Question: Reader Joanie Dobesh of Spanaway wants to know how Pierce County determines speed limits. “In the Parkland/Spanaway area, there are some residential streets that are 25 mph, some are 30 mph, some are 35 mph and some are 40 mph,” she wrote. “There doesn’t seem to be any rhyme or reason to the different limits.”

Answer: James Ellison, the county traffic engineer, said the basic speed limit for Pierce County roads, including all local neighborhood roads, is 25 mph. Speed limits that differ from that are adopted through an ordinance of the County Council based on a traffic engineering study.

“The county roads that have speed limits above 25 mph are all arterials,” Ellison said. “Each arterial classification has a typical range of speed limits that is assigned on an individual basis. Major arterials, such as Canyon Road or 112th Street East, for example, tend to have a higher range of speed, while collector arterials like A Street South have a lower range of speed.”

Ellison said several factors are considered when determining the actual speed limit on a particular road. “These involve the speed at or below which 85 percent of the drivers are traveling; the roadway characteristics including curves, grade, sight distance; the influence of driveways, side streets, and adjacent land uses along the road; and other safety considerations,” he said.

For more information on speed limits, visit the county’s Web site: www.piercecountywa.org/traffic.

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