMT per
day
1,600 VMT per
day
4,650 VMT per
day
Ideal definition – cut-through
VMT is minimized (zero)
Lowest potential
for emissions in
RT 2.0
Emissions
potential is
considerably
higher than
Scenario 1
(+1,396%)
Emissions
potential is
somewhat higher
than Scenario 1
(+433%)
Emissions
potential is
considerably
higher than
Scenario 1
(+1,450%)
* A cut-through trip is defined as one that starts and ends outside of the River Terrace 2.0 area, but travels along Tile Flat Road, Mountainside Way, or
Sabrina Avenue and through the River Terrace 2.0 area. The total for all scenarios is based on the segment of Mountainside Way, south of the Tile Flat
Road intersection.
B. Natural Resource Impacts
This metric compares the number of stream crossings and impacts to specimen trees and groves, wetlands, and
impervious surface under each of the primary street network scenarios.
Methodology
The analysis compares scenarios for the following performance measures:
• Stream crossings:
o A comparison of the number of stream crossings required for each scenario. The primary street
network for RT 2.0 West shown on Figure 5 was designed to minimize the number and extent of
stream crossings. Crossing alignment and location could shift to further minimize impacts and
costs but the assumptions in Figure 5 are sufficient for an order of magnitude comparison of
potential impacts.
o Scenarios were rated based on the number of crossings required. Given the significance of
stream crossings, scenarios needing additional crossings were rated as having higher impacts to
natural resources.
• Specimen trees and groves:
o A comparison of the potential impact of the primary street network scenarios on specimen trees
and groves. The primary street network for RT 2.0 West shown on Figure 5 was designed to as
much as possible avoid impacts on specimen trees and groves.
o Scenarios were rated based on the number of specimen trees or groves they impacted.
• Impervious surface:
o Area of impervious surface = Sum (feet of impervious surface per cross-section segment x length
of street segment). This is calculated for two different primary street cross-section options in
Table D1 in Appendix D.
o Scenarios were evaluated as follows:
▪ The scenario with the lowest impervious surface area was rated as the best scenario.
▪ Scenarios within 25% of the best performing scenario were considered to have similar
impacts.
Evaluation of Tile Flat Extension Scenarios
June 2025
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▪ Scenarios were considered to have a medium impact if their impervious surface area
was 25% to 75% higher than the best performing scenario.
▪ Scenarios were considered to have a high impact if their impervious surface area was
more than 75% higher than the best performing scenario.
• Impacts to wetlands and areas with environmental designations:
o The primary street network for RT 2.0 WEST shown on Figure 5 was designed to minimize
impacts to wetlands identified as significant by the project team. Scenarios were evaluated
based on a qualitative assessment of their potential impact.
Results
Table 19 shows that the least impact on natural resources would come from Scenario 1. The shorter length of
this scenario results in less impervious surface and fewer (two) stream crossings. All scenarios are likely to have
some impact to the tree grove located in the southeast corner of the Scholls Ferry Road & Mountainside Way
intersection.
Scenarios 2 and 3 have increased natural resource impacts related to an additional stream crossing and
increased impervious surface (approximately 60% more impervious surface than Scenario 1). Scenario 4 has an
even more significant impact with a fourth stream crossing and the most impervious surface (approximately
120% more impervious surface than Scenario 1). Infrastructure costs will be significantly more under these
scenarios to construct additional stream crossings and treat runoff from increased impervious surface.
All scenarios are likely to have some impact to the tree grove located in the southeast corner of the Scholls Ferry
Road & Mountainside Way intersection. Scenarios 1 and 3 could have some additional impacts on this tree grove
depending on the size of the required design to accommodate higher turning movements at this intersection.
The crossing of the north-south creek parallel to Vandermost Road is near an existing known beaver dam (see
Figure 10). While the habitat quality and value of this area is unknown, it is possible that a Tile Flat Road crossing
at this location could impact riparian habitat, wetlands, and hydrology modified by the beaver dam. Visits to the
site showed significant pond-like features around the creek bed, further south than the wetlands previously
mapped in the concept plan. Depending on detailed wetland delineation during design, a street crossing at this
location (included as part of Scenarios 2 and 4) could trigger time and cost-intensive state and federal permitting
impacts. Additionally, the steep slopes in this area and the potential need to set back footings from the wetland
could increase structural cost of a bridge at this location.
Evaluation of Tile Flat Extension Scenarios
June 2025
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FIGURE 10 : LOCATION AND PHOTOGRAPH OF EXISTING KNOWN BEAVER DAM.
Evaluation
Natural resource impacts were evaluated based on the results above and summarized in Table 19. Scenario 1
has the least impact on natural resources. Scenarios 2 and 4 have some impacts given the need for additional
stream crossings, increased impervious surface, and potential wetlands impacts from the Tile Flat Road
extension under Scenario 2. Scenario 4 was considered to have a significant impact to natural resources given
the need for two additional stream crossings, a more than doubling of impervious surface, and potential
wetlands impacts from the Tile Flat Road extension.
TABLE 19 : EVALUATION OF NATURAL RESOURCE IMPACTS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Stream Crossings 2 3 3 4
Ideal condition – no stream
crossings
Fewest stream
crossings
One additional
stream crossing
compared to
Scenario 1
One additional
stream crossing
compared to
Scenario 1
Two additional
stream crossings
compared to
Scenario 1
Specimen Trees and Groves 1* 1 1* 1
Ideal condition – no impact
to specimen trees and
groves
Potentially
greater impact to
tree grove at
Scholls Ferry &
Mountainside
Way depending
on intxn design
Potential impact
to tree grove at
Scholls Ferry &
Mountainside
Way
Potentially
greater impact to
tree grove at
Scholls Ferry &
Mountainside
Way depending
on intxn design
Potential impact
to tree grove at
Scholls Ferry &
Mountainside
Way
Impervious Surface 332,600 sq.ft. 535,400 sq.ft.
(+61%)
532,200 sq.ft.
(+60%)
735,000 sq.ft.
(+121%)
Evaluation of Tile Flat Extension Scenarios
June 2025
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SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Ideal condition –
impervious surface limited
to primary development
needs
Lowest
impervious
surface to meet
development
needs
Increase in
impervious
surface to extend
Tile Flat Road
Increase in
impervious
surface to extend
Mountainside
Way
Significant
increase in
impervious
surface to extend
Tile Flat Road
Wetland Impacts No expected
impact
Potential impact
depending on
wetland
designation near
Vandermost
No expected
impact
Potential impact
depending on
wetland
designation near
Vandermost
Ideal condition – no
impacts to wetlands
Overall Performance for
Natural Resource Impacts
Fewest stream
crossings, some
impact to trees,
lowest
impervious
surface
Additional
stream
crossing, some
impact to trees,
potential
wetlands
impact,
increased
impervious
surface
Additional
stream
crossing, some
impact to trees,
increased
impervious
surface
Two additional
stream
crossings, some
impact to trees,
potential
wetlands
impact, highest
impervious
surface
Ideal condition – minimal
impact to streams, trees,
wetlands, and impervious
surface
^ Based on pavement surface from unidirectional bike lanes option in Table D1 in Appendix D.
* Potential for additional impact if an increased intersection footprint is required at Scholls Ferry Road & Mountainside Way.
