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[Plutonic Panda]

I did read the entire article.

[Algorithm]

One quote from that article stuck out for me:

“If you think the backups at the First Avenue South Bridge are bad now, wait ‘til you see what it’s like when you basically are mainlining cars from I-5 to the west of Sea-Tac Airport straight to the First Avenue Bridge,” McGinn said.

Seems like this is a problem that can be mitigated by rechanneling southbound East Marginal Way traffic under the bridge, cutting a path through Front Street and a barely-used turnaround ramp. That would eliminate the light at the end of the bridge, and while there'd still be a light at 1st, I think this would provide a large improvement at minimal expense.

[jay8g]

Seems like this is a problem that can be mitigated by rechanneling southbound East Marginal Way traffic under the bridge, cutting a path through Front Street and a barely-used turnaround ramp. That would eliminate the light at the end of the bridge, and while there'd still be a light at 1st, I think this would provide a large improvement at minimal expense.

There's no such thing as "minimal expense" when buying new right-of-way in Seattle is involved, especially when railroads and industrial land are involved. Unless you're intending for it to be a 1-lane low-speed facility, which seems like it would defeat the point. Plus, I imagine there would still need to be a signal to merge the 3 lanes of northbound 99 with the three lanes of northwestbound East Marginal Way S.

I'm certainly never a huge fan of highway expansion, but I feel like these two projects aren't that big of a deal, basically just tying up some old loose ends, plus I imagine having these short links be tolled will mean that there won't be too much traffic using them. I sure hope WSDOT will make these the last major new freeways in the Seattle area, however.

[jakeroot]

I find McGinn's comment a bit puzzling anyway. The traffic at the First Avenue South Bridge is only bad because of the occasional bridge opening and, temporarily, diversion traffic from the West Seattle Bridge closure. Otherwise, I don't recall the bridge being a major pain-point for the 599/99/509 corridor(s).

When they dualled the bridge in the mid 1990s, I recall the project being a source of pride for local officials. 25 years later, there should still be plenty of pride: it handles way more traffic much more safely. They built the road to handle lots of cars, and it does so, even today, exceptionally well, even with all of the diversion traffic from the WSB -- what other intersection in Seattle has a quadruple left turn!? I don't think having 509 extend beyond 188th is going to be a major problem.

I get induced demand, but it's of secondary concern when you're talking about corridors so heavily used by freight traffic. Getting large trucks off local streets should be considered a major achievement for everyone. Trucks are slow, dangerous, and clog up the road; getting them onto corridors where they can operate independent of everything but other cars should be very important to everyone.

[Algorithm]

There's no such thing as "minimal expense" when buying new right-of-way in Seattle is involved, especially when railroads and industrial land are involved. Unless you're intending for it to be a 1-lane low-speed facility, which seems like it would defeat the point. Plus, I imagine there would still need to be a signal to merge the 3 lanes of northbound 99 with the three lanes of northwestbound East Marginal Way S.

I'm certainly never a huge fan of highway expansion, but I feel like these two projects aren't that big of a deal, basically just tying up some old loose ends, plus I imagine having these short links be tolled will mean that there won't be too much traffic using them. I sure hope WSDOT will make these the last major new freeways in the Seattle area, however.

There's enough room for two lanes between the railroad and the bridge ramp, and if you cut into the retaining wall under the bridge there should be enough room for a medium-speed curve.  No additional property acquisition required.  Also, East Marginal does not need three lanes going northbound.  I'm envisioning two lanes, merging to one before meeting 509, resulting in four northbound lanes with one splitting off onto 1st.  But even if there's too much traffic on East Marginal for one lane to handle, there's enough room for five northbound lanes in that spot since it'll all be one-way.

[jakeroot]

There's no such thing as "minimal expense" when buying new right-of-way in Seattle is involved, especially when railroads and industrial land are involved. Unless you're intending for it to be a 1-lane low-speed facility, which seems like it would defeat the point. Plus, I imagine there would still need to be a signal to merge the 3 lanes of northbound 99 with the three lanes of northwestbound East Marginal Way S.

