According to Mai Ling of Maple Leaf Life, Sound Transit unveiled an alternative to the North Link light rail line extension at the recent public meeting at Roosevelt High School:
University Link Deputy Project Director Ron Endlich introduced a new proposal to keep the light rail line underneath Interstate 5 farther than the current proposal, which has the trains beginning their rise to freeway level starting at Northeast 75th Street. Under the new proposal, they would rise above ground en route to the Northgate station starting at Northeast 85th Street…
“This will improve our overall construction schedule,” Endlich said. “We believe it will also have a lower net cost to taxpayers under this approach.”… According to a flier from the meeting, the proposal is expected to save $5 million to $10 million.
What? Tunneling is cheaper?
Um, I mean, er, nothing more to be seen here. Go back to the editorials on how a viaduct tunnel would be irresponsible…
If the choice is between a longer bored tunnel and building four cut and cover tunnels I could see why they expexct it to be cheaper. It would be nice to have more details.
once you have the machines in the ground, i could see how it might be less expensive than switching to another method.
cut and cover is also pretty disruptive and can impact tax revenue generating businesses, a hidden cost which doesn’t exist with tunneling.
also, maybe ST is having a lot of success with the TBMs and wants to continue with that method as the experience level with it continues to increase.
i would like more information on this though.
“once you have the machines in the ground, i could see how it might be less expensive than switching to another method. ”
This might be especially true if ST has reason to believe soil conditions are better up there.
Cheaper because they don’t have to support 4 bridges with cut and cover tunnels and related support structures … will also mitigate a lot of the traffic problems and required modifications to surface streets needed to support all the dump trucks, etc … that would otherwise be using residential streets in the neighborhoods near the stations.
Fewer utilities to relocate as well.
How many tunnel boring machines are involved in University Link/North Link construction? Can they be reused for different phases? I thought I read somewhere that the University Link TBM would be discarded in the rock upon completion, so presumably there’s some reason it couldn’t be used for North Link as well?
U-Link will use 3.
The TBMs boring from Capitol Hill to Pine Street will have their outer shells become part of the tunnel so they don’t have to rip up Pine Street again. The TBMs heading to the UW station will be extracted at a pit near the UW Station. This pit would also be used to extract the tbms from North Link.
so would ST be using the extracted TBMs to work on this new proposal?
I doubt it. It’s up to whatever contractor wins the bid for North Link to source and supply the TBMs for the project. The type of TBM used varies by ground conditions and the tunneling technique that the contractor is comfortable with. The TBMs used for U-Link will probably be sold by the contractor after the job is complete. Also, as I understand the timeline, the tunneling for North Link will probably be starting before U-Link tunneling is complete.
Mmm, Sound Transit seems to be pretty clear that the TBMs are going from UW to Capitol Hill, not the other way around. See here (scroll down about 4/5 of the way).
Similarly, for the tunnels from Capitol Hill to Pine Street, the Capitol Hill station page says:
“When the TBM reaches Pine Street, the TBM will be disassembled and transported back to the Station site, where it will be reassembled to dig the second tunnel between Capitol Hill and Pine Street.”
Even though the ST website also says somewhere else that, after digging the second tunnel, the TBM has to be left in place because it can’t be taken up to the surface, like you said. WTF???
It’s just the shell, or shield of the TBM that will be left in place. They are boring the northbound tunnel first, where there is room to extract the TBM by digging a pit in the vacant lot next to the Paramount. The southbound tunnel is being bored second, and there is no room to dig a pit to extract the TBM because it will be emerging right under Pine Street. They will leave the shell in place and just disassemble the TBM and take its parts out through the tunnel. Hope my explanation makes sense.
Zed thanks for the good info.
Yep, makes sense. Thanks.
It looks like the brochure that was recently added to the North Link site at ST.org shows the revised tunneling plan. The map shows the deep bored tunnel starting at 85th st, instead of 75th st as previously indicated.
http://projects.soundtransit.org/Documents/pdf/projects/link/north/Fact_NLink_0510.pdf
it was going to be really difficult to squeeze the train into the structure that is the 80th Street interchange. There were engineering issues and it just made more sense to go underground. A lot less surface impacts and the site around 85th gives us better staging.
I’d like to see the completion date pushed up. I’d love to see a 2018 opening.
I don’t think this pushes up the completion date, it just makes the Roosevelt Station-North Portal tunnelling get done quicker.
I know, just griping that North Link isn’t getting built faster. I’d be riding it today if it was open. ;-)
that makes a million of us…
We’re on our way to having a subway from 85th St. in North Seattle all the way to the International District. When this line is open the whole way about 10 years from now, many people will experience at least 36 minutes each day (18 each way) when the only visible sunlight will be odd shafts of daylight at the stations.
It’s going to be a game changer to be able to reliably travel from Northgate to Westlake in 13 minutes — or Roosevelt to Capitol Hill in 8 minutes — or Westlake to UW to 6 minutes — and it’s going to make for a different experience of living in this city. I grew up in Chicago and took the subway every day to school for a while. It was fun and memorable and it was very empowering as someone without a driver’s license to have that mobility.
Doesn’t seem like this will make any difference in travel time – for a pleasurable ride I’d probably prefer elevated, but this will certainly cause less disruption for the neighborhood, both during and after construction.
The only thing I can say about that is that an elevated structure certainly makes for a better ride. Ride the…2(1?) train in NYC and it’s very cool. Or the F or A train in Brooklyn.
HOWEVER, I want this thing done! And I’d like it done without destroying some peoples homes.