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Speed Investigations Basics

We conduct engineering investigations in order to establish speed limits that differ from those set in state statute. The resulting speed limits are known as designated speeds.

We establish designated speeds when statutory speeds may not be reasonable or applicable. ODOT has primary authority to establish designated speed zones on public roadways, Oregon Revised Statute 810.180. It directs ODOT to use the process described in Oregon Administrative Rules and requires an engineering investigation when establishing designated speeds on public roadways.

These engineering investigation and resulting reports are required for both state highway and local agency roadways. ODOT has traditionally completed these investigations as a courtesy for local agencies upon request made by the local agency. Although typically completed by ODOT, local agencies are also able to complete the investigation and submit the report to the state traffic roadway engineer's office for review and approval.

State statute also allows ODOT to delegate its speed zoning authority to cities and select counties. Learn more about ODOT's delegated authority parameters and process.

Engineers base their investigation on national standards, in addition to requirements called out in Oregon law. The investigation includes a full review of roadway characteristics. These attributes include, but are not limited to:

  • Context to the roadway, as defined in OARs.
  • Federal functional classification.
  • Crash history.
  • Roadside culture and density.
  • Traffic volumes.
  • Roadway alignment, width and surface.
  • Motor vehicle speeds.​​

When ODOT engineers complete their investigation, they prepare a report and recommendation, providing it to ODOT's state traffic roadway engineer and the local road authority​ for review.

  • If the city or county agrees with the recommendation, the new speed zone is established.
  • If ODOT and the local road authority do not agree, we refer the request to the Speed Zone Review Panel. The panel hears ODOT's recommendations and testimony from the local road authority and makes the final decision.

The panel includes representatives of the Oregon Transportation Safety Committee, Oregon State Police, the Association of Oregon Counties, the League of Oregon Cities, and ODOT.​

OARs for Non-Interstate Speed Zoning

Investigation Data and Templates

Contact the Traffic Section

4040 Fairview Industrial Drive SE, MS5
Salem, Oregon 97302
Phone: 503-986-3568
Fax: 503-986-3749

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