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Traffic study results for Sunnyside Road/152nd Drive intersection call for daytime adjustment, changes go into effect Nov. 13

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As traffic increases, left turn gaps become harder to judge

The Clackamas County Traffic Safety Team in collaboration with the City of Happy Valley recently conducted a traffic study at the intersection of Sunnyside Road and 152nd Drive.  

County staff will attend the Happy Valley Traffic & Public Safety Committee meeting to answer questions about the traffic signal changes on Thursday, Nov. 14, 2019, 7 p.m. at City of Happy Valley City Hall, 16000 SE Misty Drive. The public is welcome to attend and provide comments.

During the study County staff observed traffic conditions, collected vehicle speeds, measured intersection visibility and researched recent crash data. Concerns were raised regarding the flashing yellow left turns for eastbound traffic on Sunnyside Road turning north onto 152nd Drive. 

With traffic growth in the City, a small increase in crashes for eastbound left turns from Sunnyside Road to 152nd Drive during the flashing yellow left turn sequence was documented. With higher traffic volumes, judging the gap to complete the left turn movement has become more difficult for drivers. 

To help prevent future crashes, the County will turn off the flashing yellow left turn sequence from 6:30 a.m. to 7 p.m. The option to turn left at this intersection from 7 p.m. to 6:30 a.m. will continue. Changes to the traffic signal will take effect on Nov 13th. 

In addition to reviewing Sunnyside at 152nd Drive, the County reviewed recent left turn crashes along Sunnyside Road with flashing yellow left turns including: SE 105th Avenue, SE 132nd Avenue, SE 142nd Avenue, SE 147th Avenue/SE Misty Drive, SE 157th Avenue, SE 162ndAvenue, and SE 169th Avenue. Higher traffic volumes at 162nd Avenue and 169th Avenue will also result in signal changes. Flashing yellow left turns at Sunnyside Road and 162nd Avenue will be permanently turned off; daytime flashing yellow left turns will be turned off during the day at Sunnyside Road and 169th Avenue.

The Clackamas County Traffic Safety Team is working to reduce injuries and fatalities on our roadways, with a goal of zero fatal and serious injury crashes by 2035. For more information, visit

Department Staff
Joe Marek
Traffic Safety
Cameron Ruen
Public & Government Affairs