SF Muni Metro Central Subway construction

[lpetrich]

Welcome to SFMTA Central Subway | SFMTA Central Subway

Preliminary construction has started, mainly utility relocation and preparation for tunneling. Full-scale construction will start next year.

Tunnel Construction | SFMTA Central Subway That page has an nice computer-graphics video of a tunnel-boring machine in action. It's heavily automated, complete with automated installation of tunnel lining. This approach will be used instead of cut-and-cover, because it causes much less surface disruption.

The route starts at the surface at 4th & King Sts., near the Caltrain station, and goes north in 4th St. After a station at 4th & Brannan, it goes underground at I-80, having a station at Yerba Buena / Moscone Center. It crosses Market St. to a station at Union Square / Market St., and continues northward in Stockton St. Its last station is at Chinatown, between Clay St. and Washington St. The tunnel continues further to Columbus Ave. and Union St., near Washington Square Park, where it ends. A possible future North Beach station?

The TBM will be a necessity for avoiding climbing the hill at the northern part of the route. Stockton St. has a tunnel from just south of Bush St. to between California and Sacramento Sts. Union Sq. / Market St. shows the depth of that station's tracks -- about 5 stories below street level. That will be enough to go beneath the Market St. BART/Muni-Metro tunnel.

[lpetrich]

San Francisco's Central Subway project nabs $942 million - San Francisco Business Times

San Francisco’s Central Subway project has gotten the OK from the federal government for $942.2 million — or about 63 percent of its $1.5 billion budget.

From the Federal New Starts program; the rest of the money will come from local and state sources.

Central Subway will move San Francisco in right direction | Examiner Editorial | Editorials | San Francisco Examiner

With the federal contribution announced Thursday, the project is now fully funded. And work is already under way to prepare for the massive boring machine that will drill the new subway tunnel.

Checking on Timeline | SFMTA Central Subway, they are expecting to open it in 2019.

Tunnel Boring Machine Update: Photos of the Central Subway’s tunneling machines | Central Subway Blog -- as it says.

[quantummechanic90]

I can not wait until it is finished. I will be able to get to work a lot easier with this system in operation. Now it's by bike to get to work. The joy of working in IT.

[lensovet]

nice!

[lpetrich]

Muni subway plan to appease North Beach - SFGate

Muni's boss has a plan to silence the vocal opposition in North Beach to the Central Subway construction project - he wants to take a major step toward extending the line from Chinatown into North Beach itself.

... However, the plan has also called for digging up a section of Columbus Avenue in North Beach so the huge subway-drilling machines can be pulled out of the ground when the job is done.

That has brought screams of protest from merchants who fear the disruption will kill their businesses and residents who think it will wreck the neighborhood. There's even been a lawsuit filed.

That would be welcome if they could pull it off.

[lensovet]

Muni subway plan to appease North Beach - SFGate

Muni's boss has a plan to silence the vocal opposition in North Beach to the Central Subway construction project - he wants to take a major step toward extending the line from Chinatown into North Beach itself.

... However, the plan has also called for digging up a section of Columbus Avenue in North Beach so the huge subway-drilling machines can be pulled out of the ground when the job is done.

That has brought screams of protest from merchants who fear the disruption will kill their businesses and residents who think it will wreck the neighborhood. There's even been a lawsuit filed.

That would be welcome if they could pull it off.

christ, these people are going to get a subway going to their house and they are complaining?

[pebbleworm]

The central subway will replace a 10 minute walk from Market Street to Chinatown with a very expensive streetcar that will take at least as long if you count waiting on the platform. It doesn't seem like a good value to me, but it is still one heck of a lot cheaper than 5 fighter planes that don't work well. By that standard, it's a bargain!

[lensovet]

The central subway will replace a 10 minute walk from Market Street to Chinatown with a very expensive streetcar that will take at least as long if you count waiting on the platform. It doesn't seem like a good value to me, but it is still one heck of a lot cheaper than 5 fighter planes that don't work well. By that standard, it's a bargain!

the point of this subway is to make caltrain actually usable, not to get people from chinatown to ride to market st. also, a 10-minute walk for me today might not sound so easy when i'm 70.

[lpetrich]

Central Subway tunneling machines set to arrive in San Francisco; digging expected to start in June | Will Reisman | Transportation | San Francisco Examiner

The two massive machines — which each are more than 300-feet long — will take about four to six weeks to assemble once they arrive from China, according to Sarah Wilson, an engineer on the project. Once built, the machines will be dropped into a launch box below Fourth Street, where they will start drilling at about 40 feet per day, Wilson said.

Meet the TBMs | SFMTA Central Subway

The two tunnel boring machines (TBMs) that will excavate and construct the Central Subway tunnels are named Big Alma, after “Big Alma” de Bretteville Spreckels, and Mom Chung, after Dr. Margaret “Mom” Chung. These historic San Francisco women helped shape the San Francisco of the past, just as the Central Subway will help form the San Francisco of the future.

[lpetrich]

There's a certain problem. There's a rather steep hill between Market St. and Chinatown, and one won't enjoy walking up it.

