Traffic Data & Speed Limits

Background


Public Works collects information on vehicle counts, travel speeds, and crashes in order to develop transportation projects that improve the safety and efficiency of our transportation system. The collection and analysis of data helps develop comprehensive transportation plans, such as the Six-Year Transportation Improvement Plan, helps maintain County roadway facilities, and enhances safety. Learn more by visiting the Washington Department of Transportation (WSDOT) website and the Maps and Data statewide information page.

Speed Limits


Jefferson County Code (JCC) 10.05.040 addresses speed limits on county roads. Pursuant to state law at RCW 46.61.400, the default speed limit on county roads is 50 miles per hour (mph). RCW 46.61.415 provides that local authorities may determine and declare a different maximum speed on the basis of an engineering and traffic investigation and a conclusion that the alternate speed is reasonable and safe under the specific road conditions.

Exhibit A of Jefferson County Ordinance 11-98 (amended through Ordinance 6-01) identifies specific speed limits on county roads. Amendments to Exhibit A are adopted by resolution of the Board of County Commissioners after review of an engineering and traffic investigation, public notification and a public hearing. For more information view JCC 10.05.040(3) and the Speed Limit Map.

Making Revisions


On November 19, 2018, the Board of County Commissioners adopted Resolution 59-18 with an updated Exhibit A, resulting in an adjustment to the speed limit on a singular county road.

Previous revisions occurred on July 15, 2013, when the Board of County Commissioners adopted Resolution 34-13 with an updated Exhibit A (2013), resulting in adjustments to the speed limit on select county roadways.

County Engineer's Analysis


Public Works prepares an Engineer's Report in conjunction with proposed changes to speed limits. The Report typically contains a description and analysis of the following elements:
  • 85th percentile speed
    85 out of 100 drivers are traveling at this speed or less
  • Crash history
  • Roadside development
  • Roadway characteristics
  • Cautionary speed on curves
  • Vehicle counts
  • Freight use
  • Land use zoning
  • Non-motorized use
The County Engineer makes a recommendation to revise the speed limits and requests the Board of County Commissioners to approve and adopt changes to Exhibit A, JCC 10.05.040(3).

For a recent example of this process, review the Shine Road Speed Report and its Appendices (October 2018).

Neighborhood Electric Vehicles (NEVs)


Neighborhood electric vehicles are speed-limited electric battery vehicles. In Washington state, NEVs are allowed on roads where the posted speed limit is 35 mph or less. For more information view the RCW 46.61.725 page.

Speed Bumps, Humps, Tables & Rumble Strips


Although we get a large number or requests, we do not install speed bumps, humps, tables or rumble strips on County roads due to their drawbacks and costs.