Uncrooking San Francisco's Crookedest Tunnel

How do we figure out the best way Caltrain and HSR get to the Transbay Center?
Tearing down a freeway?
Rerouting a planned train tunnel that's already EIR certified?
Build housing and offices on a relocated rail yard?

Crazy? Not really considering there's not enough money for the tunnel.

When the Mayor's Office suggested "Let's be San Francisco and Take Down the Freeway", the earth shifted a bit, but we're used to that in quake prone SF. The proposal calls for tearing down I-280 north of 16th Street and converting the 30 acre Caltrain railyard and (and some freeway land) into a mixed use neighborhood.  At an estimated worth of $228 million, some of that money could help fund the $2.5 billion construction of the downtown extension tunnel (DTX).

Additional Posts on the Caltrain Downtown Extension and the Railyard Redevelopment
Caltrain Railyard Hide and Seek - a look at where to relocate the railyard if the 4th & King yard is redeveloped
(Ped) Tunnel Vision - a look at the pedestrian tunnel options to link the Transbay Center with BART and Muni Metro on Market Street
Poll: Where should BART go in SoMa? - a look at possible alignments from a 2nd Transbay Tube through SoMa and on to Geary Street. Regarding Caltrain, how would a 2nd Transbay Tube best serve Caltrain to the East Bay, and how would two new tunnels with stations in SoMa best serve San Francisco and the region?

Another component of the "Let's be San Francisco" presentation, was considering rerouting the rail tunnel to the Transbay Center. The Caltrain Downtown Rail Extension (DTX) calls for tunneling from the current Caltrain Railyard up to the Transbay Terminal and taking three sharp turns that will dramatically slow trains, increasing travel times and reducing tunnel capacity. Rerouting the DTX tunnel could straighten out much of the tunnel, and improve travel times and capacity.  Might rerouting the DTX tunnel down Mission Street to parallel BART and Muni on Market Street with a new station connecting to Powell or Civic Center create a grand opportunity that makes for a better rail system and fosters more economic opportunity, all while improving the tunnel and coming at no greater cost?

Read on to learn more about the options and see larger versions.

The Challenges

Are these ideas crazy? Ill advised? Misguided? Financially impractical?  Not really considering there's not enough money for the tunnel and there are many other challenges with the current plans to have rail reach the Transbay Transit Center. The current Caltrain DTX and Transbay Transit Center plan has great promise and does many things right. However, there are four critical challenges with the current design.

1. The 16th Street crossing conflicts: rail, street, freeway, buses, pedestrian and bike don’t mix well under many plans
2.  Rail capacity is limited due to the I-280 pillars
3.  The three sharp turns in the DTX tunnel limit speed and capacity
4.  The tunnel and entire DTX project is currently underfunded and would only receive needed funding by 2022 or later. 

I’ll be going into all the issues related to getting rail to the Transbay Center over several posts. This post will focus on the DTX alignment and alternatives.

Image: Troy Holden via Streetsblog SF

The Current DTX Plan

The current plan calls for Caltrain and HSR trains to travel along the existing rail right of way between the northern Potrero Hill Tunnel portal at Mariposa Street up to the Caltrain railyard between Townsend and King Streets. The DTX plan would have trains take three 90 degree turns before reaching the Transbay Center:

• Turn east 7^th & Townsend in a trench
• Turn north at Townsend and 2^nd Street in a tunnel
• Turn east at 2^nd Street and Howard in a tunnel

That seems like a lot of turns, especially if they have to travel at the speed of a bicycle. Trains would decend into a tunnel beginning at 6th Street and Townsend. An underground Caltrain station at 4th and Townsend would add to the existing Caltrain terminal station at 4th & King. 

Without sufficient funding for the tunnel, we're at a point where it would be prudent to reevaluate the cost, funding and route of the planned DTX. By increasing land value, both tearing down I-280 and relocating the yards could generate more revenue to help fund the project. Could realigning the tunnel and adding a station do the same? Changing the alignment would be an uphill battle to put it mildly. With environmental work finished and engineering planning underway, changing the alignment would cost extra money to conduct a new environmental study and begin new engineering plans.

Even so, maybe one of the alternative routes could prove to be a cheaper tunnel, or generate more funds, or create new connections with other rail systems that would gain support and funding from other groups. 

