Thursday, February 8, 2018

Traffic signal ahead: Mercer Street ramp metering begins March 10

By Lisa Van Cise

Call it a clog, a slow-down, a standstill or some other colorful phrase, merging onto I-5 from Mercer Street in Seattle can be a trying experience, with backups extending beyond the length of the on-ramp to I-5. Also exasperating- the I-5 drive through Seattle as the onslaught of slow-merging vehicles brings freeway traffic to a halt.

Beginning Saturday, March 10, the merge will look a little different. New signals installed on the ramps from Mercer Street to both northbound and southbound I-5 will help to pace the merging vehicles. For the first month, the signals will meter traffic during the weekends. After a month of monitoring and evaluating the metered traffic, our engineers will turn on the signals during the week as well. Weekday metering will start as early as April 10.

Take a peek at this animation to get a feel of how the new configuration will work:
How the Mercer ramp meters will work
On Mercer Street, once you cross Fairview Avenue, you will have two lanes on the ramp to northbound I-5 and three lanes on the ramp to southbound I-5 where you can wait for your green light to merge onto the freeway. The signals will alternate traffic from each lane, and instead of a clogged ramp, picture more of a slow leak of vehicles onto I-5. Gaps between merging vehicles will make the merge easier and reduce the risk of collisions near the I-5 on-ramps.

Traffic engineers will monitor congestion and travel times on I-5 to determine when to turn on ramp metering. In coordination with the Seattle Department of Transportation, they will also monitor and adjust the ramp metering when it is active. As far as backups and delays on Mercer Street itself, engineers do not expect any negative effect.
Drivers waiting on the Mercer Street on-ramps to northbound and southbound I-5

Benefits of ramp metering
Many of us can feel a bit stressed looking ahead to merging traffic. Whether merging lanes or merging from the on-ramp to the freeway, predicting fellow driver behavior can be taxing. The new signals will help to ease some of the anxiety by alternating traffic and taking out the guesswork. Ramp meters also typically:
  • Create steadier flow of traffic onto the freeway
  • Reduce freeway travel times
  • Reduce the severity and number of collisions due to merging traffic
For more information about ramp meters, check out our ramp meter webpage.

We are confident the new meters at this major downtown intersection will help move traffic out of the city safely and with more consistency.


Sean Ell said...

This is ridiculous, I'm on the S-bound on-ramp to I-5 every weekday afternoon and this is just going to screw things up. You say it'll cut down on collisions -- I've never even SEEN seen a collision on the on-ramp -- and "take out the guesswork" of merging, AND make merging onto I-5 "smoother." Good god, how much "guesswork" is there??? I've often thought you could simply spend just $500 on some "Zipper Merge" signs and it would help the clueless people, even though most people already get it and it usually goes just fine. But no, you have to spend, I'm sure, tens of thousands of dollars to install (and monitor, and program) THREE new lane-merging signals.

I KNOW what's going to happen: the signals will end up allowing WAY too much time between cars, so it will back traffic up onto Mercer even more. As it is, people slowly zipper merge with each other and there's probably ONE second between each of us, because we're steadily going 4-5 MPH but always moving. The signals will stupidly put 3-4-5 seconds between each car, stopping traffic behind it, and it'll be a hell of a backup.

As far as your claim about making merging onto I-5 smoother, that's absurd -- by the time we're merging onto I-5, we've gone almost half a mile, and by then, people will be spaced close together, just as they do now. That's a really long merging lane.

I could be wrong -- but I doubt it. Couldn't you try putting-in a few FAR less-expensive "zipper merege" signs first?

D.P. said...

There are sooo many simple and cheap things that Seattle could do to help traffic, but they actively choose to do whatever possible to make commutes, and private vehicle travel as absolutely as long, slow, dangerous and painful as possible.
This is 100% planned and executed by this poor excuse for city management, and the false claim of being 'progressive'.
The reality is purposeful and planned: making driving a car SUCH a bad experience that people will be forced to try to use our horrific mass transit.

