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11/06/1986 - Packet � - ,. *VOW CITY OF TIGARD �woo, TRANSPORTATION ADVISORY COMMITTEE MEETING AGENDA November 6. 1986 — Z:00 POM Tigard City Hall Members: SULLIVA FUNK_____ PADGETT HUMME SCHWEITZ_____ 0WENS_____ PHEIGTER___...... l . DISCUSSION OF SOUTHWEST CORRIDOR STUDY DRAFT REPORT. 2. DISCUSSION OF TIGARD TRIANGLE TRAFFIC CIRCULATION REPORT. 3 . OTHER BUSINESS. 4. ADJOURN. /br172 TRANSPORTATION ADVISORY COMMITTEE 10/28/86 (Chamber Rep) Thomas J. Sullivan 620-8702 P.O. Box 23804 Tigard, OR 97223 (At Large) David Funk 620-5215 11452 SW 115th Avenue Tigard, OR 97223 (At Large) Mark Padgett /co chair 629-8474 11270 SW 95th Tigard, OR 97223 (S.E. of SW Dennis Hummel 643-5454 Pacific Hwy. ) 14975 SW 103rd X 331 Tigard, OR 97224 (N.W. of SW Joe Schweitz 238-4881 Pacific Hwy. ) 11020 SW Cottonwood Lane Tigard, OR 97223 (Planning Comm. Rep) Bonnie Owens 292-4488,or 12450 SW SummercrestDrive 684-1583 Tigard, OR 97224 (High School Rep) Kathy Pheister 17333 SW Rivendale Tigard, OR 97224 Staff Liaison - Randall Wooley, City Engineer Yw,r' fir✓' TRAFFIC ENGINEERING REPORT REVIEW OF STREET CLASSIFICATIONS RIVERWOOD LANE AND VICINITY November, 1986 1 Background On the City's Comprehensive Plan Transportation Map, currently Durham Road is shown as a major collector, 92nd Avenue is shown as a minor collector, and Riverwood Lane is shown as a minor collector. In addition, the plan calls for "connection of Riverwood Lane between 92nd and 108th." SW 108th Avenue shows no designation; however, the requirement for a Riverwood Lane connection implies that 108th should also be a minor collector, as it is the westerly connection between Riverwood Lane and Durham Road. The Tualatin River makes southward extension of the street system unlikely. A deep ravine to the west of 108th makes it impractical to extend Riverwood Lane west of 108th. A subdivision has been approved which will extend Riverwood Lane eastward to connect to 92nd Avenue. At the time the subdivision was approved, it was determined that it was not appropriate to extend Riverwood Lane east of 92nd Avenue. The existing portions of Riverwood Lane have been developed to local street standards. Scope of This Review Residents of Riverwood Lane and NPO #6 have questioned the need for Riverwood Lane to be a minor collector. This review is to address that question. The study area is bounded by Durham Road on the north, 92nd Avenue on the east, the Tualatin River on the south, and the 108th/113th ravine on the west, excluding properties with access only to Durham Road. Assumptions The following assumptions have been made: 1. In existing subdivisions in the east portion of the study area, each vacant lot will be developed as one single—family residence; otherwise, the existing subdivisions will not change. 2. Subdivisions currently approved by the City or currently under review by the Planning Commission will be developed substantially as currently proposed, with one single—family residence on each lot. 3 . The remaining land will be developed at the maximum density allowed by the current zoning. Traffic Engineering Report CPA 11-86 Page 1 4. One additional access point will be provided to Durham Road, said access to be aligned with the existing 104th Avenue intersection. An existing City/County agreement for Durham Road allows no additional access points in the study area west of 104th. Under the agreement, an additional access point could be considered between 104th and Serena Court but preliminary planning indicates that such an access is unlikely to be developed. 5 Riverwood Lane will be extended eastward to connect with 92nd Avenue as planned. 6. Access to 108th Avenue will be provided at three or more points along 108th. All of the study area west of 108th will have its access from 108th. 7. There will be no need or demand for through traffic routes in the study area except on Durham Road and 92nd Avenue. The Tualatin River precludes north—south through traffic except for the 92nd access to Cook Park. Likewise, the 108th/113th ravine precludes east—west through traffic south of Durham Road. 8. Motorists will use the shortest route available to access Durham Road. Traffic Generation In predicting traffic volumes we have assumed 10 vehicle trips per day per single—family residence and 6 trips per day per apartment unit. These rates are based on national averages published by the Institute of Transportation Engineers in the report titled Trip Generations, Third Addition. In November, 1986, the City counted traffic volumes on the existing entrances to the subdivisions in the east portion of the study area. The counts showed average weekday traffic volumes (ADT) as follows: Location ADT Serena Court south of Durham 2249 Martha Street near 92nd 622 Millen Drive near 92nd 925 At the time of the traffic counts, these three streets provided the only access to an area with 376 existing single—family residences and with 8 additional single—family residences currently under construction. The counts indicate a traffic generation rate between 9.9 and 10. 