Following are maps of the current plan and 4 new alternative alignments, 2 of which were presented by SFCTA. Each alignment has a designated "name" and also referenced by the streets they follow. The names are based on historic elements in the area such as old geographic points (e.g. Steamboat Point at Brannan and 2nd), or actual old street names (6th Street was once called "Simmons Street"). I've named the current planned DTX alignment the "Steamboat Rincon" alignment that follows Townsend and 2nd streets because it passes through the historic Steamboat Point and Rincon Hill.

I looked up the EIR document to see what alignments were originally considered for DTX. As the map shows below, all of them effectively went from 4th and King to the Transbay Center via 2nd, 3rd, Essex, First or Beale streets. None of them considered starting the tunnel earlier or connecting to other transit systems at multiple points.

Whatever tunnel and stations get built, we should be considering what we're asking for and what's most important. Simply stating this is a tunnel to get to the Transbay Center is missing the point. We're creating a valuable piece of infrastructure that should work for at least a century into the future and work for not just Caltrain, HSR, and downtown, but benefit the entire region, including other transit operators, residents and commuters. Below is a list of goals that each tunnel alignment and station location can be measured against.

Goals for Caltrain DTX and station locations

Provide reliable, efficient, and comfortable train service (local, regional and intrastate) from San Francisco that serves residents, commuters, travelers, and shoppers

Link Downtown San Francisco to the region and state via train (1st to the Peninsula, later to rest of region)

Create a rail alignment and train stations that will beneficially serve as much of San Francisco's transit and intercity train needs as possible, but within an achievable cost.

Create rail stations (Transbay Center and others) that can best link to other transit systems in the city and the region

Create rail stations (Transbay Center and others) that are in close proximity to dense employment centers and dense housing

Ensure that each station has high pedestrian connectivity from all directions, that are safe, and attractive to use. Ensure safe and attractive bicycle connectivity as well.

Create stations and rail alignments that will be best positioned to link and support with future rail transit (2nd Transbay Tube for BART, 2nd Transbay Tube for HSR, BART to Richmond, etc.)

The Solutions

Rerouting the DTX route and tunnels would greatly improve travel times and rail capacity (due to not having slow trains clogging up the tunnel). Several alternatives considered during an San Francisco County Transportation Authority (TA) design charrette were presented by the Mayor’s Office.

East Route

• Tunnel via 4th Street through Mission Bay and on to the 2nd Street Tunnel already planned. The Mission Bay Station is moved 1-2 blocks west to 3^rd or 2^nd & King.

West Route

• Tunnel via 7th Street alongside Mission Bay and arcing through SoMa north of Townsend to the Transbay Center. A Mission Bay Station could exist at a spur to 4^th & King, or somewhere along 7^th St south of Townsend. 

Although these are only preliminary alignment considerations, they are filled with opportunities and some challenges, much like the current DTX planned alignment. Before going into the details of the options I want to highlight how solutions to problems are found, and sometimes found with limitations.

Often when searching for a solution to a problem, the solutions envisioned only address the problem at hand. However, they don't always look at the margins and into the bigger picture, the less obvious or less conventional solutions. Removing I-280 and developing the railyards are a great example. When DTX and the Transbay Center project was planned, never were these two ideas presented over the early years of planning. However, we now see that doing both will not just address funding and street crossing challenges, but also reconnect three neighborhoods (Mission Bay, Potrero Hill, and SoMa) and make for a better place to live, work and play and thus a better city.

Image: CaHSRA via GreenCaltrain.com


Readdressing the rail tunnel alignment could create similar global solutions never imagined when only looking to get rail to the Transbay Terminal from the Caltrain Yards.

The Rail Alignment Options

As mentioned earlier, the TA and Mayor’s office presented 2 alternatives to the Planned DTX alternative. Both of them considered having a Mission Bay station, but no additional stations, say at 16^th Street, or in SoMa, where employment growth continues.

Image: SF Gate, Razing I-280

Why not route the tunnel so that it could benefit, not just Caltrain, HSR and the existing stations (4^th & King, Transbay), but also promote regional transit with transfers to other modes like BART, Muni Metro, and Muni buses. Similarly, alternatives compatible with a future Second Transbay Tube (HSR/Caltrain and BART) should be considered. Finally we should explore options that might relieve capacity stress on the BART’s two downtown stations (Montgomery and Embarcadero).