I'm certainly never a huge fan of highway expansion, but I feel like these two projects aren't that big of a deal, basically just tying up some old loose ends, plus I imagine having these short links be tolled will mean that there won't be too much traffic using them. I sure hope WSDOT will make these the last major new freeways in the Seattle area, however.

There's enough room for two lanes between the railroad and the bridge ramp, and if you cut into the retaining wall under the bridge there should be enough room for a medium-speed curve.  No additional property acquisition required.  Also, East Marginal does not need three lanes going northbound.  I'm envisioning two lanes, merging to one before meeting 509, resulting in four northbound lanes with one splitting off onto 1st.  But even if there's too much traffic on East Marginal for one lane to handle, there's enough room for five northbound lanes in that spot since it'll all be one-way.

How does traffic coming off the bridge access 1st Ave?

[Algorithm]

How does traffic coming off the bridge access 1st Ave?

If there's only one lane coming from East Marginal, then the right lane on the bridge could access 1st without changing lanes.  On the combined northbound road, the rightmost lane would be right-turn only and the second-rightmost would be right-turn optional.  If there were two lanes from East Marginal, then they'd both go to 1st.  In this case, traffic could possibly cross-merge, but in the likely event that this would cause backups they'd have to stay separated and cross over on a side street like Lucille.  This is why I would prefer having only one lane from East Marginal at the merge point.

[KEK Inc.]

Or they can just turn 99 into a viaduct south of Spokane St. 

[The Ghostbuster]

I don't think the locals would be too pleased with that, even if the corridor is only populated by businesses and industries.

[TEG24601]

I don't think the locals would be too pleased with that, even if the corridor is only populated by businesses and industries.

It could just be a bypass.  Elevate a 2-lane passenger vehicle viaduct, for those headed over the Duwamish, and get that traffic off of the road and away from the trucks.  Might give them a chance to improve the surface conditions, and maybe give the road a diet, along with some new bike/ped facilities, and removing the disused rail infrastructure.

[jakeroot]

New visualisations of the 509 extension at 188th and 160th.

Slight change to the interchange design at 188th (1/4 partial cloverleaf with roundabouts) and some new roundabouts at the existing partial cloverleaf at 160th.

Warning for the cartographers: both visuals are south-up, confusingly.


SR 509 Completion Project Visualization: SR 509/South 160th Street Interchange by Washington State Dept of Transportation, on Flickr


SR 509 Completion Project Visualization: SR 509/South 188th Street Interchange by Washington State Dept of Transportation, on Flickr

[Plutonic Panda]

I’m surprised they’re only building SR-509 with two lanes each way.

[jakeroot]

I’m surprised they’re only building SR-509 with two lanes each way.

I don't think there's money for anything more than that.

I think the master plan calls for HOV ramps to 509 to/from the south on I-5, but not sure if that will ever happen.

[Bruce]

I’m surprised they’re only building SR-509 with two lanes each way.

It doesn't need to be any wider.

[jakeroot]

I’m surprised they’re only building SR-509 with two lanes each way.

It doesn't need to be any wider.

I would agree with that, especially given that 509 is only four lanes north of 188th.

That said, they were definitely thinking wider at one point (almost twenty years ago, I think). This may still happen once the South Access project at SeaTac Airport takes off:

[kkt]

Or they can just turn 99 into a viaduct south of Spokane St. 

 

[ErmineNotyours]

509 north of 518 is still dominated by galvanized steel with wood supports.  It's never been revised with an HOV lane and it looks like a time warp.  All the freeways in Puget Sound used to look like that.

[Bruce]

The clearest and simplest explanation of the SR 509 component I've seen yet.

[I94RoadRunner]

How about extending 167 over 512, and giving all this new freeway a new number?

In that case, we could extend WA 410 over the new freeway and all the way over to Downtown Tacoma on WA 509.

That's exactly what I was proposing in my post just above: end 167 at 410 or 512, and use 410 for the new route and eliminate 509 west of Alexander Ave in Fife.

Do not get rid of 512. I'm telling you guys that it's way too heavily used to be dumped and then moved a few miles to the north. It would be very confusing.