C. Livability Impacts of Regional Vehicle Trips
This metric considers the type of trips (e.g., local versus regional) along the primary collector streets and
compares the number of trips going through the River Terrace 2.0 development that are attributable to regional
(cut-through) trips.
Methodology
The forecasted local and regional motor vehicle traffic volumes were estimated along roadway segments for
2040 using Washington County's version of the Metro Regional Transportation Demand Model. The volumes
were based on the PM peak hour and factored up by 10 to represent 2040 ADT. The volumes include the vehicle
trips that start and end outside of the River Terrace 2.0 area but travel along the primary collector street
network in the River Terrace 2.0 West subarea (i.e., Tile Flat Road, Mountainside Road, or Sabrina Avenue).
Results & Evaluation
Table 20 shows the volume of expected cut-through traffic on Mountainside Way and the relative increase
compared to the best performing scenario. Scenarios were evaluated as follows:
• Scenario 1 has some cut-through traffic, but a relatively minor amount compared to typical collector
volume ranges and was scored as having a small impact.
• Given cut-through volumes for the best performing scenario (Scenario 1) are low, scenarios were
considered to have a medium impact if their cut-through traffic was 2- to 5-times that of the best
performing scenario. Scenario 3 will see an increase in cut-through traffic from the extension of
Mountainside Way to Perth Road.
Evaluation of Tile Flat Extension Scenarios
June 2025
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• Scenarios were considered to have a significant impact if their cut-through traffic was 5- to 10-times that
of the best performing scenario. Scenarios were considered to have a very significant impact if their cut-
through traffic was more than 10-times that of the best performing scenario. Scenario 2 will see a
considerable increase in cut-through traffic from extending Tile Flat Road. Scenario 4 will see an even
higher increase from extending both Tile Flat Road and Mountainside Way.
TABLE 20 : TYPE OF TRAVEL ON THE PRIMARY STREET NETWORK
CUT -THROUGH VEHICLE TRIPS (2040 ADT)*
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Mountainside Way, south of
Tile Flat Road Extension 200 vpd 2,300 vpd
(+1050%)
800 vpd
(+300%)
3,300 vpd
(+1550%)
Ideal definition – cut-
through traffic is minimized
(zero vpd)
Lowest cut-
through traffic
and a small
proportion of
street volume
Cut-through
traffic is
considerably
higher than
Scenario 1 and
high proportion
of street volume
Some increase in
cut-through
traffic compared
to Scenario 1
and relatively
small portion of
street volume
Cut-through
traffic is
considerably
higher than
Scenario 1 and
high proportion
of street volume
* A cut-through trip is defined as one that starts and ends outside of the River Terrace 2.0 area, but travels along Tile Flat Road, Mountainside Way, or
Sabrina Avenue and through the River Terrace 2.0 area. The total for all scenarios is based on the segment of Mountainside Way, south of the Tile Flat
Road intersection.
Evaluation of Tile Flat Extension Scenarios
June 2025
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4. DEVELOPMENT FEASIBILITY
The following section provides performance metrics that compare potential impacts on the development
feasibility of River Terrace 2.0 between the primary street network scenarios.
A. Support to Commercial Areas
This metric compares how well the primary street network scenarios align travel by multiple modes to connect
with the planned commercial areas shown on Figure 11.
FIGURE 11 : PLANNED COMMERCIAL AREAS IN RIVER TERRACE 2.0 WEST RELATIVE TO KEY
STREET SEGMENTS.
SW Lasich Ln
SW Bull
Mtn Rd
SW Beef Bend Rd
SW
R
o
y
R
o
g
e
r
s
R
d
SW Scholls Ferry Rd
SW Jean Louise Rd
SW
Woodhue St
SW
R
i
v
e
r
T
e
r
r
a
c
e
B
l
v
d
SW
M
o
u
n
t
a
i
n
s
i
d
e
W
ay
SW
V
a
n
d
e
r
m
o
s
t
Rd
SW Tile Flat Rd SW
Clementine St
A
A
B
B
C
Scholls Ferry Road
& Mountainside
Way (SFMW)
Roy Rogers Road &
Bull Mountain
Road (RRBM)
Evaluation of Tile Flat Extension Scenarios
June 2025
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Methodology
The analysis considers two performance measures for each of the commercial areas:
• The ADT passing the two commercial areas in RT 2.0 West (shown on Figure 6 through Figure 9) both on
the arterial street network and the collector street network.
• Walkshed analysis:
o GIS analysis to calculate the percentage of residential development in RT 2.0 West that is within
a ½-mile and 1-mile walk of the two commercial areas (i.e., a 10- and 20-minute walk). Note that
the analysis only includes the primary street network. The local street network may increase the
percentage of development within each walking catchment. However, it is expected that the
relative increase would be the same across scenarios.
The results of these analyses are summarized in Table 21.
Results & Evaluation
An analysis by Johnson Economics found that the Scholls Ferry & Mountainside Way (SFMW) commercial area is
more likely to support major commerce, while the Roy Rogers & Bull Mountain (RRBM) commercial area is more
appropriate for smaller scale walkable mixed-use development. This means that the SFMW area is more
dependent on vehicle access and traffic exposure to succeed. Since the RRBM commercial area is intended as a
smaller commercial node primarily serving the adjacent development, walk/bike access may be more important
to its success. These priorities have been considered in the evaluation.
Table 21 shows that for the SFMW commercial area, Scenario 3 provides the most traffic exposure closely
followed by Scenario 1 (2% less than Scenario 3). Scenarios 2 and 4, because of the traffic drawn to the Tile Flat
Road extension, see 17% and 20% less pass-by traffic at this commercial area compared to Scenario 3.
The results of the walkshed analysis included in Table 11 (see metric 2C) show that with the extension of Tile Flat
Road (Scenario 2), Mountainside Way (Scenario 3), or both (Scenario 4), there is an incremental increase in the
amount of residential development that can access the SFMW commercial areas within a 1-mile walkshed of the
SFMW commercial area – up to a 15% increase. It’s important to note that walkshed modeling is an inexact
science at this scale and for transportation networks that do not yet exist, and so it’s likely that any differences
between the scenarios are marginal at best.
Therefore, while the impacts are somewhat off-setting between the accessibility and visibility by different
modes, Scenario 3 best balances multimodal accessibility with focusing vehicle traffic through the planned
SFWM commercial area.
For the RRBM commercial area, Scenario 2 provides the most traffic exposure because of the additional traffic
drawn to the Tile Flat Road extension that is then routed along Bull Mountain Road past this commercial area.
Scenario 1 (which does not have the extension of Tile Flat Road) sees approximately 7% less pass-by traffic
compared to Scenario 2. Scenarios 3 and 4 that extend Mountainside Way to Perth Road see 14% and 10% less
pass-by traffic compared to Scenario 2.