Read on and take a look at the 5 options considered with analysis of their pros and cons and opportunities.

The Grand Curve: 7th Street to Transbay

The Grand Curve is 7% shorter than the planned Steamboat Rincon alignment. Such an alignment could still provide a Mission Bay Station, but on the neighborhood's west side (on 7th St) rather than its north side (on Townsend). A SoMa station is possible, although placing it at Moscone Center may be too close to the Transbay Center to be practical. A pedestrian tunnel should be constructed to link the Transbay Center to Embarcadero or Montgomery BART stations to allow for and encourage transfers between BART and Muni Metro with Caltrain and HSR.

	Pros	Cons
Curves & Tunnel Capacity	Large curve from 7th & Townsend to Howard and 4th   No sharp curves   Greatly improved train speeds due to wide curve	May require 1 medium curve from Howard to Transbay Center between 3rd and 2nd streets.
Stations	Mission Bay 7th Street Station.  Potential Moscone Howard Station.	Removes  4th & Townsend Station  Moscone Howard may be too close to Transbay Center to be a practical station
Tunnel Alignments		Path goes below private land and buildings. Buildings, including Hall of Justice and Moscone Center could be affected either structurally or by vibrations unless tunnel is sufficiently deep.
Access Opportunities	Access to Mission Bay & Potrero Hill and UCSF. Transfers to 22 Muni BRT Access to Moscone Convention Center and Yerba Buena District Transfers to T-Third at Moscone Station.	No direct access to North Misson Bay or South Beach No stations close to AT&T Park.
Length (19th Street to Transbay Center)	2.2 miles, ~800 feet (-7%) shorter than Townsend 2nd Route
Planning/EIR		New EIR and engineering for the entire route
Cost	Possibly cheaper construction than planned DTX tunnel due to tunnel boring the entire length.	New EIR and engineering for entire route A Moscone Station would add to cost.
Politics	Removing freeways has a strong track record in San Francisco A Moscone station on Howard may be enticing.	Changing tunnel is politically challenging Moscone and other building owners may protest deep tunnel under  them.

The Grand Curve is not a bad idea. However grand it is, it may just go below too many buildings for those owners. If just a few small (or large) owners banded together, this alignment could fall apart politically.

Mint Harris: 7th Street to Mission Street

Linking BART/Muni to Caltrain here allows residents north and east of Civic & Center and Powell to shorten their bus/train ride by up to 10 minutes. This could be a greater savings when traffic on Market Street is factored in. Linking Caltrain at Civic Center/Powell also reduces stress at BART's Montgomery and Embarcadero stations which are virtually at capacity. If the only link between Caltrain and BART is at Embarcadero, then Embarcadero will easily become overcrowded. 

Creating a station at 6th & Mission gives South Bay and Peninsula commuters better access to the emerging Mid-Market job center as well as Civic Center area. Conversely, commuters from the Richmond, Sunset, and Haight would be able to transfer to Caltrain much earlier, and avoid crowded buses shuffling down Market Street all the way to the Transbay Center. Finally, BART commuters transferring to Caltrain could choose either the crowded Embarcadero or the less crowded Powell Street. We can assume most East Bay BART commuters might transfer at Embarcadero (unless it is still very crowded), but folks coming from the 16th St Mission, 24th St Mission, Glen and Balboa Parks, would transfer at Powell Street to reach Caltrain.

Although the route is 8% longer, the opportunites created by a Mission 5th Street Station may outweigh the extra length and costs associated with rerouting DTX.