I drive southbound through downtown every morning... 75% of the vehicles getting on I5 at Mercer are getting off at the next exit (4 or 5 lanes to the right). Why in earth is this allowed?
Why is access to the express lanes so limited. North into seattle in the evening, the main line can be backed up for miles, but almost no one is in, or can get into the express lanes.

Seattle city management is completely incompetent in SOOO many regards....this is just another example.

Texting while problem
Blocking an problem
Choking down main roads and having busses stop IN the traffic problem
Allowing uber/Lyft to stop in the middle of the problem
Camping in the left lane, forcing car after car to go around on the problem
Light timing completely opposite of any logic, or any intent of keeping traffic problem
Driving with no lights on I5 at problem
Stopping in I5,Just as you approach downtown from the south to take pictures from your problem

Teddy said...

This is yet another example of someone at WSDOT (and SDOT) with a "vision" for how they think things *should* go and not how they *actually* go.

Here's an idea; why don't you ask we, the commuters who are stuck in your poorly-designed, massively under-engineered mess on what are the biggest problems we see every single day crawling through this slog? You might just find out a lot more information than your fancy multi-million dollar "2-second saving" 'algorithms' and computer simulations spit out.

Do you want traffic to back up past KeyArena on Mercer? Because you're going to get it. Do you want Denny to be even more of a disaster than it already is? Because you're going to get that too. The Mercer ramp is already so overcrowded it backs traffic up for miles, and yet your solution is to 'slow it down even further'; the logic is just not there. Why don't you instead move the useless express lane to start after the downtown tunnels, so you don't have 10 feet to get out of the left lane before they start? Why don't you have traffic police manually controlling the flow of traffic on Mercer or Denny so people don't block intersections and completely clog the flow of traffic? Why don't you temporarily close some side streets and alleys during certain times of the commute so the main arteries actually flow? Why don't you look at how the traffic backs up from Union St. spilling all the way down I-5 to the Yale entrance to the highway, thereby massively slowing the amount of cars that can actually merge onto I5 from Yale? Why aren't we regulating the ride-share flunkies from holding up traffic by picking up fares in the middle of moving traffic? The list goes on and on. This isn't just a WSDOT issue.

Instead of heavy-handed, draconian moves like this one completely out of the blue, how about you seek more. public. input? Ask us what challenges we face; I live 12 miles from my work near the Space Needle and I spend 3-4 hours in the car every day. (And no, the bus would be longer.) This move isn't going to do anything but cause the so-called "accidents" (I have never seen one on this stretch in the 3.5 years I've worked downtown) to shift onto city streets instead. And what does that solve?

Vu Nguyen said...

You can't be serious WSDOT

a said...

I'm glad we are spreading out the Mercer mess when entering the highway so that a solid wall of cars are not trying to cross every lane of traffic in a short distance to travel to the suburbs. This won't fix the Mercer mess, but it will at least not make the rest of he highway grind to a halt as much at this choke-point.

MoiAussi said...

The impact to drivers leaving the South Lake Union area after 3:30pm M-F will be detrimental. I turn right from Fairview Ave N onto Mercer to enter the I-5 North ramp and it's already a gong show with the backlog of cars waiting to get onto I-5 S. This will worsen congestion on the side streets feeding into Mercer (such as Fairview, Eastlake)and will make Mercer street a larger parking lot at rush hour. SDOT and WSDOT projections that this will not impact city traffic is difficult to believe. I wonder if the SDOT and WSDOT employees actually tried to navigate this area before deciding to implement this idea?

Ready to GTFO of Seattle said...

Another STUPID idea from the City of Seattle. These metered ramps create more backups on the ramp itself, which backs up the streets leading to the ramps. Another reason why living in Seattle is becoming less desirable. Pure stupidity!!!!!

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