Traffic Impact Analysis

What is a traffic report?

A traffic report, also known as a traffic impact analysis (TIA), is a study of the potential traffic impacts of a development on the surrounding transportation system. The purpose of the study is to document the impacts and recommend on-site and off-site mitigation for those impacts. 

When is a traffic report required?

A traffic report is required for any new development, re-development or change of use (including tenant improvements).

Who does the traffic report?

The applicant will hire a consultant to provide the traffic report. The consultant must be a professional engineer, licensed in the State of Washington.  

What is included in a traffic report?

There are two types of traffic reports:

Level-One Traffic Report

Level-One Traffic Reports are required for all new development, re-development or change of use projects. Some of the items to be included in the report are:

  1. Project Narrative
    • Existing and Proposed Use
    • Existing and Proposed Access Design
    • Existing Traffic Standard Nonconformities
  2. Trip Generation Data
    • Existing
    • Proposed Project Trips
    • Net New Trips
  3. Sight Distance for Vehicles and Pedestrians
  4. Other Information, as needed
  5. Recommendations
  6. Conclusions

Level-Two Traffic Report

Level-Two Traffic Reports are required for larger, more complex projects. Some of the items to be included in the report are:

  1. All Level-One Traffic Report Requirements as noted above
  2. Vicinity Map
  3. Discussion of internal circulation; may include a queuing analysis and loading plan with turning exhibits
  4. Concurrency
  5. Trip Distribution
  6. Level of Service
  7. Discussion of pedestrian, bicycle, and transit facilities
  8. Accident Report Data
  9. On-site and Off-site Mitigation
  10. Traffic Management Program


450 110th Ave NEP.O. Box 90012Bellevue, WA 98009

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