In order to improve the efficiency and safety on the freeway at the State Route 167 to northbound Interstate 405 interchange, newly installed ramp meters will turn on beginning Tuesday, July 27, 2021.
The Washington State Department of Transportation (WSDOT) will meter traffic during the peak morning commute from 6 a.m. to noon and intermittently during the afternoon in response to heavier traffic volumes and congestion.
This traffic change is part of an adaptive freeway metering system that automatically activates and adjusts each ramp meter based on current conditions.
Additionally, WSDOT traffic engineers can adjust the meter timing as needed to improve traffic flow.
Ramp meters are an effective tool used to operate state highways safely. More than half of the collisions over the past five years have occurred where SR 167 merges onto NB I-405.
- Ramp meters can improve safety by allowing one vehicle at a time to merge onto the interstate, reducing the severity and number of collisions due to merging traffic.
- Gaps between merging vehicles will make the merge easier for drivers and reduce the risk of collisions.
Efficiency of ramp meters
Vehicles entering the highway merge together in tightly packed groups, which can cause drivers on the mainline to slow down or even stop as they merge. This results in slower speeds, both on the freeway and on the ramp, quickly contributing to stop-and-go conditions.
- Ramp meters are designed to help evenly pace vehicles merging onto the freeway, providing consistent gaps between vehicles, rather than multiple vehicles flooding onto the highway at once.
- Ramp meters create a steadier flow of traffic onto the highway and reduces travel times.
- The SR 167 ramp meter can help alleviate and prevent free-flowing vehicles from hitting a dead-stop at the I-405 merge point.
- HOV and transit traffic will be able to use the I-405 Direct Connector that connects SR 167 to I-405 via the leftmost travel lane. With its completion in 2019, the Direct Connector siphons off traffic (HOV, transit, emergency vehicles) that would have been previously using the on-ramp.