Evaluation of Tile Flat Extension Scenarios
June 2025
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TABLE 21 : EVALUATION OF SUPPORT TO COMMERCIAL AREAS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
SCHOLLS FERRY ROAD & MOUNTAINSIDE WAY COMMERCIAL AREA
Pass-by traffic (ADT) 28,600 vpd
(-2%)
24,300 vpd
(-17%)
29,300 vpd
(highest)
23,400 vpd
(-20%)
Ideal definition –
maximize traffic
passing by commercial
areas
Slightly less but
negligible
difference in
pass-by traffic
compared to
Scenario 3
Significantly less pass-
by traffic compared to
Scenario 3
Highest pass-by
traffic
Significantly less
pass-by traffic
compared to
Scenario 3
Walkshed Analysis 70% 80% 80% 85%
Ideal condition –
highest coverage
percentage
15% less
coverage
compared to
Scenario 4
5% less coverage
compared to Scenario
4
5% less
coverage
compared to
Scenario 4
Highest coverage
Overall Performance High pass-by
traffic but lower
walkshed
coverage
Significantly less pass-
by traffic and good
walkshed coverage
Highest pass-by
traffic and good
walkshed
coverage
Significantly less
pass-by traffic and
additional walkshed
coverage
Ideal condition –
maximize pass-by traffic
with good walkability
ROY ROGERS ROAD & BULL MOUNTAIN ROAD COMMERCIAL AREA
Pass-by traffic (ADT) 38,900 vpd
(-7%)
42,000 vpd
(highest)
36,300 vpd
(-14%)
37,700 vpd
(-10%)
Ideal definition –
maximize traffic
passing by commercial
areas
Somewhat less
pass-by traffic
compared to
Scenario 2
Highest pass-by traffic Significantly less
pass-by traffic
compared to
Scenario 2
Significantly less
pass-by traffic
compared to
Scenario 2
Walkshed Analysis 60% 80% 75% 90%
Ideal condition –
highest coverage
percentage
30% less
coverage
compared to
Scenario 4
10% less coverage
compared to Scenario
4
15% less
coverage
compared to
Scenario 4
Highest coverage
Overall Performance High pass-by
traffic but lower
walkshed
coverage
Highest pass-by traffic
and good walkshed
coverage
Significantly less
pass-by traffic
and reduced
walkshed
coverage
Somewhat less
pass-by traffic but
highest walkshed
coverage
Ideal condition –
maximize pass-by traffic
with good walkability
COMBINED IMPACT TO COMMERCIAL AREAS
Ideal definition –
maximize traffic
passing by and
walkshed coverage for
commercial areas
Provides highest
overall pass-by
traffic but lower
walkshed
coverage
Provides highest pass-
by traffic for RRBM
and good walkshed
coverage
Provides best
performance for
SFMW but lower
pass-by traffic
for RRBM
Provides best
performance for
RRBM but lower
pass-by traffic for
SFMW
Evaluation of Tile Flat Extension Scenarios
June 2025
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The results of the walkshed analysis included in Table 11 (see metric 2C) show that with the extension of Tile Flat
Road (Scenario 2), Mountainside Way (Scenario 3), or both (Scenario 4), there is an incremental increase in the
amount of residential development that can access the RRBM commercial areas within a 1-mile walkshed of the
RRBM commercial area – up to a 30% increase.
Therefore, while the impacts are somewhat off-setting between the accessibility and visibility by different
modes, Scenario 4 best balances multimodal accessibility increasing the walkshed coverage for the planned
RRBM commercial area.
It is noted that overall, Scenario 1 has the highest overall pass-by traffic exposure for the two commercial areas
combined, but the lowest walkshed coverage. Scenario 4 has the lowest combined pass-by traffic exposure but
the highest walkshed coverage. Scenarios 2 and 4 fall somewhere in between on both metrics.
Regardless of the scenario, the active transportation network should be planned to access and support the
commercial areas. A high level of design is needed to separate pedestrians, bicyclists, and motor vehicles and to
create inviting pedestrian spaces and opportunities for outside activities, seating, and sidewalk cafes.
Regardless of the scenario, the most likely future transit route through the neighborhood will be along
Mountainside Way and Bull Mountain Road. This will maximize transit access to these commercial areas and
increase their role as mobility hubs for the neighborhood.
B. Land Use and Development Feasibility
This metric compares the potential impacts to developable acreage, development intensity, or development
form resulting from the different primary street network scenarios.
Methodology
The analysis includes a quantitative assessment of the potential development impacts between scenarios
focusing on development yield, development form, cost, and feasibility.
Results
Evaluation of Tile Flat Extension Scenarios
June 2025
Page | 45
Table 22 summarizes the potential impacts on development from the different primary street network
scenarios. The primary street network identified in Scenario 1 is what is required for development to occur. It
has the fewest stream crossings and the lowest traffic volumes meaning that the required design of roadways
and intersections will minimize cost and development form impacts.
Evaluation of Tile Flat Extension Scenarios
June 2025
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TABLE 22 : POTENTIAL IMPACTS ON LAND USE AND DEVELOPMENT FEASIBILITY
SCENARIO DEVELOPMENT POTENTIAL
A • This is the basic primary street network needed for development.
• The area on Vandermost Road would be disconnected from the rest of the network
which may further limit its development potential.
• This scenario has the fewest stream crossings and the lowest traffic volumes reducing
the size of internal streets and intersections. This scenario minimizes impacts on
development cost and form.
B • Extending Tile Flat Road is not essential to developing RT 2.0 but would better connect
development on Vandermost Road to the rest of RT 2.0 West.
• Extending Tile Flat Road will require additional dedication for right-of-way and
intersection design and may require dedication for additional property setbacks to
account for increases in traffic volume. This could have a minor impact on potential
development yield.
• Development on Vandermost Road is expected to be low intensity and would not
(alone) justify the cost to extend Tile Flat Road and construct an additional stream
crossing.
• Right-of-way will need to be reserved for the Tile Flat Road extension until it is
constructed. Its form will need to be determined for interim phases of development.
C • The area on Vandermost Road would be disconnected from the rest of the network
which may limit its development potential.
• Extending Mountainside Way is not essential to developing RT 2.0 and part of the
extension is outside the urban growth boundary and is not currently developable.
• Extending Mountainside Way and constructing an additional stream crossing will add
significant cost to the development for little or no additional development yield.
• Extending Mountainside Way will require additional dedication for right-of-way and
intersection design and may require dedication for additional property setbacks to
account for increases in traffic volume. This could have a minor impact on cost and
potential development yield.
• Right-of-way will need to be reserved for the Mountainside Way extension until it is
constructed. Its form will need to be determined for interim phases of development.
D • Extending Tile Flat Road is not essential to developing RT 2.0 but would better connect
development on Vandermost Road to the rest of RT 2.0 West.
• Development on Vandermost Road is expected to be low intensity and would not
(alone) justify the cost to extend Tile Flat Road and construct an additional stream
crossing.
• Extending Mountainside Way is not essential to developing RT 2.0 and part of the
extension is outside the urban growth boundary and is not currently developable.
• Extending Tile Flat Road and Mountainside Way and constructing two additional stream
crossings will add significant cost to the development for little or no additional
development yield.
• Extending Tile Flat Road and Mountainside Way will require additional dedication for
right-of-way and intersection design and may require dedication for additional property
setbacks to account for increases in traffic volume. This could have a moderate impact
on potential development yield.
• Right-of-way will need to be reserved for the Tile Flat Road and Mountainside Way
extensions until they are constructed. Their form will need to be determined for interim
phases of development.
Evaluation of Tile Flat Extension Scenarios
June 2025
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The area of RT 2.0 along Vandermost Road is constrained by existing natural resources and is only expected to
support lower intensity residential and smaller development parcels. The land use approach proposed in the
Housing Plan designates this land for the lowest density development, but the final zoning map and regulations
could lower this density even further in response to the environmental constraints and to address volume
concerns at the intersection of Scholls Ferry Road & Vandermost Road. Without an extension of Tile Flat Road,
this area would depend on the use of the arterial street network to connect to the rest of RT 2.0 which may
further limit its development potential and sense of connection to the rest of RT 2.0.
