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.