	Pros	Cons
Curves & Tunnel Capacity	1 major curve at 7th & Mission Improved train speeds
Stations	Mission Bay 7th Street Station between 16th and Mission Bay Blvd.  Mission and 5th Street between 6th & 5th.	Removes current 4th & King Caltrain station.
Tunnel Alignments	Follows under streets much of its journey.	Path goes below private land and buildings at 7th and Mission, and near Transbay Center.  Possibly goes under Moscone Center.
Access Opportunities	Access to Mission Bay, Design District & Potrero Hill.  Transfers to N-Judah and 22 Muni BRT.  Access to Union Square, Mid-Market & Civic Center. Transfers to T-Third at Union Square Station.  Links to BART & Muni Metro at 2 stations.	No access to South Beach.  Railyard development farther from a train station than 4th & Townsend station.  AT&T Park not as close.
Length (19th Street to Transbay Center)		2.3 miles ~900 feet (+8%) longer than Townsend 2nd Route
Planning/EIR		New EIR and engineering for the entire route
Cost	Possibly cheaper construction than planned DTX tunnel due to tunnel boring most of the length.	New EIR and engineering for the entire route.  Building extra stations (e.g. Mission & 5th St) adds cost.
Politics	Removing freeways has a strong track record in San Francisco.  A Mid-Market/ Moscone station on Mission may be enticing.	Changing tunnel is politically challenging.  Building owners may protest deep tunnel under them.

This option gets almost everything you could possibly want, save for the need to do an EIR and design of the tunnel.

Long Bridge: 4th Street to 2nd Street

This route was proposed at the SFCTA design charrette. Baseball fans will especially like this alignment as it gets fans even closer to the ballpark than the current 4th & King station. The main advantages of this alignment are being the shortest and 13% shorter than the current planned Steamboat Rincon alignment. In addition, this alignment would only require new environmental and engineering work from Brannan Street south - approximately half the tunnel length. 

The 3rd and King Station could be situated such that the south end is located south of Mission Creek and McCovey Cove, while the north side is at King Street in North Mission Bay.

	Pros	Cons
Curves & Tunnel Capacity	2 major curves at 16th & 4th and 2nd & Howard 1 minor curve at 2nd & Townsend Improved train speeds	1 tight curve at 2nd & Howard entering the Transbay Center.
Stations	3rd & King Station	Moves current Caltrain station 1 to 2 blocks east.  No additional stations.
Tunnel Alignments	Path remains below street the vast majority of its length.	Path goes below private land and buildings at Mission Creek, including AT&T Park.
Access Opportunities	Access to Mission Bay & South Beach. Transfers to T-Third and N-Judah at King Street station.  Close to AT&T Park and Mission Rock development.	No access to 16th Street Corridor.  No additional access to BART
Length (19th Street to Transbay Center)	2.0 miles, ~1500 feet (-13%) shorter than Townsend 2nd Route
Planning/EIR		New EIR and engineering for tunnel south of Brannan
Cost	Possibly cheaper construction due to 13% shorter tunnel.	New EIR and engineering for tunnel south of Brannan.
Politics	Removing freeways has a strong track record.  Half of the tunnel would not be changed (north of Brannan)	Changing tunnel is politically challenging.  AT&T Park and other building owners may protest deep tunnel under them.

The route roughly follows the "Long Bridge" that once crossed Mission Bay. However, Long Bridge actually follows what is now 3rd Street.

Simmons Howard: 6th Street to Howard Street

Although this route has challenges, it could meet most of the needs. Transfers with the Muni T-Third are accomplished at Howard 4th Street station next to Moscone Center. Transfers to BART are accomplished at the Transbay Center. Finally, the new development on the old Caltrain railyards has a station sitting in the middle of the development.

This option also allows for the Mission Bay Station to straddle Mission Creek, providing access to both sides. The downside of the option is that a Mid-Market BART transfer is not possible as Howard Street is too far from Market Street for a practical pedestrian link. In addition, the two turns in Mission Bay at each end of Owens Street are mild, but would in some ways still slow down service.

	Pros	Cons
Curves & Tunnel Capacity	1 major curve at 6th & Howard 2 minor curves  at 16th and Owens and at Mission Creek Improved train speeds	May require 1 medium curve from Howard to Transbay Center between 3rd and 2nd streets.
Stations	6th and King Street Station between Townsend and Mission Creek.  Howard and 4th Station.	Moves current Caltrain station 1 to 2 blocks west.
Tunnel Alignments	Path remains below streets most of its length.	Path goes below private land and buildings at 7th and Mission, and near Transbay Center
Access Opportunities	Access to Mission Bay, SoMa & Design District. Transfers to N-Judah. Access to Union Square & Mid-Market.  Transfers to T-Third at Moscone Station.	No access to 16th Street Corridor or South Beach. No additional links to BART.
Length (19th Street to Transbay Center)	2.1 miles, ~250 feet (-2%) shorter than Townsend 2nd Route
Planning/EIR		New EIR and engineering for the entire route
Cost	Probably equal cost of construction.	New EIR and engineering for the entire route. Building extra stations (e.g. Mission & 5th St) adds cost.
Politics	Removing freeways has a strong track record in San Francisco.  A Moscone station on Howard may be enticing.	Changing tunnel is politically challenging. Moscone and other building owners may protest deep tunnel under them.