The Tile Flat Road and Mountainside Way extensions are not required to make the RT 2.0 development feasible.
The additional creek crossings needed for Scenarios 2, 3, and 4 in the portion within the River Terrace 2.0 area
would add significant costs that would need to be factored into the SDC project list, potentially increasing
housing costs. The portions of Scenarios 2, 3, and 4 outside the Urban Growth Boundary would not be built by
development and would need to be funded through a Capital Improvement Project, likely from MSTIP or other
regional sources. This would potentially have implications for the funding strategy and timing relative to
development, but the greater impact is likely on the limited regional funds available for construction and
maintenance of transportation infrastructure in an increasingly constrained fiscal environment.
In Scenarios 2, 3, and 4, some amount of right-of-way would need to be reserved for the Tile Flat Road and
Mountainside Way extensions. This will leave undeveloped corridors, and the development design will need to
determine the form of these corridors in the interim (e.g., closed to the public, open as trail corridors, interim
bike/ped bridges at stream crossing locations, etc.). Despite a potentially long-time horizon to complete the
road extensions, having a long-term plan for a future road could inhibit construction of bike/ped connections
that could better serve the area in the near-term.
Evaluation
Scenario 1 allows development to be phased until a critical mass of development triggers the need for internal
stream crossings. It has the least amount of dedication required but some small impacts on the development
potential on Vandermost Road. Scenarios 2, 3, and 4 bring forward infrastructure costs – particularly the bridge
crossings – in order to meet regional traffic needs. These scenarios also require additional dedication and right-
of-way to be preserved until these extensions can be constructed in the future.
Evaluation of Tile Flat Extension Scenarios
June 2025
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TABLE 23 : EVALUATION OF LAND USE AND DEVELOPMENT IMPACTS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Funding and Timing Lowest cost
scenario needed
for development
Potential
implications on
funding strategy
and timing
Potential
implications on
funding strategy
and timing
Highest costs with
implications on
funding strategy
and timing
Ideal definition –
costs contained to
those supported by
development
Right-of-Way Needs Least amount of
dedication for ROW
and setbacks
Additional
dedication for ROW
and setbacks
Additional
dedication for ROW
and setbacks
Additional
dedication for ROW
and setbacks Ideal definition –
ROW and
dedications limited
to what is needed
to support RT 2.0
development
Impacts on
Development Yield
Least dedication
may be offset by
limited access
impacting
development scale
on Vandermost
Additional
dedication would
have some but not
significant impact
on yield
Additional
dedication and
limited access
could impact
development scale
on Vandermost
Additional
dedication would
have some but not
significant impact
on yield
Ideal definition –
least impact to
development yield
Overall
Performance for
Land Use and
Development
Costs can be
supported by
development,
potential minor
impact on
development
yield on
Vandermost
Higher costs may
have implications
on funding
strategy. Some
additional
dedication needs
Higher costs may
have implications
on funding
strategy. Some
additional
dedication needs
and potential
impacts on
development
yield on
Vandermost
Highest costs
may have
significant
implications on
funding strategy.
Some additional
dedication needs
Ideal definition –
least impact to
development with
costs contained to
those supported by
development
C. Order-of-Magnitude Infrastructure Costs and Funding Implications
This metric compares order-of-magnitude costs for full multimodal network buildout and the implications for
project funding.
Methodology
The analysis applied unit costs to the anticipated cross-sections, stream crossings, and intersections forms to
develop a cost estimate for each scenario. A qualitative assessment was also made on the potential funding
implications for each scenario based on expected project delivery.
Evaluation of Tile Flat Extension Scenarios
June 2025
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Results
Estimated infrastructure costs and cost considerations are included in Table 25. Scenario 1 includes less new
roadway and only two stream crossings and is the lowest cost scenario. Scenarios 2, 3, and 4 increase the length
of roadway, number of intersections and approaches, and require additional stream crossing(s) to extend Tile
Flat Road and/or Mountainside Way respectively. Scenarios 2 and 3 are almost double the cost of Scenario 1.
Scenario 4 requires the most new roadway, intersections, intersection approaches, and a total of four stream
crossings and is approximately 180% more expensive than Scenario 1.
In addition, the ability for private development to construct the roadways with cost-sharing through System
Development Charge (SDC) and/or Transportation Development Tax (TDT) credits varies for segments within RT
2.0 compared to those that extend outside the UGB. Segments that cannot be built by private development
must be built as a Capital Improvement Plan (CIP) project and funded in full through SDCs, TDT, and/or other
public sources, increasing the need for constrained transportation system construction and maintenance funds.
In addition, because these segments are serving a regional purpose, it is likely not appropriate to impose their
cost on development in RT 2.0, meaning that their construction would require contributions from county- or
city-wide sources. The city has limited funds available for the construction and maintenance of facilities already
listed in its Transportation System Plan, and the new prioritization framework and constrained project list
requirements of the Transportation Planning Rule in the Climate Friendly and Equitable Communities updates
means that the city has less dollars available in total for vehicle-centered projects, further impacting the ability
to maintain and improve existing facilities.
TABLE 24 : STREET NETWORK QUANTITY ASSUMPTIONS
CATEGORY ASSUMPTIONS
Total Length of new Collector Roadways (includes the total length
of Tile Flat Road and/or Mountainside Way under each scenario)
Scenario 1: 1.06 miles
Scenario 2: 1.69 miles
Scenario 3: 1.59 miles
Scenario 4: 2.22 miles
# of Stream Crossings Scenario 1: 2
Scenario 2 and 3: 3
Scenario 4: 4
# of Roundabouts Scenario 1: 0
Scenario 2 and 3: 1
Scenario 4: 2
# of new Approaches at Signalized Intersection Scenario 1: 2
Scenario 2 and 3: 3
Scenario 4: 4
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TABLE 25 : ESTIMATED INFRASTRUCTURE COSTS
Evaluation
Table 26 summarizes the evaluation of cost and funding implications. Scenario 1 has the lowest transportation
infrastructure cost. Scenarios 2, 3, and 4 have higher or much higher costs and may also require CIP projects and
contributions from county- or city-wide funding sources.
SCENARIO ROADWAY COSTS COST CONSIDERATIONS
A $18,500,000 • All roadway segments are within RT 2.0 and may be able to
be built by development (with cost-sharing through SDC
and/or TDT credits).
B $37,500,000 • Extending Tile Flat Road results in a 103% increase in cost for
additional and enhanced right-of-way and design and an
additional stream crossing.
• Tile Flat Road extension outside the UGB would likely require
a CIP project and contributions from county- or city-wide
funding sources.
C $33,000,000 • Extending Mountainside Way results in a 78% increase in cost
for additional and enhanced right-of-way and design and an
additional stream crossing.
• Mountainside Way extension outside the UGB would likely
require a CIP project and contributions from county- or city-
wide funding sources.
D $52,000,000 • Extending Tile Flat Road and Mountainside Way results in a
181% increase in cost for additional and enhanced right-of-
way and design and two additional stream crossings.
• Tile Flat Road and Mountainside Way extensions outside the
UGB would likely require CIP projects and contributions from
county- or city-wide funding sources.
