Seattle Sound Transit Light Rail Link

[pdxstreetcar]

why not route the eastside link through first hill via subway instead of the proposed I-90 alignment as it approaches downtown?

[PDXPaul]

$$$$$

[sequoias]

Hmmm, Lake Washington at the deepest point is about 900 feet deep. It wouldn't be possible to run a train under water to Bellevue. The only way is to run across the lake by bridge.

[BoulderGrad]

Originally Posted by sequoias

Hmmm, Lake Washington at the deepest point is about 900 feet deep. It wouldn't be possible to run a train under water to Bellevue. The only way is to run across the lake by bridge.

Actually, the very idea of running a tunnel under lake washington was discussed not too long ago. It might be uber more expensive than a bridge, but it is possible.

[CrazyAboutCities]

I'm curious when University Link starts construction this year? I noticed a several businesses on Broadway already moved to different locations along on Broadway. That area is the site where future light rail station will be built.

[citruspastels]

Originally Posted by BoulderGrad

Actually, the very idea of running a tunnel under lake washington was discussed not too long ago. It might be uber more expensive than a bridge, but it is possible.

I think it was more of a tunnel through lake washington wasn't it? Like a concrete tube actually in the water?

[pdxstreetcar]

i was thinking I-90 alignment for the bridge crossing but when it gets to seattle run in a subway under first hill. sure its expensive but its also a very dense and rather transit-oriented part of town and would allow the link line to serve a major area that would otherwise not be served by the link service. run east-west into downtown and end at elliott bay at the washington state ferry terminal, transfer to existing north-south route at pioneer square or university street station. i agree this would be very expensive though.

[BoulderGrad]

Originally Posted by pdxstreetcar

i was thinking I-90 alignment for the bridge crossing but when it gets to seattle run in a subway under first hill. sure its expensive but its also a very dense and rather transit-oriented part of town and would allow the link line to serve a major area that would otherwise not be served by the link service. run east-west into downtown and end at elliott bay at the washington state ferry terminal, transfer to existing north-south route at pioneer square or university street station. i agree this would be very expensive though.

As I recall, the original plan for the central link was to have an underground station under first hill, but that was abandoned because the soil is so poor that it would have required a very deep station.

[Capitol Hill]

The deep station, to the best of my knowledge, was because they were going to have to go quite a ways down to go under I-5, and then you have the rise of First/Capitol Hills.

[sequoias]

Originally Posted by BoulderGrad

Actually, the very idea of running a tunnel under lake washington was discussed not too long ago. It might be uber more expensive than a bridge, but it is possible.

I think I got the numbers from Puget Sound's depth. I researched again and Lake Washington deepest point which is northwest of Mercer Island is about 220 feet deep. It might be possible but too expensive for sure. It's easier to just build it on the bridge for sure. Transbay tunnel for S.F. BART at the deepest point is about 150 feet deep. The Bay Area is kind of shallow compared to Puget Sound region.

[UrbanBen]

Originally Posted by pdxstreetcar

i was thinking I-90 alignment for the bridge crossing but when it gets to seattle run in a subway under first hill. sure its expensive but its also a very dense and rather transit-oriented part of town and would allow the link line to serve a major area that would otherwise not be served by the link service. run east-west into downtown and end at elliott bay at the washington state ferry terminal, transfer to existing north-south route at pioneer square or university street station. i agree this would be very expensive though.

First, astronomically expensive. Second, we already HAVE a tunnel connection. Deal with first hill with a streetcar - you're talking about a billion dollar addition to a project for a piddly 5,000 daily riders.

[UrbanBen]

Originally Posted by BoulderGrad

Actually, the very idea of running a tunnel under lake washington was discussed not too long ago. It might be uber more expensive than a bridge, but it is possible.

It would be about as possible to simply build maglev between all our city cores. Get serious.

[BoulderGrad]

Happy Happy.

http://seattletimes.nwsource.com/htm...tmoney04m.html

[Bond James Bond]

^
Yay. Let's hope it doesn't get deleted out of the budget in congress.

[UrbanBen]

I think it's safe. Congress is generally more pro-FTA than Bush is.

[mokocoko]

Originally Posted by UrbanBen

I think it's safe. Congress is generally more pro-FTA than Bush is.

Check oiut the Four Car Link Trains
http://seatrans.blogspot.com/2008/02...ink-train.html

[sequoias]

Wow, it's really long!

[PDXPaul]

That's pretty cool, if you figure one of those probably carries around ~100 people, that's ~400 every few minutes. I know we could definitely use that in the UDistrict, there's lots of times on weekends and during rush hour that the 71/2/3 are filled to capacity but only with some 40ish people.

[UrbanBen]

Originally Posted by PDXPaul

That's pretty cool, if you figure one of those probably carries around ~100 people, that's ~400 every few minutes. I know we could definitely use that in the UDistrict, there's lots of times on weekends and during rush hour that the 71/2/3 are filled to capacity but only with some 40ish people.

Each of those carries 200 with 3 people per square meter standing, which is considered their "maximum" capacity. Much higher loads than that are possible - the 71/72/73 get more packed than that already. Japanese lines sometimes get as high as 10/sqm, to give you an idea of what's theoretically possible, but I'm sticking with 200 because it's comfortable. We'll probably see 250 per car at Stadium after games.

So you're talking about 800 people every 6 minutes, peak, with higher frequencies to come later.

[BoulderGrad]

Originally Posted by UrbanBen

So you're talking about 800 people every 6 minutes, peak, with higher frequencies to come later.

800 people/6 min = 8,000 people/hour

Figure 1 car/2 seconds at highway speeds ("safe following distance" given by most driving schools), any more it things start to slow down. thats 30 cars/min, which is 1,800 cars/hour.

So that means the train carries as many people/hour as 4.5 lanes of traffic. That bumps up to 6.6 lanes at 4 min headways.