The Simmons Howard has the great challenge, much like the The Grand Curve, of going right under Moscone Center. That being said, it's still shorter than the current planned Steamboat Rincon alignment, the Mission Bay station wouldn't shift too far from the current one, and a SoMa station on Howard would provide new regional transit access to this growing part of SoMa.

Steamboat Rincon - The Planned Route: Townsend to 2nd Street

The currently planned route, as shown before follows Townsend and 2nd Street and passes through three very sharp turns. Note that the current plan calls for the tunnel to start on Townsend at 6th Street, not at 16th Street as would be necessary if I-280 is torn down.

	Pros	Cons
Curves & Tunnel Capacity		3 sharp curves: 7th & Townsend, Townsend & 2nd, and 2nd & Howard. Very slow train speeds through entire path.
Stations	4th & Townsend Station between 5th and 4th streets.	No 16th Street station or SoMa station.
Tunnel Alignments	Follows under streets most of path.  All right of ways have been cleared.	Requires additional tunnel between 16th St and Townsend.
Access Opportunities	Access to North Mission Bay and South Beach.  Close to AT&T Park.  Transfers to T-Third and N-Judah at 4th & Townsend Station.	Access to UCSF Mission Bay requires crossing bridges.  No access to 16th Street Corridor, or Potrero Hill.  No new access to BART.
Length (19th Street to Transbay Center)	2.2 miles	Will require additional tunneling to go beneath 16th St and Mission Bay Blvd.
Planning/EIR	EIR complete and certified.  Engineering planning already begun.	New EIR may be required for tunnel between 16th Street and Townsend.
Cost	$2.5 billion	Funding gap exists.  Waiting for Federal Funding. May not be available until 2022.
Politics	All political forces in the city and state are in support of DTX.	Congress not reliable with funding.  Removing I-280 politically difficult due to perceived traffic challenges.

Advantages of TWO LINKS to BART

As mentioned before, having a transfer link to BART/Muni Metro at the Transbay Center would greatly benefit regional transit. Although no link is actually funded or planned right now, there have been calls for it in previous Transbay studies. Such a connection could connect to Embarcadero, Montgomery or both stations. Unfortunately as BART recently showed, these two stations are nearly at capacity, as shown by their consideration of adding new platforms under the "saddlebag" proposal. If the only link between BART and Caltrain in San Francisco is at the Transbay Center, the BART stations may become overly impacted.

That said, creating a second link between BART/Muni Metro and second Caltrain Station somewhere on Mission Street would reduce the demand such a transfer would have at Embarcadero or Montgomery. By spreading out transfer traffic to two stations, BART stations and the Transbay facility will not become overly crowded. Even if they don't become immediately crowded, having the two stations would allow for much more growth than the current DTX plan.

In addition to transfer benefits, providing a Mission Street station linked to Powell or Civic Center would also allow for Peninsula and South Bay commuters to reach workplaces in the Mid-Market and Civic Center job centers. Likewise, shoppers could easily get to the Union Square and San Francisco Centre shopping centers.  All of this would add value to San Francisco's livability, workability and land value.

2 Station solution spreads out transfer demand over 2 stations.

One station transfer at Transbay could create capacity challenges at BART stations,.

Final Thoughts

Any of these ideas would create a great improvement in transportation on the Caltrain corridor and in San Francisco. The question is, if money isn't lined up now, and it may not be for a while, can we put the current plans on hold and find out if another tunnel alignment might just be better. Secondly, may of these plans may be better than the current plan. However, the cost to step back and redo environmental studies and new engineering plans may prove too costly. That said, without a reasonable review of said costs for each alternative, we don't know whether or not rerouting the tunnel is a fool's errand or a stroke of genius.