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TABLE 26 : EVALUATION OF COST AND FUNDING IMP LICATIONS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Order-of-Magnitude Cost $18.5 million
(lowest)
$37.5 million
(+103%)
$33 million
(+78%)
$52 million
(+181%) Ideal definition – lowest cost
Need for CIP project and/or
contributions from county- or
city-wide funding sources
No Yes Yes Yes
Ideal definition – costs
contained to those supported
by development
Overall Performance for
Cost and Funding
Lowest cost
and no need
for CIP,
County, or City
funding
sources
Approximately
double the cost
of Scenario 1
and may need
CIP, County, or
City funding
sources
Higher cost
compared to
Scenario 1 and
may need CIP,
County, or City
funding
sources
Approaching
triple the cost
of Scenario 1
and may need
CIP, County, or
City funding
sources
Ideal definition – lower costs
contained to those supported
by development
D. Timing, Phasing, and Project Cost
This metric looks at the potential timing for constructing different street segments and stream crossings and the
implications on development phasing and infrastructure project delivery (e.g., public vs. private). It also
considers the implications of future proofing the construction of streets to a higher standard in advance of and
with the unknown of a Tile Flat Road extension.
Methodology
The analysis considered:
• Elements of the primary street network that may need to be accelerated to support a regional traffic
function in advance of their development need.
• Additional elements of the primary street network scenarios that are beyond the needs of the RT 2.0
development.
Results
Scenario 1 allows for development in RT 2.0 West to occur in four independent phases:
• The area accessed by extending Bull Mountain Road west of Roy Rogers Road.
• The area accessed by extending Jean Louise Drive west of Roy Rogers Road.
• The area accessed by extending Mountainside Way south of Scholls Ferry Road.
• The area accessed along Vandermost Road.
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These areas could develop independently with primary and secondary connections to the arterial street network
and over time be connected internally with the construction of the stream crossings north and south of Jean
Louise Drive once a critical mass of development triggers the need for internal circulation.
Extending Tile Flat Road and/or Mountainside Way (Scenarios 2, 3, and 4) may bring forward the need to
construct the primary street network and these two primary stream crossings before development can support
them and will require one or two additional stream crossings that are not required for development of RT 2.0
West. This raises the question of who funds the accelerated need for this infrastructure and the additional
stream crossing(s) outside of the RT 2.0 West development schedule.
TABLE 27 : TIMING, PHASING, AND PROJECT COST IMPACTS
SCENARIO IMPACTS
A • Elements of the primary street network could be constructed in each sub-area to
support development until a critical mass of development triggers the need for the 2
primary stream crossings to complete internal circulation.
• Regional traffic need may accelerate construction costs for the primary street network
and primary stream crossings.
• No additional right-of-way needs to be preserved along the Tile Flat Road and
Mountainside Way extensions beyond that needed for local street circulation.
B • Regional traffic need may accelerate construction costs for the primary street network
and primary stream crossings.
• Extending Tile Flat Road may bring forward the need to construct the primary street
network and the 2 primary stream crossings before development can support them.
This scenario also requires an additional stream crossing that is not needed as part of
the base development schedule included in Scenario 1.
• Right-of-way will need to be preserved sufficient for a collector street to be built along
the Tile Flat Road alignment. This will require an easement or road stub to be
maintained until this connection is funded.
C • Regional traffic need may accelerate construction costs for the primary street network
and primary stream crossings.
• Extending Mountainside Way may bring forward the need to construct the primary
street network and the 2 primary stream crossings before development can support
them. This scenario also requires an additional stream crossing that is not needed as
part of the base development schedule included in Scenario 1.
• Right-of-way will need to be preserved sufficient for a collector street to be built along
the Mountainside Way Extension alignment. This will require an easement or road stub
to be maintained until this connection is funded.
D • Regional traffic need may accelerate construction costs for the primary street network
and primary stream crossings.
• Extending Tile Flat Road and Mountainside Way may bring forward the need to
construct the primary street network and the 2 primary stream crossings before
development can support them. This scenario also requires 2 additional stream
crossings that are not needed as part of the based development schedule included in
Scenario 1.
• Right-of-way will need to be preserved sufficient for collector streets to be built along
the Tile Flat Road and Mountainside Way Extension alignments. This will require
easements or road stubs to be maintained until this connection is funded.
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Evaluation
Scenario 1 allows development to be phased until a critical mass of development triggers the need for internal
stream crossings. Scenarios 2, 3, and 4 bring forward the need for these costs to meet regional traffic needs.
They will also require right-of-way to be preserved until these extensions can be constructed in the future.
TABLE 28 : EVALUATION OF TIMING, PHASING, AND PROJECT COST IMPACTS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Timing, Phasing, and
Project Cost Impacts
Phasing can be
structured to
delay costs
Additional
stream
crossing may
bring forward
costs
Additional
stream
crossing may
bring forward
costs
Two additional
stream
crossings may
bring forward
costs
Ideal definition – development
can be phased to delay
infrastructure costs
E. Fire, Life, and Safety
This metric compares the fire, life, and safety needs for each scenario including access, connectivity, response
time, and development impacts (e.g., turnaround and circulation, building needs, etc.).
Methodology
The analysis includes a qualitative assessment of:
• Connectivity of the street network and if development areas have more than one access and can be
served by emergency routes from multiple directions.
• Design and development considerations, e.g., cross-section and turnaround needs for emergency
vehicles, building needs, etc.
• Potential impact to emergency response times due to increased internal traffic volumes.
These considerations are summarized in Table 29.
Results
Table 29 shows that Scenario 1 provides multiple accesses to most of the RT 2.0 West development and
emergency response from multiple directions. Without the extension of Tile Flat Road, development on
Vandermost Road would have a single access. Street design in that area will need to consider circulation and/or
turnaround needs for emergency vehicles. Scenario 3 would be similar. Development potential along
Vandermost Road is limited and will likely be below the 30 one- and two-family dwelling units where a second
access is required by the Oregon Fire Code. These dwellings will need to be equipped throughout with an
approved automatic sprinkler system. Given the low development potential, this impact is not considered
significant. However, it does provide an additional emergency access route to the rest of RT 2.0 West via the
extension of Mountainside Way to Perth Road.
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TABLE 29 : FIRE, LIFE, SAFETY CONSIDERATIONS
SCENAR
IO
ACCESS AND CONNECTIVITY DESIGN AND
DEVELOPMENT
A • Multiple accesses and emergency response is possible from
multiple directions for the majority of RT 2.0 West.
• Interim right-in/right-out access may be needed as secondary
access to the arterial network to support phased development
before internal connections / stream crossings are built.
• Development on Vandermost Road will be served by a single
access and limited to 30 one- or two-family dwellings fitted
with an approved automatic sprinkler system.
• This scenario has the lowest internal traffic volumes that may
help reduce response time.
• Street design will need
to consider circulation
or turnaround for
emergency vehicles on
Vandermost Road.
• Street design features
(e.g., medians,
protected bikeways,
etc.) to be coordinated
with Tualatin Fire &
Rescue.
B • Multiple accesses and emergency response is possible from
multiple directions for all of RT 2.0 West – including an
additional emergency response route to the northwest with the
extension of Tile Flat Road.
• Interim right-in/right-out access may be needed as secondary
access to the arterial network to support phased development
before internal connections / stream crossings are built.