1 trips per day per house, depending on whether we include those houses under construction. This appears to confirm the applicability of the national averages which we have used. Traffic Volume Predictions Based on the assumptions stated above, average weekday traffic volumes were predicted for the access points to each of the subareas shown on the attached map. The projected traffic volumes at full development are as follows: Traffic Engineering Report CPA 11-86 Page 2 Area Access Street Projected ADT (vehicles/day) A 108 Ave. 5840 B 108 Ave 1070 C 104 Ave 3217 D Serena Court 2240 E Martha St. 920 F Millen Dr. 690 G Riverwood Lane 330 Obviously, drivers will not always conform to the boundaries used in projecting traffic volumes. However, we can expect that the boundary crossovers will tend to be balanced; i.e. , the number of Area C drivers who use the Area D access route should roughly equal the number of Area D drivers using the Area C access point. The projected volumes are at the main access point to each area. At points further from the access point, traffic volumes will be lower. These estimates are based on the assumptions of maximum densities in future development of those areas currently undeveloped. Actual development is commonly less than the maximum density allowed; so, actual traffic volumes in the west part of the study area may be less than estimated. Discussion Area A: The projected traffic volume on 108th Avenue at Durham Road is greater than we usually see on local residential streets. Extra width for turn lanes may eventually be needed on the north portion of 108th Avenue. Area B: The projected traffic volumes on the south portion of 108th Avenue are within the levels commonly experienced on local residential streets. Area C: The projected volume for 104th Avenue at Durham Road is rather high for a local street. At the time that the easterly portion of Area C is developed, an additional traffic review should be done. Depending on the density of the actual development, it may be appropriate to consider an additional access point to Durham Road between 104th and Serena Court. Area D: No change is forecast in the traffic on Serena Court, as Area D is already fully developed. Area E: The traffic on Martha Street will increase as development occurs on the remaining vacant lots in the area. The projected volume is approximately the same as the current volume on Millen Drive. Area F: The traffic volume on Millen Drive is expected to be reduced somewhat when Riverwood Lane is extended to connect with 92nd Avenue. Traffic Engineering Report CPA 11-86 Page 3 Area G: The projectd traffic volume on Riverwood Lane at 92nd is within the range commonly accepted on residential streets. General: While we usually discourage through traffic in residential areas, it is still desirable to provide connections between adjoining residential areas. The connections have the advantages of (1) better dispersing of the residential traffic to multiple access points, (2) providing alternate access when a street is blocked by an emergency or a roadway repair, (3) providing for pedestrian circulation, and (4) allowing trips within the residential neighborhood to occur without the need to access a collector road. Recommendations Based on the above analysis, the following actions are recommended: 1 . Reclassify Riverwood Lane from minor collector street to local street. 2. Eliminate the requirement that Riverwood Lane connect directly to 108th Avenue. 3 . Designate 108th Avenue as a minor collector north of the proposed Kent Drive in Dover Landing Subdivision. 4. During review of current and future plats, provide for roadway connection between the various areas but avoid creating street alignments that appear as a through route between collector streets. 5. During review of future plats, include sufficient traffic analysis to evaluate the desirability of additional access points to 108th Avenue and to Durham Road Randall R. Wooley, P.E. City Engineer 2715P w t N 13.245 grp OREGON 99yoAlL R. Traffic Engineering Report CPA 11-86 Page 4 Iii11 1�1?i■onn soon 11=11`��IIII/1 • � �, p1111111►����;IIIA■ ■ iii �I ►I�. SIL.�,�� 11 w - ��■,� law 6LJ SO �� �� ♦ None �•r — ■■IP .00 lig i I��� -...r�� ���1 r j �• M1 MnI �Sim ■■ �Iil:rii .1 JIL �,jj Ka Ab all ` ,�`:� •�'� ��i ♦ Ali:'