Median U-turns target traffic trouble in Federal Way

Federal Way is on track to be the first Northwest municipality to implement a street engineering design known as median U-turns.

The design is also commonly referred to as a Michigan left, as it originated in Michigan. A $3.36 million state grant will fund most of the approximately $4.5 million cost to construct a pilot project at the 21st Avenue Southwest and Southwest 336th Street/Southwest Campus Drive intersection.

If the design is successful, the city will look to spread median U-turns to other areas of Federal Way.

Innovative design

In all directions approaching a median U-turn intersection, lanes will be re-striped, essentially shifting everything one lane to the right. What are now left-hand turn lanes will become through lanes, and the existing far right-hand through lanes will become right-hand turn lanes.

Median U-turns are the most appealing solution to solving Federal Way’s traffic backups, given the city council’s 2010 instructions to staff to alleviate traffic, while avoiding lane widening, at 42 intersections expected to be operating at or above capacity by 2035.

“We were struggling very hard to come up with a cost-effective way to manage the traffic without massive intersection widening,” traffic engineer Rick Perez said. “This seemed like a good fit.”

Pilot project

Traffic engineers estimate the 21st Avenue and Southwest 336th Street intersection will see backups of at least one-quarter of a mile in all directions by 2035 if the roadway is left as is, Perez said. The intersection would be operating at 20 percent over capacity in this case, he said. Already, the crossing boasts a high collision rate.

Here’s an example of how the median U-turn design will work at the pilot location. A driver traveling east on Southwest 336th Street and wishing to turn left onto southbound 21st Avenue Southwest will travel through the intersection, then merge left into a newly created median U-turn lane. The driver will make a U-turn, with the assistance of a traffic signal, onto westbound Southwest 336th Street, and immediately begin merging to the right. Once reaching the intersection, for the second time, the driver will turn right to begin traveling southbound on 21st Avenue Southwest.

“We’re pushing the envelope a little bit here, but I’m confident it’s going to work,” Perez said.

At the Jan. 18 city council meeting where the grant was unanimously accepted by the council, some council members showed more enthusiasm toward the design than others. Councilwoman Jeanne Burbidge said she’s used median U-turns in Phoenix and found them comfortable to drive. Councilman Roger Freeman requested city staff make its best effort to educate the public on the matter, allow for safe U-turns and mediate the impacts to nearby businesses.

Design drawbacks

It will take time to educate the public on how to use median U-turns. The first step to driver safety will likely include public meetings before the design is completed, Perez said. Signage will be present. An educational website could be another tool, Perez said. Usually drivers catch on to the design within a year’s time, he said.

“The biggest disadvantage (to the design) is training drivers,” he said.

Despite its ability to move traffic, the design has the potential to negatively affect nearby businesses. Delivery trucks will use the design, making street widening necessary at the location where the U-turns take place, Perez said.

“We want to be able to accommodate truck deliveries to businesses,” he said.

The city is still contemplating whether to allow drivers to make left turns out of businesses located near the U-turns.

“There’s a couple different scenarios that could occur with how we treat access to those businesses,” Perez said. “I know the businesses are going to be concerned about access restrictions.”

Discarded options

Other options for addressing traffic conditions at the intersection were considered. Designs such as roundabouts and additional traffic lanes were in the running. A three-lane roundabout would be needed to adequately address traffic needs, Perez said. It would affect businesses on three of the intersections’ corners, bumping the price to build a roundabout up to nearly $12 million, he said.

“That drove up the cost tremendously,” he said.

Adding lanes was an undesirable option because it’s not considered pedestrian friendly and would likely require right-of-way acquisition.

“The biggest thing to remember is how we got here,” Perez said. “(City) council was very concerned about both the pedestrian impacts and the cost impacts of building massive intersections.”

Check it out

See a simulation of how median U-turns work by visiting

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