• Development on Vandermost Road will be connected to the
rest of RT 2.0 providing secondary access for emergency
response.
• Increased internal traffic volumes may increase response time.
• Street design features
(e.g., medians,
protected bikeways,
etc.) to be coordinated
with Tualatin Fire &
Rescue.
C • Multiple accesses and emergency response is possible from
multiple directions for the majority of RT 2.0 West – including
an additional emergency response route to the south with the
extension of Mountainside Way.
• Interim right-in/right-out access may be needed as secondary
access to the arterial network to support phased development
before internal connections / stream crossings are built.
• Development on Vandermost Road will be served by a single
access and limited to 30 one- or two-family dwellings fitted
with an approved automatic sprinkler system.
• Some increase in internal traffic volumes may increase
response time.
• Street design will need
to consider circulation
or turnaround for
emergency vehicles on
Vandermost Road.
• Street design features
(e.g., medians,
protected bikeways,
etc.) to be coordinated
with Tualatin Fire &
Rescue.
D • Multiple accesses and emergency response is possible from
multiple directions for all of RT 2.0 West – including additional
emergency response route to the northwest and south with
the extensions of Tile Flat Road and Mountainside Way.
• Interim right-in/right-out access may be needed as secondary
access to the arterial network to support phased development
before internal connections / stream crossings are built.
• Development on Vandermost Road will be connected to the
rest of RT 2.0 providing secondary access for emergency
response.
• Increased internal traffic volumes may increase response time.
• Street design features
(e.g., medians,
protected bikeways,
etc.) to be coordinated
with Tualatin Fire &
Rescue.
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Scenarios 2 and 4 would provide additional access via the Tile Flat Road extension and allow emergency
response from the northwest. These scenarios also provide a second emergency access to any development on
Vandermost Road. Scenarios 3 and 4 would provide an additional emergency response route from the south
with the extension of Mountainside Way to the Roy Rogers Road & Perth Road intersection.
All scenarios will need to consider fire and emergency access during the phased buildout of the development. If
development occurs before the stream crossings are constructed, secondary access points will be needed with
interim right-in/right-out access to the arterial network.
As the number of access points increases so does traffic volume internal to the development, which could offset
some response time savings.
Street design features such as medians, protected bike lanes, and other features that reduce street widths will
need to be considered in relation to the Fire Code and in consultation with Tualatin Valley Fire & Rescue.
Evaluation
Table 30 shows that all scenarios address fire, life, and safety needs. Although Scenarios 1 and 3 do not include
the Tile Flat Road extension, the resulting single access to development on Vandermost Road is not considered
significant given that development potential in that area is likely less than the threshold needed for a secondary
access and can be addressed with emergency vehicle circulation or turnaround and automatic sprinkler systems.
While having additional emergency access is always helpful, Scenarios 1 and 3 provide emergency response
routes from multiple directions and via multiple access points and as such meet fire, life, and safety needs.
There is some potential for increased response under Scenarios 2 and 4, however, these increases are not
expected to be significant.
TABLE 30 : EVALUATION OF FIRE, LIFE, AND SAFETY IMPACTS
SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Multiple Access Points
Available
Multiple access
points for
majority of RT
2.0 West but
single access
may limit
development on
Vandermost^
Multiple access
points for all of
RT 2.0 West
Multiple access
points for
majority of RT
2.0 West but
single access
may limit
development on
Vandermost^
Multiple access
points for all of
RT 2.0 West
Ideal definition – all areas of
development have multiple
access points
Primary Directions for
Emergency Response
3 4 3 4
Ideal definition – more
directions may reduce
response times
Potential for Response Time
Delay due to Traffic
Lowest traffic
volumes will
result in lowest
transit delays
Higher traffic
volumes on
Mountainside
Way will increase
transit delay
Slightly higher
traffic volumes
on Mountainside
Way but similar
to Scenario 1
Highest traffic
volumes on
Mountainside
Way will increase
transit delay
Ideal definition – no delay to
emergency response times
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SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
compared to
Scenario 1
compared to
Scenario 1
Overall Performance Meets
Fire, Life, and Safety Needs
Meets fire, life,
safety needs
with some
impacts on
development
on Vandermost
Meets fire, life,
safety needs
with multiple
accesses and
response
directions.
Higher traffic
volumes may
impact
emergency
response time
Meets fire, life,
safety needs
with some
impacts on
development
on Vandermost
Meets fire, life,
safety needs
with multiple
accesses and
response
directions.
Higher traffic
volumes may
impact
emergency
response time
Ideal definition – meets fire,
life, safety with minimal
impact on development yield
and response times
* Does not consider potential development on Vandermost Road, which is considered separately.
^ This will limit development to under 30 one- and two-family dwellings that will need to be fitted with an approved automatic sprinkler system. It will also
require circulation or turnaround area for emergency vehicles. These requirements meet the Fire Code and are not considered significant.
Evaluation of Tile Flat Extension Scenarios
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5. EQUITY
The following provides an analysis of potential equity impacts across the primary street network scenarios.
A. Equitable Benefits
This metric compares who benefits and who is impacted under each of the network scenarios. The analysis
compares impacts to potential residents of RT 2.0.
Methodology
Qualitative analysis of potential impacts to equity communities as mapped on the Oregon Social Equity Web
App.
It is difficult to measure the equitable distribution of impacts given the demographics of people that might move
to RT 2.0 are unknown. However, the development is intended to include a mix of housing types available to a
variety of income levels that could attract populations that face disparity in their access to health,
transportation, education, housing, and wealth. As a comparison, although not fully built out, RT 1.0 between
Scholls Ferry Road and Bull Mountain Road is designated as “low-medium disparity” when compared to state
averages with respect to age, ability, income, language, and race/ethnicity (which are identified as predictors of
disparity).
If similar demographics are attracted to RT 2.0, then it will be important to minimize negative impacts from
emissions and noise exposure, increased crash risk, reduced access to convenient and low-cost transportation,
reduced access to parks, open space, and local destinations, housing affordability, and climate resilience in order
to reduce the potential for these factors to increase disparities in access to health, transportation, education,
housing, and wealth.
Results & Evaluation
Overall, Scenario 1 would minimize potential impacts to more vulnerable future residents by minimizing the
amount of traffic on the internal street network (reducing exposure to emissions, noise, and crash risk) and
providing comfortable and low-cost transportation options that can access local parks, commercial areas,
schools, etc. Scenario 1 also has the lowest infrastructure cost which would bring down overall development
costs and may reduce the cost of housing for future residents. With the fewest stream crossings and roadway
footprint of the scenarios, Scenario 1 would preserve the greatest amount of natural resources in the project
area. This contributes to improved climate resilience outcomes for future residents of RT 2.0 West such as
increased carbon sequestration and better adaptation to climate change impacts like drier summers, hotter
temperatures, and more intense rainfall events.
Scenario 3 that extends Mountainside Way to Perth Road would provide a benefit to residents in terms of
increasing access to destinations in parts of RT 1.0, RT 2.0, and Kingston Terrace. However, it would result in
higher traffic volumes on the internal street network, increasing exposure to crash risk, noise, and emissions for
future residents of RT 2.0 West. This could also increase travel time for future transit service, a critical service for
lower-income individuals, youth, and people with mobility limitations to reach key destinations within RT 2.0
and the surrounding region.