I don’t see any reason for the 509 designation between SR 99 at dash point sharing pavement up to SR 516 then sharing with 516 as well. I’d say truncate 509 at SR 99 at the Dash Point Rd intersection and then renumber the whole freeway north of there including the new extension as SR 517 as that is an unused number

[I94RoadRunner]

I don't think the locals would be too pleased with that, even if the corridor is only populated by businesses and industries.

It could just be a bypass.  Elevate a 2-lane passenger vehicle viaduct, for those headed over the Duwamish, and get that traffic off of the road and away from the trucks.  Might give them a chance to improve the surface conditions, and maybe give the road a diet, along with some new bike/ped facilities, and removing the disused rail infrastructure.

The original plans were for the Alaskan Way Viaduct to tie directly into the 1st Ave S Bridge as a full freeway. The section from the W Seattle Freeway to the 1st Ave S Bridge was never built however.

[jakeroot]

I don't think the locals would be too pleased with that, even if the corridor is only populated by businesses and industries.

It could just be a bypass.  Elevate a 2-lane passenger vehicle viaduct, for those headed over the Duwamish, and get that traffic off of the road and away from the trucks.  Might give them a chance to improve the surface conditions, and maybe give the road a diet, along with some new bike/ped facilities, and removing the disused rail infrastructure.

The original plans were for the Alaskan Way Viaduct to tie directly into the 1st Ave S Bridge as a full freeway. The section from the W Seattle Freeway to the 1st Ave S Bridge was never built however.

Welcome back to the forum!

Do you remember where you saw those original plans? I had never heard that. I'm guessing the plan would have been to replace the 1st Ave S Bridge whenever that southerly extension took place. And I doubt 509 would have ended prematurely in Burien if the freeway was continuous all the way into Seattle, as the demand for that route would have certainly been much higher without the (original) bottleneck at the 1st Ave S Bridge and an elevated freeway along East Marginal.

[I94RoadRunner]

I don't think the locals would be too pleased with that, even if the corridor is only populated by businesses and industries.

It could just be a bypass.  Elevate a 2-lane passenger vehicle viaduct, for those headed over the Duwamish, and get that traffic off of the road and away from the trucks.  Might give them a chance to improve the surface conditions, and maybe give the road a diet, along with some new bike/ped facilities, and removing the disused rail infrastructure.

The original plans were for the Alaskan Way Viaduct to tie directly into the 1st Ave S Bridge as a full freeway. The section from the W Seattle Freeway to the 1st Ave S Bridge was never built however.

Welcome back to the forum!

Do you remember where you saw those original plans? I had never heard that. I'm guessing the plan would have been to replace the 1st Ave S Bridge whenever that southerly extension took place. And I doubt 509 would have ended prematurely in Burien if the freeway was continuous all the way into Seattle, as the demand for that route would have certainly been much higher without the (original) bottleneck at the 1st Ave S Bridge and an elevated freeway along East Marginal.

I had seen it on an article about the RH Thompson freeway that was once proposed along Seattle’s eastern edge. In addition to the continuous freeway that was once proposed, there was a huge system interchange that was on the books for where SR 99 departed from SR 509 that was never built because the gap in the freeway never was built. The original interchange dud have direct ramps leading from SR 99/509 to Highland Park way but that was rebuilt to its current configuration in the mid to late 1990’s

[Bruce]

New flyover video from Sound Transit of the Federal Way Link Extension, which also includes footage of the SeaTac extension for SR 509:

[ErmineNotyours]

New flyover video from Sound Transit of the Federal Way Link Extension, which also includes footage of the SeaTac extension for SR 509:

At one time there was going to be an operations base at Midway at the location of the Dick's Hamburgers.  Now I don't see a break in the path anywhere for an operations base.

[Bruce]

New flyover video from Sound Transit of the Federal Way Link Extension, which also includes footage of the SeaTac extension for SR 509:

At one time there was going to be an operations base at Midway at the location of the Dick's Hamburgers.  Now I don't see a break in the path anywhere for an operations base.

Sound Transit's preferred site will be just north of SR 18. Since it won't be needed until the Tacoma Dome Extension is built, it doesn't need to be north of Federal Way TC.