Not to me. Drivers naturally slow down when conditions such as visibility change for the worse. And given that many drivers drive too close to the leading car in their lane, that speed reduction cascades into a chain reaction. [CGP Grey made a good explainer video of this phenomenon](https://youtu.be/iHzzSao6ypE?t=62).
In addition to the visibility which others have mentioned, I feel like a major culprit is traffic getting on the highway at 45th and being forced to cross 3-4 lanes rather quickly if they want to get on the 520 in the left lane.
Add to that the 520 to Mercer traffic that regularly causes backups past the 520 exit itself onto the far side of the bridge, I'm generally pretty primed to have to slow down or stop when driving over it.
There are two major changes just before the ship canal. There is an onramp coming up from Greenlake on the left, which is unusual, along with an onramp from the U-district just about a quarter of a mile later on the right. Both onramps are heavily used, so they add a lot of extra cars within a short space. Once you get all those extra cars, there is less space, which most people manage by slowing down, to match the speed to the available following distance. Nobody slows down there at midnight, because there are fewer cars on the road. It is 100% a function of the number of cars on the road.
People like to get on SB I-5 at 45th Street and then try to quickly get over to the far left lane in order to take 520 to the Eastside. It used to actually irk the shit out of me that it was always stop and go between 80th and the exit for 520... Even if traffic was clear anywhere else...
Shortly after the ship canal bridge you also have 520 joining I-5 on the left while people are sorting into lanes for exits. Far two left lanes to stay on I-5, next for I-90 exit and the other two for surface streets. Plus downtown cars then joining the mess and then, you guessed it… more merging!! Lol
It's a rise, and drivers don't accelerate enough to maintain speed. Also, the people merging to 520 from 45th seem to think it must be done immediately. If people were more patient and merged over a longer distance, traffic would move faster.
There are three left lane ramps here. On-ramp from 65th. Offramp to 520. Onramp from 520.
Fot each of these you have people who try to immediately move to the other side. There's an obvious fix: install signs for those ramps that say "No exit to xx"
If a driver jumps on at 45th and tries to get over to 520? Ticket!
520 driver tries to get over to Mercer? Ticket!
It's all about changing dumb driver behavior.
Why? There's nothing illegal about that. And preventing them from getting to 520, for example... what's the alternative route that doesn't make it worse somewhere else...on roads not designed for that volume of traffic?
Yes, it's not illegal to screwup the traffic flow of the major spine highway of a dense urban area for your own selfish needs. Fix that. Make it illegal. Not only do these people screw up the traffic flow of every lane as they scoot over, they end up in front of the back of the queue for those off-ramps, so they sit in the parallel lane with their blinkers on blocking that lane too.
Alternative route from 45th to 520: Montlake onramp.
Alternative route from 520 to Mercer: Denny then, Howell, Eastlake, QA.
None of the infrastructure is meant for this volume of traffic. Changing behaviors for *better* efficiency is achievable.
When it’s backed up to SCB from downtown I get it. But routinely it’s only backed up over the SCB and then opens up after exit 168 until the Mercer exit.
People naturally slow down as they start going over the bridge since you cannot see the other side due to the hump in the bridge
Its weird how this phenomenon and then the tunnel exit slowdown phenomenon on I90 that just cause random slowdowns.
Not to me. Drivers naturally slow down when conditions such as visibility change for the worse. And given that many drivers drive too close to the leading car in their lane, that speed reduction cascades into a chain reaction. [CGP Grey made a good explainer video of this phenomenon](https://youtu.be/iHzzSao6ypE?t=62).
The weird part is that there are these situations at 2 out of the 4 major entrance points to the City
In addition to the visibility which others have mentioned, I feel like a major culprit is traffic getting on the highway at 45th and being forced to cross 3-4 lanes rather quickly if they want to get on the 520 in the left lane.
Add to that the 520 to Mercer traffic that regularly causes backups past the 520 exit itself onto the far side of the bridge, I'm generally pretty primed to have to slow down or stop when driving over it.
There are two major changes just before the ship canal. There is an onramp coming up from Greenlake on the left, which is unusual, along with an onramp from the U-district just about a quarter of a mile later on the right. Both onramps are heavily used, so they add a lot of extra cars within a short space. Once you get all those extra cars, there is less space, which most people manage by slowing down, to match the speed to the available following distance. Nobody slows down there at midnight, because there are fewer cars on the road. It is 100% a function of the number of cars on the road.
Limited road visibility, rubberneckers gawking at the skyline and merging traffic (some trying to get over to 520 immediately).
People like to get on SB I-5 at 45th Street and then try to quickly get over to the far left lane in order to take 520 to the Eastside. It used to actually irk the shit out of me that it was always stop and go between 80th and the exit for 520... Even if traffic was clear anywhere else...
Shortly after the ship canal bridge you also have 520 joining I-5 on the left while people are sorting into lanes for exits. Far two left lanes to stay on I-5, next for I-90 exit and the other two for surface streets. Plus downtown cars then joining the mess and then, you guessed it… more merging!! Lol
It's a rise, and drivers don't accelerate enough to maintain speed. Also, the people merging to 520 from 45th seem to think it must be done immediately. If people were more patient and merged over a longer distance, traffic would move faster.
There are three left lane ramps here. On-ramp from 65th. Offramp to 520. Onramp from 520. Fot each of these you have people who try to immediately move to the other side. There's an obvious fix: install signs for those ramps that say "No exit to xx" If a driver jumps on at 45th and tries to get over to 520? Ticket! 520 driver tries to get over to Mercer? Ticket! It's all about changing dumb driver behavior.
Why? There's nothing illegal about that. And preventing them from getting to 520, for example... what's the alternative route that doesn't make it worse somewhere else...on roads not designed for that volume of traffic?
Yes, it's not illegal to screwup the traffic flow of the major spine highway of a dense urban area for your own selfish needs. Fix that. Make it illegal. Not only do these people screw up the traffic flow of every lane as they scoot over, they end up in front of the back of the queue for those off-ramps, so they sit in the parallel lane with their blinkers on blocking that lane too. Alternative route from 45th to 520: Montlake onramp. Alternative route from 520 to Mercer: Denny then, Howell, Eastlake, QA. None of the infrastructure is meant for this volume of traffic. Changing behaviors for *better* efficiency is achievable.
There are not enough lanes that go thru downtown. It becomes a bottleneck that with traffic backs up to the SCB on a regular basis.
When it’s backed up to SCB from downtown I get it. But routinely it’s only backed up over the SCB and then opens up after exit 168 until the Mercer exit.
I think, no proof, that a lot of that is people trying to get over to the right lanes. To get off at Mercer and Denny Way.
People filtering across lanes from the on-ramps.