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TABLE 31 : EVALUATION OF POTENTIAL IMPACTS ON DISPARITY
PM PEAK HOUR VMT SCENARIO 1 SCENARIO 2 SCENARIO 3 SCENARIO 4
Emissions and Noise Exposure Lowest internal
traffic volumes
Higher traffic
volumes than
Scenario 1
Slight increase in
traffic volumes
compared to
Scenario 1
Highest traffic
volumes compared
to Scenario 1 Ideal definition – lowest
exposure
Crash Risk Lowest VRU
crash exposure
VRU crash
exposure
somewhat higher
than Scenario 1
VRU crash
exposure
somewhat higher
than Scenario 1
VRU crash
exposure
considerably
higher than
Scenario 1
Ideal definition – lowest crash
exposure
Access to Convenient and Low-
Cost Transportation
Good access to
transit and a
well-connected
active
transportation
network.
Lowest transit
delays
Good access to
transit and a
well-connected
active
transportation
network.
Increased transit
delay
Potential for
increased transit
routes and
additional active
transportation
connections. Low
transit delays
Potential for
increased transit
routes and
additional active
transportation
connections.
Highest transit
delays
Ideal definition – access to
transit and well-connected
active transportation
Access to Parks, Open Space,
and Local Destinations
Good access to
parks, open
space, and local
destinations
Good access to
parks, open
space, and local
destinations
Potential for
increased access
to these
destinations via
Perth
Potential for
increased access to
these destinations
via Perth Ideal definition – well-
connected access to these
destinations
Housing Affordability Lowest
infrastructure
costs may
increase
housing
affordability
Higher
infrastructure
costs compared
to Scenario 1
may decrease
housing
affordability
Higher
infrastructure
costs compared to
Scenario 1 may
decrease housing
affordability
Highest
infrastructure costs
compared to
Scenario 1 may
decrease housing
affordability
Ideal definition – lowest
infrastructure costs resulting in
lower housing prices
Natural Resource Impacts and
Climate Resilience
Fewest stream
crossings, some
impact to trees,
lowest
impervious
surface
Additional
stream crossing,
some impact to
trees, potential
wetlands impact,
increased
impervious
surface
Additional stream
crossing, some
impact to trees,
increased
impervious
surface
Two additional
stream crossings,
some impact to
trees, potential
wetlands impact,
highest impervious
surface
Ideal definition – minimal
impact to streams, trees,
wetlands, and impervious
surface
Overall Impacts on
Populations Facing Disparity
Lowest
exposure to
emissions,
noise, and
crash risk but
some impacts
from climate
resilience
Higher
exposure to
emissions,
noise, and
crash risk,
impacts to
housing
affordability
and climate
resilience
Higher exposure
to emissions,
noise, and crash
risk, impacts to
housing
affordability
and climate
resilience.
Increased
connectivity
Highest
exposure to
emissions, noise,
and crash risk;
impacts to
housing
affordability and
climate
resilience.
Increased
connectivity
Ideal definition – no impacts to
vulnerable populations
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Scenarios 2 and 4 that extend Tile Flat Road would increase vehicular access to the arterial street network,
particularly to regional destinations northwest of RT 2.0. However, it would result in higher traffic volumes on
the internal street network increasing exposure to crash risk, noise, and emissions for future residents of RT 2.0
West. This could also increase travel time for future transit service. Increased development costs associated with
these two scenarios may have a negative impact on housing affordability in RT 2.0, and the significant added
impact to natural resources is expected to lessen climate resilience outcomes for future residents.
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APPENDICES
Appendix A – Bicycle Level of Traffic Stress (BLTS) Design Requirements
TABLE A1. SEGMENT BLTS 1 DESIGN CRITERIA
Based on the ODOT BLTS methodology outlined in the Analysis Procedures Manual Chapter 14 – Section 14.4 and incorporating
best practice principles from the 2024 AASHTO Guide for the Development of Bicycle Facilities
FACILITY DESIGN CRITERIA
Shared Use Path Assuming minimum standards per 2024 AASHTO Guide for the
Development of Bicycle Facilities (Table 6-3).
Assuming a peak hour volume on the shared use path between 300 to 500
bph:
• Practical minimum width: 11’ (constrained scenarios only).
• Recommended lower limit: 12’.
• Recommended upper limit: 15’.
• Recommended practical maximum is 16’.
Separated Bike Lanes Assuming minimum standards per 2024 AASHTO Guide for the
Development of Bicycle Facilities.
Facility type: One-Way Separated Bike Lanes Between Sloped Curb, at
Sidewalk Level, or Adjacent to Curb with Gutter widths (bike lane only,
excluding curb widths):
• 5.5’-7.5’ width (< 150 peak hour directional bicyclist volume).
• 7.5’-9’ width (150-750 peak hour directional bicyclist volume).
• ≥ 9’ width (> 750 peak hour directional bicyclist volume).
Bike Lane with Adjacent
Parking Lane
For segments of the primary street network with on-street parking:
• ≥ 15’ bike lane + parking lane width.
• Bike lane should include buffers to both the traffic and parking
lanes.
Bike Lane with No Adjacent
Parking Lane*
For segments of the primary street network without on-street parking:
• ≥ 7’ buffered bike lane.
• Note: while the ODOT methodology to achieve segment BLTS 1
(Exhibit 14-5) permits a 7’ minimum on-street buffered bike lane
(inclusive of buffer) for a 2-lane, 25 mph roadway, per the 2024
AASHTO Guide for the Development of Bicycle Facilities, this
facility would not achieve the highest level of comfort and be
considered below the standard of separated bike lanes and shared
use path alternatives.
Neighborhood Greenways No centerline, 750 - ≤1,500 ADT, local streets
Distance Between Crossing
Opportunities
≤ 0.10 mi (~500 ft)
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TABLE A2. INTERSECTION BLTS 1 DESIGN CRITERIA
Based on the ODOT BLTS methodology outlined in the Analysis Procedures Manual Chapter 14 – Section 14.4 and incorporating
best practice principles from the 2024 AASHTO Guide for the Development of Bicycle Facilities
INTERSECTION
FEATURE
DESIGN CRITERIA
Right Turn Lanes Bike lanes may not jog across or to the left of a dedicated right turn lane to be
considered BLTS 1. There are two scenarios to achieve BLTS 1 at intersections
with on-street bike lanes to the right of dedicated right turn lanes:
• A bike signal to separate bike and vehicular right turn movements.
• A protected intersection design where bikes shift right, away from the
curbline, and cross the intersection adjacent to the pedestrian crossing,
with a bike signal or with the pedestrian signal.
Left Turn Lanes Two-stage left turn maneuver - either with a protected intersection or with bike
box/left turn queue box markings.
Unsignalized Crossings
without a Median
For segments with ≤ 3 total through and turning lanes, these crossings are
appropriate when:
• ≤ 1,200 ADT on local streets.
• ≤3,000 ADT on collector streets.
Unsignalized Crossing
with a Median
These crossings should be used for streets with higher volumes than above and
should consist of:
• 1 crossing lane per direction.
• Median refuge ≥ 10’ width.
Roundabout Crossings Bicyclists should be provided a shared (with pedestrians) or separate pathway
around the roundabout outside the roadway. The following criteria should be
met:
• Single lane entry or exit with splitter island refuge ≥ 10’ width.
• 1 circulating lane.