Construction Updates | SFMTA Central Subway, First Central Subway Tunnel Boring Machine to Pass Beneath Existing BART and Muni Metro Tunnels, Extending T Third Line Tunnel Into Union Square | SFMTA, (Press Release), North Beach/Pagoda Palace FAQs | SFMTA Central Subway

TBM Mom Chung successfully tunneled under the BART/MM tunnel early last December, complete with making the tunnel's 36-degree curve from 4th St. to Stockton St. in less than a city block. TBM Big Alma is expected to do likewise some time this month. Mom Chung is digging the southbound tunnel and Big Alma the northbound one, but both TBM's are digging their tunnels northward. Mom Chung's tunnel is about 10 feet below BART's, and Big Alma's may also have that depth. The TBM's should complete their tunneling by spring, reaching the old Pagoda Palace property at Columbus Ave. and Powell St., near Washington Square Park, where they will be removed. This will allow for further extension to North Beach.

I was a bit surprised that they are going below the BART/Muni tunnel rather than above it, because that makes the stations rather deep. The route and stations:

(4th St.)
4th and King (existing; at the Caltrain station) - surface
4th and Brannan - surface
(tunnel portal just south of I-80)
Yerba Buena / Moscone Center - tunnel
(Stockton St.)
Union Square / Market St. (near Powell St.) - tunnel
Chinatown (Washington St.) - tunnel
(Columbus Ave.)
(End of tunneling at Powell St.)

[lpetrich]

This may be too droll for some of you people, but some Muni staff members have created Twitter accounts for the two Tunnel Boring Machines:

Mom Chung (MomChungtheTBM) on Twitter
Big Alma (BigAlmatheTBM) on Twitter

Big Alma has now reached Market Street and is crossing under the BART tunnel.

[lpetrich]

The two tunnel boring machines have completed their work, and they will soon be disassembled and extracted from the North Beach extraction pit. They will likely be returned to their manufacturers for refurbishing and tunnel-boring duty elsewhere. They might even be returned to San Francisco Bay for digging tunnels for BART underneath San Jose.

SF Central Subway tunnel-boring phase reaches milestone | Transportation | San Francisco | San Francisco Examiner
Central Subway tunnel boring machines will live on | Transportation | San Francisco | San Francisco Examiner
▶ Big Alma Emerges - YouTube

Construction Update | May 31 – June 9 | Central Subway Blog - getting ready at the extraction pit.
Construction Update | June 7 – June 16 | Central Subway Blog - Mom Chung breaks through on June 2
Construction Update | June 14 – June 23 | Central Subway Blog - Big Alma breaks through on June 11

[lensovet]

There's a certain problem. There's a rather steep hill between Market St. and Chinatown, and one won't enjoy walking up it.

Construction Updates | SFMTA Central Subway, First Central Subway Tunnel Boring Machine to Pass Beneath Existing BART and Muni Metro Tunnels, Extending T Third Line Tunnel Into Union Square | SFMTA, (Press Release), North Beach/Pagoda Palace FAQs | SFMTA Central Subway

TBM Mom Chung successfully tunneled under the BART/MM tunnel early last December, complete with making the tunnel's 36-degree curve from 4th St. to Stockton St. in less than a city block. TBM Big Alma is expected to do likewise some time this month. Mom Chung is digging the southbound tunnel and Big Alma the northbound one, but both TBM's are digging their tunnels northward. Mom Chung's tunnel is about 10 feet below BART's, and Big Alma's may also have that depth. The TBM's should complete their tunneling by spring, reaching the old Pagoda Palace property at Columbus Ave. and Powell St., near Washington Square Park, where they will be removed. This will allow for further extension to North Beach.

I was a bit surprised that they are going below the BART/Muni tunnel rather than above it, because that makes the stations rather deep. The route and stations:

(4th St.)
4th and King (existing; at the Caltrain station) - surface
4th and Brannan - surface
(tunnel portal just south of I-80)
Yerba Buena / Moscone Center - tunnel
(Stockton St.)
Union Square / Market St. (near Powell St.) - tunnel
Chinatown (Washington St.) - tunnel
(Columbus Ave.)
(End of tunneling at Powell St.)

i'm not surprised they went under, the original tunnels were made using cut and cover methods, so there's not much soil to use to bore another tunnel on top of the existing ones.

[lpetrich]

So going above the BART/Muni line would have meant a too-shallow tunnel? That makes some sense, because the top of the tunnel would have been very close to street level.

BTW, both TBM's have been removed from the extraction pit in North Beach, complete with Twitter drollery about it.

[lpetrich]

Construction continues there.

Central Subway Tunnel Project Wins Award of Merit From ENR | Central Subway Blog

Congratulations to the Central Subway Team for achieving an Award of Merit for best transportation project of 2015 from Engineering News record, a weekly magazine highlighting the construction industry. The award was given for the completion of the Central Subway Tunnel. The Central Subway Tunnel Project was cited for completing an intricate project on time and within the approved budget.

Of the four stations, 4th and Brannan is a surface station, while Yerba Buena / Moscone, Union Square / Market Street are being constructed by cut and cover, and Chinatown by the New Austrian Tunnelling Method a.k.a. the Sequential Excavation Method.

4th and King Trackwork Installation | Central Subway Blog
When the Muni Metro was first built out to the Caltrain station, the tracks there ran in King St. northeast - southwest. When the T-Third line was built, it extended southeastward in 4th St. from 4th and King Sts. and had a northeast - southeast connection. This new trackwork has:

• King St.: northeast - southwest
• 4th St.: northwest (to the Central Subway) - southeast (T-Third, to 3rd St. and southward)
• Northeast - southeast track connection

The new tracks show no evidence of other possible track connections.