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King County Road Services - Transportation Concurrency Management Program

About transportation concurrency

"Concurrency" was first required after Washington State passed the 1990 Growth Management Act or "GMA".externalink Concurrency as defined in state law means transportation facilities must be able to accommodate trips created by new development for the development to occur, “…local jurisdictions must adopt and enforce ordinances which prohibit development approval if the development causes the level of service on a locally owned transportation facility to decline below the standards adopted in the transportation element of the comprehensive plan…" (RCW 36.70A.070(6)(b)).

King County first implemented the Transportation Concurrency Management (TCM) Program by adopting its first Comprehensive Plan following the GMA in 1994, with TCM becoming effective in 1995. The program has undergone many changes since 1995 culminating with the most recent TCM changes being adopted by the King County Council on Oct. 6, 2008, as part of the 2008 King County Comprehensive Plan Update. The new TCM program changes became effective on Oct. 30, 2008. The transportation concurrency policies are found in Chapter 7, Transportation.

New concurrency regulations and level-of-service standards can be found in Title 14 of the King County Code. (579KB .pdf)

King County transportation concurrency was significantly changed in 2008. Key elements of the new program are summarized as follows:

  • Actual travel time is collected by corridor segments on County principal and minor arterials and certain State highways
  • Concurrency testing is by large geographic “Travel Sheds” where travel patterns share common characteristics
  • Concurrency testing evaluates travel time by roadway mileage within each travel shed
  • Rural mobility areas are identified, which are defined by land use, enhance multimodal travel, and reduce length of vehicle trips in rural areas
  • 85% of travel shed arterial mileage must meet concurrency standards
  • Residential and nonresidential proposals are tested by the same concurrency map
  • Concurrency is based on pass or fail of travel shed status on map; no certificate of transportation concurrency is issued
  • Clear identification is made of failing corridor segments that are the primary reason a travel shed is out of compliance
  • Increased transparency is created for projects needed to bring a travel shed back into compliance

Related information

Check your property's concurrency status

Check your property's transportation concurrency status using the King County Parcel Viewer. Input your property's address or 10-digit parcel identifier. After the application shows your property information, select "Districts Report" located on the lower left-hand side of the page. On the "Districts Report" refer to the row titled "Transportation Concurrency Management" for your "Pass" or "Fail" determination. Technicians at the Department of Development and Environmental Services (DDES) handling your application will check this on your pre-application form.

If your property fails concurrency

Should your property be identified as failing concurrency, check with a DDES staff member to see if your property or development proposal qualifies under the category “Minor Developments and Public and Educational Facilities,” which may allow you to proceed with your application (see King County Code 14.70.285). If the proposal does not meet these criteria, you cannot proceed with your development proposal until the property is identified as passing concurrency. You should check each year around October to see if the annual update of transportation concurrency has changed the status of your property.

Concurrency Annual Update

The Transportation Concurrency Management Program will collect travel time data on the county arterials in the spring of each year and test each travel shed for concurrency. The results will be adopted each year in the fall by the King County Council in the form of an updated Transportation Concurrency Map. Travel sheds passing today may fail the next concurrency update depending on the data collected. If a project development application is not complete, as defined by DDES as of the effective date of the new map, then concurrency passed today will not pass during the year the newly adopted map is in effect if the travel shed fails. The proposed development will not be allowed to proceed. Property owners and potential developers need to be aware of this possibility and allow enough time to complete their application before the concurrency update goes into effect.

For more information

For further information, please contact:

Jeff Lee, Transportation Planner
King County Department of Transportation
Road Services Division
201 S. Jackson St., MS KSC-TR-0317
Seattle, WA 98104-3856
Phone: 206-263-4759
Fax: 206-296-0566