Traffic Q&A: Speed humps need city's OK, warning signs

Staff writerMarch 17, 2014 

Question: Does the city of Tacoma have a standard for speed bump authorization? In my West End neighborhood, I am noticing either a brand new or refurbished speed bump by the Highlands Golf Course, which has no signage for warning speeds.

With the speed limit at 25, taking the surprising speed bump at 22 mph is a back teeth-rattling jar to both jaw and suspension on my automobile. Can neighborhoods install their own speed bumps at punitive heights? — Jeff, Tacoma

Answer: The first thing to know is that, to traffic engineers, there’s a difference between "speed bumps" and "speed humps."

Speed bumps are the vicious little ones you find most often in parking lots. Speed humps are less aggressive because they rise more gradually. They’re the ones most often used on residential streets.

Under the city’s Neighborhood Traffic Calming Program, neighborhoods in Tacoma are allowed to install their own speed humps if the city approves and the humps meet specifications used by the Institute of Transportation Engineers and Manual on Uniform Traffic Control Devices.

According to city traffic engineer Joshua Diekmann, the city considers speed humps in places where studies show that most drivers are exceeding 33 mph on a residential street and where most residents support installing the humps.

“High demand and limited funding require Tacoma to prioritize the streets where traffic-calming measures such as speed humps will have the most benefit,” Diekmann said. “Speed humps are allowed to be privately funded and installed by a licensed and bonded contractor with proper city permits and neighborhood support.”

As for the speed hump near the golf course, Diekmann had it checked out and discovered that warning signs meeting city standards are not in place as they should be.

“The city will install appropriate signs next week,” Diekmann said Friday.

He added that if other readers notice a sign is missing or if they have questions about traffic calming in their neighborhood, they can contact the city’s transportation engineering division at 253-591-5500.

Rob Carson: 253-597-8693

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