• Non-tangential entry (to create vehicle deflection).
• Separate bike and pedestrian facilities or shared use path width ≥ 10’
(2024 AASHTO Guide for the Development of Bicycle Facilities, 11.10.3).
• Per the 2021 AASHTO Guide for the Development of Pedestrian Facilities
(Figure 3-39) and ODOT BLTS (pg. 21), 20’-30’ setback required from
edge of circulating roadway to crossing to allow for reaction time for
exiting vehicles while minimizing out-of-direction travel.
• To transition from on-street bike lanes to/from the sidewalk level
pathway around the roundabout, separate bike ramps or shared
bike/pedestrian ramp with > 10’ width are required.
Signalized Crossings (at
Arterials)
To maintain BLTS 1, signalized intersections require:
• Bike detection or activation or pre-timed signals.
• No permissive left or right turns.
• Bike signals and/or bike turn boxes to treat right- and left-turn conflicts.
• Protected intersection treatments.
Other Criteria No frequent bike lane blockages due to transit, loading, etc.
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Appendix B – Pedestrian Level of Traffic Stress (PLTS) Design Requirements
TABLE B1. SEGMENT PLTS 1 DESIGN CRITERIA
Based on the ODOT PLTS methodology outlined in the Analysis Procedures Manual Chapter 14 – Section 14.5.
FACILITY DESIGN CRITERIA
Sidewalk Condition Good (new construction)
Sidewalk Width ≥ 6 typical, ≥ 8’ in higher foot-traffic and commercial areas
Physical Buffer Type Landscaped (with or without street trees) or solid surface. Solid
surface could include a sidewalk-level bike lane, hardscape with
a surface material change such as pavers or stamped concrete,
hardscape with planters, street furniture, etc.
Total Buffering Width ≥ 10’ that includes the width of the landscaped or solid surface
buffer plus the width of any parking, shoulder, or bike lane.
Distance Between Crossing Opportunities ≤ 0.10 mi (~500 ft)
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TABLE B2 . INTERSECTION PLTS 1 DESIGN CRITERIA
Based on the ODOT PLTS methodology outlined in the Analysis Procedures Manual Chapter 14 – Section 14.5.
INTERSECTION FEATURE DESIGN CRITERIA
Unsignalized Crossings at Collectors or
Local Streets
All ramps to be designed as standard ramps.
Crossing types:
• 2 crossing lanes with no median refuge is acceptable
for ≤ 30 mph and ≤ 5,000 vpd.
• 1 crossing lane in each direction with median refuge is
acceptable for ≤ 30 mph and ≥ 5,000 vpd. Requires ≥
10’ median refuge width.
The following items may improve the PLTS:
• Enhanced markings and signage.
• Illumination.
• Pedestrian activated beacons (e.g., RRFB).
• In-street signs.
• Curb extensions.
• Raised crosswalks.
• Standard 12” flashing beacons.
Roundabout Crossings Single lane entry or exit crossings with splitter island refuge ≥
10’ width.
Signalized Crossings (at Arterials) Signalized crossings will generally be PLTS 1. However, no
permissive left or right turns are allowed.
Pedestrian signal countdown features are required.
Lighting Adequate illumination of the intersection.
Other Criteria PLTS 1 is not achieved if any of the following conditions exist:
• Crossing distance ≥ 72’ or more than 6 lanes (or
equivalents such as a parking lane).
• Non-standard geometry (such as more than 4 legs or
highly skewed approaches).
• Closed or limited crosswalk legs.
• Free-flow or yield-controlled channelized right turns.
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Appendix C – Walkshed Analysis Maps
FIGURE C1: HALF -MILE WALKSHED FOR SCENARIO 1 .
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FIGURE C2: HALF -MILE WALKSHED FOR SCENARIO 2.
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FIGURE C3: HALF -MILE WALKSHED FOR SCENARIO 3.
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FIGURE C4: HALF -MILE WALKSHED FOR SCENARIO 4.
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FIGURE C5: ONE -MILE WALKSHED FOR SCENARIO 1.
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FIGURE C6: ONE -MILE WALKSHED FOR SCENARIO 2.
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FIGURE C7: ONE -MILE WALKSHED FOR SCENARIO 3.
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FIGURE C8: ONE -MILE WALKSHED FOR SCENARIO 4.
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Appendix D – Primary Street Impervious Surface Area Calculations
TABLE D 1. PRIMARY STREET IMPERVIOUS SURFACE CALCULATIONS
SCENARIO CROSS -SECTION
HARDSCAPE
WIDTH
ASSUMPTIONS LENGTH
OF
SEGMENT
IMPERVIOUS
SURFACE
AREA
A SUP one side (16’),
sidewalk opposite
side (8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 52’
Assumes 12’ lanes for roadway, not inclusive of
gutter. Does not account for any intersection
widening for turn lanes.
Does not account for curb ramp/corner
hardscape.
Assumes landscaped buffer between curb and
SUP/ sidewalk.
Does not account for hardscape, concrete pads
on sidewalk for bus stop locations, potential
parking/loading zones, or choice of hardscape
buffer for a tactile warning strip or street
furniture.
1.05 mi
or 5,544
ft
~288,300
SQFT
Unidirectional bike
lanes both sides
(sidewalk-level or
intermediate level)
both sides (8’ + 8’),
sidewalks both
sides (8’ + 8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 60’
Assumes 12’ lanes for roadway, not inclusive of
gutter. Does not account for any intersection
widening for turn lanes.
Does not account for curb ramp/corner
hardscape.
Assumes landscaped buffer between curb and
sidewalk-level bike lanes and between sidewalk-
level bike lanes and sidewalk.
Does not account for hardscape, concrete pads
on sidewalk for bus stop locations, potential
parking/loading zones, or choice of hardscape
buffer for a tactile warning strip or street
furniture.
Does not assume an intermediate-level
bikeway.
1.05 mi
or 5,544
ft
~332,600
SQFT
B SUP one side (16’),
sidewalk opposite
side (8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 52’
See previous. 1.69 mi
or 8,923
ft
~464,000
SQFT
Unidirectional bike
lanes both sides
(sidewalk-level or
intermediate level)
both sides (8’ + 8’),
sidewalks both
sides (8’ + 8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 60’
See previous.
1.69 mi
or 8,923
ft
~535,400
SQFT
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SCENARIO CROSS -SECTION
HARDSCAPE
WIDTH
ASSUMPTIONS LENGTH
OF
SEGMENT
IMPERVIOUS
SURFACE
AREA
C SUP one side (16’),
sidewalk opposite
side (8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 52’
See previous. 1.68 mi
or 8,870
ft
~461,200
SQFT
Unidirectional bike
lanes both sides
(sidewalk-level or
intermediate level)
both sides (8’ + 8’),
sidewalks both
sides (8’ + 8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 60’
See previous.
1.68 mi
or 8,870
ft
~532,200
SQFT
D SUP one side (16’),
sidewalk opposite
side (8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 52’
See previous. 2.32 mi
or 12,250
ft
~637,000
SQFT
Unidirectional bike
lanes both sides
(sidewalk-level or
intermediate level)
both sides (8’ + 8’),
sidewalks both
sides (8’ + 8’), total
asphalt paved
roadway (24’), curb
and gutter (2’ + 2’)
= 60’
See previous.
2.32 mi
or 12,250
ft
~735,000
SQFT