What is a Traffic Impact Study?
A Traffic Impact Study (TIS) may be required to demonstrate the applicable land use review approval criteria are met. A TIS may also be needed to address operational or safety issues. Please note that many intersections in the City have limited capacity and may not be able to accommodate area growth plus the proposed land use without mitigation. Under some circumstances, lack of adequate capacity (level-of-service) at an intersection can result in denial of a land use proposal. Intersections of higher classified streets are most likely to have capacity constraints but other intersections may as well. The applicant’s traffic engineer should investigate this issue well in advance of application for the land use review. Please see TRN 10.27- Traffic Capacity Analysis for Land Use Review Cases.
The Traffic Impact Study (TIS) must be prepared by an Oregon licensed traffic engineer. Traffic Impact Studies are complex and almost always require multiple engineering reviews to ensure that all issues are fully addressed in a technically acceptable manner. Please allow for adequate time in your project timeline. The more complex the situation, the longer the review is likely to take. Plan on a minimum of 4 weeks for the initial review. Additional time may be needed for revisions or additional data collection.
The scope of work for the required Traffic Impact Study must be approved by PBOT prior to preparation of the study. This is intended to avoid a situation where an applicant must pay to gather data more than one time. The applicant’s traffic engineer must propose a draft scope of work via the scope approval forms available below.
Completed Scope Approval forms and any supporting documentation are to be emailed to PBOT at PBOTDevRevTrafficScopes@portlandoregon.gov. Review of scoping documents generally takes 3 weeks, though this can vary. Please direct additional questions regarding the required TIS or the Scope Approval Forms to PBOTDevRevTrafficScopes@portlandoregon.gov.
Timeline for land use or building permit reviews
TIS are complex technical documents that take time to review and often require ongoing coordination between PBOT and the applicant’s traffic engineer. Plan on a minimum of 7 weeks for the initial review. Additional time may be needed for revisions or additional data collection. The more complex the situation, the longer the review is likely to take.
For a project with a land use decision prior to building permit:
Step 1: Prior to the land use application being deemed complete, submit the scoping forms. Allow at least 3 weeks for review. PBOT will not consider the application complete until the scope is approved and the completed traffic study is submitted.
Step 2: Submit the traffic study for review. Please allow at least 4 weeks for review, with additional time for revisions if necessary. PBOT will not support a land use application that requires a TIS without the TIS being approved by a PBOT Development Review Traffic Engineer.
For a project without a land use decision prior to building permit:
Step 1: Prior to building permit submittal, submit the scoping forms. Allow at least 3 weeks for review. PBOT will not consider the application complete until the scope is approved and the completed traffic study is submitted.
Step 2: Submit the traffic study for review. Please allow at least 4 weeks for review, with additional time for revisions if necessary. PBOT will not approve a building permit that requires a TIS without the TIS being approved by a PBOT Development Review Traffic Engineer.
Scope Approval Forms
The “Traffic Scope Approval Form” and "Traffic Impact Study Parameters Form" should always be completed for every TIS. The other scoping form or forms may or may not be appropriate based on the project.
Prior to starting any of the following traffic study, a Traffic Scope Approval Form must be completely filled out, submitted for review, and approved by PBOT’s Development Review Traffic Engineer. The Traffic Scope Approval Form shall be included in every traffic study submittal as Attachment A. PBOT may require additional analysis/information during the course of the review of the project. This Traffic Scope Approval Form is for City requirements only. Consultants must contact ODOT to determine requirements related to access permits and work in ODOT right-of-way. For more information on ODOT requirements, please visit the ODOT Access Management Page.
This traffic study parameters attachment must be completely filled out and submitted for review along with the Traffic Impact Study Scope Approval Form.
One or more of the forms below may also be needed depending on the scope of the project.
The Parking Impact Study form should be filled out if your project must study parking impacts. Examples of projects this form applies to include:
-seeking an adjustment to the minimum or maximum number of vehicle parking spaces allowed by the zoning code
-to establish the amount of parking required for a conditional use.
The Loading Demand Study form should be filled out if your project includes an adjustment or modification to the loading requirements of the zoning code.
The Accessory Short Term Rental Traffic and Parking Study form should be filled out if you are seeking a conditional use review for an Accessory Short Term Rental.
Transportation and Parking Demand Management Plan Scoping From should be completed for any land use review triggering the requirement for Transportation and Parking Demand Management. This can be required in the Campus Institution Zones and for developments of more than 10 units in the Commercial/Mixed Use or Residential Multi-family zones or if seeking to use TDM as mitigation for a complex project.
Guidance Memo for Traffic Count & Speed, Data Collection and Analysis During Pandemic
With Multnomah County entering Phase 1 of the state's reopening plan and traffic volumes on the rise, PBOT is providing guidance for consultants, developers and staff that need traffic counts for traffic impact studies or project scoping. PBOT has been collecting traffic volume and speed counts at multiple locations across the City during the pandemic which will help determine the need for adjustment factors at particular locations.