Development Traffic Impact Review

All development projects in the City of Spokane Valley are subject to some level of traffic review. For small projects the review may be restricted to questions regarding location of access points. Larger projects often require a Traffic Impact Analysis (TIA) covering a larger area and/or Public Traffic Meetings.

When reviewing the traffic impacts of new development, the city follows the guidelines established by the Washington State Growth Management Act and the Washington State Department of Ecology Environmental Policy Act.

Traffic Impact Analysis

The City's standards for traffic impact analysis are outlined in Chapter 3 (PDF) of the Street Standards.

Traffic Engineering Abbreviations

  • ADT (Average Daily Traffic) - The amount of traffic traveling past a point during an average day.
  • AADT (Average Annual Daily Traffic) - Similar to ADT (above) except using the average day for the entire year.
  • AM Peak Hour - One morning hour having the highest traffic levels; normally during the 7 to 9 am period.
  • LOS (Level of Service) - A qualitative measurement of traffic flow that assigns an 'A' (best) to 'F' (worst) designation.
  • MUTCD (Manual On Uniform Traffic Control Devices) - A federal publication governing design and placement of all traffic controls (signs, signals, and pavement markings). The State of Washington has adopted the 2009 MUTCD with select modifications.
  • PE (Professional Engineer) - A state of Washington registered Engineer.
  • PM Peak Hour - One afternoon hour having the highest traffic levels, normally during the 4 to 6 pm period.
  • TIA (Traffic Impact Analysis) - A study of the potential traffic impacts of a development on the adjacent transportation systems.
  • Trip Generation - The amount of traffic coming from and going to a development.
  • TWLTL (Two-Way Left Turn Lane) - Center lane allowing left turns from both directions.
  • VPH (Vehicles Per Hour) - The number of vehicles passing a point in one hour.