It’s one of the busiest series of ramps along I-5, and also one of the last to get ramp meters to help ease congestion. Now, major changes are coming for how drivers get on the freeway at Mercer.
The Mercer on-ramps to I-5 are some of the biggest chokepoints in the region. The relentless stream of cars needing to merge onto the freeway causes I-5 to backup daily. The state is finally going to do something about it by installing ramp meters to help break-up the constant flow of cars.
“We’ll let one car go at a time, and as they merge onto the freeway they will have space to merge more safely and more efficiently,” Washington State Department of Transportation Traffic Engineer Morgan Balogh said.
In the northbound direction, the state will install two ramp meters before the exit for the express lanes. Those ramp meters will likely only be in use in the morning when the express lane exit is closed. The southbound on-ramp from Mercer is a little different. The state is going to use the shoulder to add room for more queuing, allowing room for three ramp meters.
“We have two lanes now, so we’re going to take the shoulder and add a third lane that will be operating when the meter is running,” Balogh said. “We’ll have more storage, and we’ll be able to have more flexibility in how we release the traffic.”
The overall impact for I-5 should be significant.
“We should see the number of crashes go down about a third, and we should see the volume through the area go up maybe three to five percent,” Balogh said.
Now, I know what you’re thinking. The state is going to slow down access to I-5 from Mercer when it’s already backed up every day? Why would the state do something that will make Mercer even worse?
Balogh and the Seattle Department of Transportation said this change should not impact the current situation on Mercer. It’s not going to be any better or worse because conditions on Mercer are already beyond bad.
“It backs up now,” Balogh said. “We’re going to let the same number of vehicles go through in the future as we do now, so there shouldn’t be any difference or any additional impacts.”
We’ll see. The ramp meters will go active on the weekends for about a month, beginning March 10, before going live in April.