Representatives from Thurston County Public Works proposed lower speed limits for seven roads and a higher speed limit for one route, to the Board of County Commissioners (BoCC) yesterday, September 20.
Public Works Traffic Engineering & Operations Manager Becky Conn stated that the county adopted national and state laws to set the county speed limits.
Conn mentioned that the county adopts the Manual of Uniform Traffic Control Devices (MUTCD), the national standard for all public roads, and the state legislation.
“At the state level, we have RCW 46.61.415, which states that local agencies may establish limits between 20 and 60 miles per hour on their local roadways,” Conn said.
At the county level, the Thurston County Code (TCC) 12.105 is adopted, which states that all of the speed limits on Thurston County roadways will be 50 miles per hour unless established otherwise.
“If they are established otherwise, they will be designated in the Thurston County speed limits schedule. And that's the document that gets revised each year when we make revisions,” Conn said.
Conn also mentioned Thurston County Resolution No. 16142, which helps outline the Engineering Study processes and guides how to set speed limits.
“The speed limit we set should be within 10 miles per hour of the 85th percentile speed. That is the speed that 85 out of 100 vehicles are traveling at that speed or below on the given runway,” reported Conn. “You don't want to set the speed limit below the lower limit of the 10-mile per hour pace speed.”
“The speed limit revision process that we follow here, the county, starts with receiving a request. We get a lot of requests from citizens, we get requests through the commissioner's offices,” Conn shared.
The office also receives requests internally (from the Public Works design team) and the sheriff's office.
“Once we receive the requests, we conduct an engineering study. We do a traffic count on the road,” said Conn. “We're getting the speed that the vehicles are traveling, which helps us get that 85th percentile speed. We see how many vehicles are traveling out there. We can get what types of vehicles-- are there buses, are there passenger cars? Are there a lot of trucks? It gives us all those kinds of numbers.”
The data gathering, which also recommends lowering or raising speed limits, is part of the engineering study, to be followed by an informal public comment.
“At that point, we do a little informal public comment-- we contact the people along that roadway to see their thoughts and get their input on that change,” said Conn.
From there, public works will take all the data from the request, engineering study, and public comment and propose a new speed limit.
Conn also reported the specific changes to each route.
Only the Union Mills route got a proposed increase in its limit because the posted speed is not consistent with the county’s speed limit schedule.
The next step for the BoCC is to set and hold a public hearing to consider the proposed revised speed limits.