What Must Be Included in a Transportation Impact Analysis?

1. All Transportation Impact Analyses must be signed and stamped by a Professional Traffic Engineer or Civil Engineer (with experience in traffic) actively registered in the State of Oregon by the Oregon State Board of Examiners for Engineering and Land Surveying (OSBEELS).
2. An executive summary discussing the development, the major findings of the analysis, and the mitigation measures proposed.  This must include a statement by the engineer that the resulting transportation network with the development and mitigation measures as proposed will provide adequate facilities for the public that meet all appropriate safety standards and practices.
3. A vicinity map showing the proposal in relation to the area transportation system
4. A complete description of the proposed development including a site plan, the nature and size of each proposed use (or reasonable worst-case scenario if use unknown), the proposed location, design, and traffic control of all site accesses, and the distance from each access to adjacent streets and/or accesses.
5. A description of the current and proposed (as known) land uses near the site including trip information for any properties that would share or gain access across the subject property.
6. A description of the transportation facilities in the study area including street names, functional classifications, jurisdiction, sidewalks, bike lanes, facilities for people with disabilities, transit routes, traffic control, lane configurations, etc., and any planned improvements in the area.
7. Existing traffic volumes measured within the last 12 months during design conditions.  Include hourly counts for intersections and daily counts for road segments.
8. Crash data and crash history analysis (including breakdown by severity and type, observed intersection crash rate per million entering vehicles) for the most recent available five-year period (from the Oregon Department of Transportation).
9. Identification of the analysis periods – the time(s) with the most traffic issues and the time(s) when the proposed development would have the most impact or needs.  This is typically the morning and afternoon weekday peak hours and/or peaks of development traffic, but can include mid-day or weekend peak hours depending on the specific proposal.
10. Existing performance of the vehicular transportation system including Levels of Service (LOS) and Volume/Capacity (V/C) ratios for all intersections and street segments in the study area.  The LOS and V/C data shall be calculated using the current Highway Capacity Manual methodologies as approved by ODOT and calibrated to reflect observed site conditions through delay studies and other observations (not solely calculated from theoretical assumptions). 
11. Description of how calculation methods have been calibrated based on observed traffic data and the calibration that will be used for the forecast scenarios.
12. Evaluation of Existing conditions for walking, cycling, and people with disabilities for all streets and paths in the study area.  This evaluation should focus on providing connectivity to existing walking and biking routes and identify any gaps near or along key routes to the development.
13. The trip generation and distribution description (see above) for this development.
14. Trip generation figures for pending or approved developments in or affecting the study area (City staff can help provide data).
15. Forecast background traffic volumes in the year the development is planned to open.
16. Forecast performance (including LOS, V/C, etc.) with and without the proposed development in the year after it opens.
17. Evaluation of post-development conditions for walking, cycling, and people with disabilities for all street and path segments in the study area. This will include identifying impact and contribution by development for gaps in the bicycle and pedestrian network identified in step 12.  This includes forecast pedestrian and cyclist volumes and multi-modal level of service for each link.  Include evaluation of crossing needs along key walking routes, where applicable.  Include a listing of all locations where improvements are necessary to provide adequate facilities for pedestrians, cyclists, and people with disabilities traveling to and from the proposed development.
18. Forecast traffic volumes and transportation system performance in the horizon year and the planned opening years of any future phases of development.
19. Forecast pedestrian, cyclist and persons with disabilities conditions and needs in the future phase and horizon years.
20. Sight distance analysis of the proposed site access(es) based on AASHTO stopping sight distance.
21. Evaluation of proposed access locations compared to local access spacing standards and access locations specified in adopted codes or plans.
22. Evaluation of traffic signal warrants and turn lane warrants for site intersections and frontage roadways, where applicable.
23. Traffic flow, safety, and pedestrian/cyclist needs analysis of the proposed site access(es), including turn lane needs, queue lengths, channelization, turn restrictions, crossing needs, walking and rolling routes, turning movements for design vehicles, comparison with standards, and other operational and safety issues.
24. Evaluation of anticipated queuing at the study area intersections and site accesses and description of any potential locations where queues may overlap, block travel lanes or bike lanes, extend through crosswalks, intersections or across accesses, or otherwise cause issues.
25. When downstream deficiencies may impact upstream operations (i.e. queue spillback between intersections, turn lane queue block through lanes, etc.) during the peak 15 minutes of peak hour operations, evaluation of upstream operational performance shall include traffic simulation analysis utilizing SimTraffic, Vissim, or alternate software and methodology approved by City staff. Simulation analysis shall be developed and calibrated per the ODOT Analysis Procedures Manual and shall be undertaken to determine average and 95^th percentile queue length.
26. Evaluation of on-site parking, traffic flow, pedestrian, cyclist, and persons with disabilities accommodations and the adequacy thereof, and anticipated impact of the proposed development on nearby streets.  Identify plans and mitigation measures necessary to prevent offsite impacts, such as keeping site traffic queues from extending onto public streets.
27. Analysis as appropriate of any potential adverse or controversial effects of the proposed development, such as non-residential traffic through residential neighborhoods, effects on school zones, significant traffic increases on ‘quiet’ streets, or site traffic queues affecting public streets.
28. Listing of all intersections, segments, and locations that are projected to not meet City standards for traffic, safety, pedestrian, cyclist, or transit needs in the study area during the study timeframe.
29. Recommendation of necessary improvements to ensure an acceptable level of service for roadways of at least D and E for signalized and unsignalized intersections respectively, after future traffic impacts are considered (per Tualatin Development Code Chapter 74).  Include analysis verifying that these measures will bring the facilities up to appropriate standards, and include proposed geometry, operations, and warrant analyses for proposed signals, turn lanes, crosswalks, etc. and other analysis as appropriate.  Any proposed mitigation must be feasible.  Include proposed development requirements to accomplish the appropriate mitigation.
30. Copies of raw traffic count data used in the analysis (may be in an appendix).
31. Copies of the complete raw traffic analysis output showing the specific traffic data input, timing etc. used in the analysis, and specific results generated (may be in an appendix).
32. Copies of base electronic files (i.e. software files of queuing or capacity analysis) if requested to aid in staff review and allow for sensitivity analysis.
33. Any other information that the applicant’s team believes would provide a clearer picture of the proposed development and its anticipated impacts.
34. Any other analysis identified by staff as necessary and in the public interest to understand the proposed development and its anticipated and potential transportation impacts.

City staff may, at their discretion, add requirements as they judge appropriate to protect the public interest, or may waive one or more of the above requirements if the requirement is not applicable to the proposed development or would not provide enough information in the public interest to justify doing the analysis.