|We plan to open a new peak use shoulder lane on this|
section of northbound I-405 by summer 2017.
We have both short-term and long-term plans to add new roadway capacity that will help smooth out these trouble spots. Today we have some good news to share: we’re moving forward with our first set of improvements even sooner than expected!
Originally, the Legislature funded this project with an expected opening date in 2018. However, thanks to higher than expected revenues from the I-405 express toll lanes and some changes to the project scope, we are now able to fund and get started on this project even sooner than expected. That’s right: I-405 toll revenues are already being reinvested into the corridor.
So what’s happening?
Next summer we plan to open new northbound capacity, called a peak use shoulder lane, which will extend about 1.8 miles between SR 527 and I-5 (you may have also heard it referred to as hard shoulder running). As the name suggests, we plan to make some roadway changes that allow us to open the right shoulder to general purpose traffic during times with heavy traffic.
By building more capacity to handle the afternoon traffic entering from SR 527, we expect to clear out much of the congestion that travelers are experiencing, especially in the area of the SR 522 interchange, where I-405 narrows from five lanes to three lanes.
It’s worth noting, of course, that we can’t erase all congestion. Because vehicles will be able to travel north more quickly, we expect to see some more back-ups at the I-5/I-405 interchange as drivers reach northbound I-5 and its heavy congestion.
How will the peak use shoulder lane work?
Dynamic lane control signs, much like the ones you see today on I-5, I-90, and SR 520, will let people know when the peak use shoulder lane is open to traffic. In general, the lane will be open during the afternoon peak period (3 to 7 p.m.), when drivers need it most, but it will also be available to help manage the highway for incidents or other unexpected congestion that can occur.
We also recognize that the shoulder will still be needed for maintenance, emergency services, and vehicle breakdowns. Dynamic lane control signs like the one in the picture below will help us manage those uses, so it’ll be very important for drivers to pay attention to those messages. We’ll have a lot more to share about how to use the new peak use shoulder as this project moves forward.
|Signs like this one will help control traffic on the new I-405 peak use shoulder lane.|
Why is there so much congestion up north anyway?
When we completed improvements on I-405 last September, we only had funding to build a new lane between Northeast Sixth Street in Bellevue and south of the SR 522 interchange in Bothell. North of SR 522, we left the amount of lane capacity unchanged.
Before we added the new lane from Bellevue to Bothell, northbound traffic used to get stuck farther south in the Kirkland area during afternoon rush hour. Since we added the new lane and launched express toll lanes, we’re moving more vehicles through this area faster. On average, somewhere between 17 and 24 percent higher volumes during the peak commute than before express toll lanes, according to our nine-month data.
But when this much larger wave of cars reaches Bothell, where the road narrows, they hit a bottleneck causing significant congestion. Add to that the busy SR 527 interchange, where nearly 1,000 cars an hour are merging into those full northbound I-405 lanes during afternoon rush hour, and we see big backups. To be fair, with the growth in the area over the past few years, this section of roadway didn’t have enough capacity to handle all the cars that need to pass through even before express toll lanes.
What else are you going to do?
We know we aren’t finished making improvements yet. The long-term I-405 Corridor Master Plan ultimately calls for rebuilding the SR 522 interchange and adding more lanes which will create a dual express toll lane system that extends north to I-5.
The Legislature asked us earlier this year to seek new ways to phase this big project so that we can reduce its cost and build critical pieces sooner, and that’s exactly what we’re doing right now. Stay tuned for more information on our progress.
How can I learn more about these upcoming projects?
WSDOT plans to host an open house about this new peak use shoulder project 5 to 7 p.m. Thursday, Aug. 18 at Bothell City Hall Council Chambers. It is open to the public, and we look forward to seeing you there.