New Connections

Why San Francisco needs the Central Subway
SPUR Report
June 20, 2007

San Francisco is planning its first subway in 35 years — a rare opportunity to advance the effectiveness of the entire Muni network. The “Central Subway” will be an extension of the T-Third light-rail line, extending from Fourth and King streets along and underneath Fourth Street, under the BART and Muni Metro tunnels, and under Stockton Street to its planned terminus in Chinatown near Clay Street.

SPUR’s three-part agenda for Muni system reform:

1. Make Muni run faster. Get transit vehicles out of traffic by building subways and rapid transit facilities. Implement transitpriority treatment. Clear the lanes by increased enforcement.
2. Fund Muni sufficiently. Give the MTA the money it needs to increase its staffing of planners, mechanics, and operators so that it can provide a reliable service: approximately $50 million
to 150 million in additional funding each year.
3. Hold staff accountable. Provide incentives for good management and efficient deployment of the Muni work force.

SPUR is a strong supporter of the Central Subway project. Improved public transit through strategic investments in infrastructure is critical to the urbanist agenda of promoting jobs and housing in cities to protect the region and the planet from sprawl. Getting transit vehicles to run reliably, efficiently and quickly, away from delays caused by car traffic and pedestrians, is the first part of SPUR’s three part transit reform agenda. Subways, of course,are extremely effective at getting transit vehicles out of traffic.

The evolution of the Central Subway projectThe concept for the Central Subway was born in preparations for the city’s first transportation sales tax, approved by voters in 1989. The expenditure plan for that tax promised improvements on four key Muni corridors: Third Street, Geary Boulevard, Van Ness Avenue, and Chinatown/North Beach. With the T-Third Street light rail line completed, and “rail-ready” BRT plans in progress on Geary Boulevard and Van Ness Avenue, the Central Subway is the last of the four corridors to be improved. Its development became especially important when the Embarcadero Freeway and its Broadway ramp were demolished, severing a connection between the Bay Area’s larger Chinese-American community and the region’s most concentrated population of Chinese immigrants, San Francisco’s Chinatown. The Central Subway will restore that connection.

The Central Subway is actually a 1.7-mile extension of the T-Third light rail line, including 0.4 miles on the surface of Fourth Street and 1.3 miles underground in a subway. When built, it will change the routing of the T-Third line. The new T-Third line will operate between its southern terminus in Visitacion Valley and its proposed northern terminus under Stockton Street at Clay Street in Chinatown. Northbound T-Third trains that turn right at King Street and run along the Embarcadero before entering the Market Street subway will instead run up Fourth Street, enter a subway north of Bryant (below the freeway viaduct), follow a very deep trajectory under the BART tunnel before turning slightly to follow the alignment under Stockton Street. The line will include a surface station at Brannan Street and three underground stations at Moscone Center, Market Street/Union Square, and Clay Street.

Passengers traveling from Visitacion Valley to Chinatown will enjoy a direct trip of just 38 minutes compared to the 51 minutes the trip will take without the Central Subway. Passengers wishing to transfer to the Market Street subway will do so at a combined Union Square/Market Street station. Total travel time between Chinatown and Market Street will be reduced from more than 22 minutes to just 12 minutes.1

These benefits are expected to increase systemwide average daily ridership by about 21,500 new boardings with an overall projected T-Third ridership of 90,000 daily boardings. Forty percent of travel-time benefits will accrue to low-income travelers. In total, the project will save users of the San Francisco transit system 7,800 hours each workday compared to the “no project” alternative. It will cost approximately $1.4 billion to construct, the equivalent of only two years of Muni’s annual operating cost, a reasonable amount for such a significant improvement to the system.

Because the project is so expensive, as is inherent in subway projects, the Federal Transit Administration gave the project a cost-effectiveness rating of “medium-low.”2 SPUR has examined ways to improve the cost-effectiveness of the Central Subway project. It is important to make the most of such significant public investments.

The Municipal Transportation Agency, the department that is planning and will operate the subway, has already implemented some suggestions by SPUR to reduce the capital cost. The alignment has been changed to eliminate one of the two tunnel portals at the southern end of the subway. The tunnel has been shortened slightly, creating a surface instead of a subway station at Brannan and Fourth Streets. Two separate stations at Market Street and Union Square have been combined into one, saving station construction costs and providing better service and more convenient transfers between the Central Subway and the Market Street subway. Station size has been reduced. SPUR believes there are few, if any, additional cost-cutting measures that are still feasible. In fact, we are concerned that reducing the size of the platforms may be unwise considering future capacity needs in the subway.

SPUR’s Central Subway Task Force has examined several ideas to improve the benefit of the Central Subway project and therefore improve its cost-effectiveness. Those recommendations are detailed below.

Recommendations to improve Central Subway cost-effectiveness1. Expedite construction of the subway. While the federal commitment to the project remains set at $762 million, total construction costs escalate dramatically every day construction is delayed. This is in part because the escalation rate for construction materials and labor is higher than the overall inflation rate. While consumer escalation has averaged less than 3 percent per years in the past decade, construction inflation has recently spiked to between 6 percent and 12 percent per year.3 At an escalation rate of 12 percent, every month the project is delayed increases its cost by 1 percent. The Federal Transit Administration has warned that the Central Subway risks losing its federal commitment of $762 million if the project does not complete its preliminary engineering phase and move toward final design by September.

The Central Subway is an expensive project, but it will bring rapid transit to the most congested part of the city.

The MTA is close to completing an update to its financial plan for the construction cost estimate for the Central Subway. Most of the $1.4 billion in costs have been identified. Finding the additional approximately $76 million necessary to complete this project ought to be the city’s first capital priority.

The array of funding sources and savings compiled for the Central Subway show the project is almost fully funded. Proposition 1B amounts are subject to final approval by the California Transportation Commission. The value-engineering savings represent the savings from changes to the project proposed in 2006. The MTA is re-evaluating the proposed costs and is likely to increase the total based on construction inflation. Sources: Federal Transit Administration, Metropolitan Transportation Commission, Municipal Transportation Agency.

2. Extend the subway into North Beach immediately and to points beyond North Beach in the future. No other change to the Central Subway project could make it more worthwhile than extending it beyond its current proposed underground “dead end” at Clay Street. The terminus at Clay and Stockton results in an inability to serve dense and transit-deficient neighborhoods to the north, including Russian Hill, North Beach, Telegraph Hill and Fisherman’s Wharf. In addition, it results in operational inefficiencies, in that it would be difficult or impossible to eliminate or scale back duplicative service and permit efficient transfers. A Washington Square station would not only serve a very dense residential area, but it would be a convenient location for interface between bus service and the subway and would make it possible to reduce surface bus service on Stockton Street, thereby saving operating expense every year.

An extension of the Central Subway to a Washington Square station would be relatively simple. The MTA plans to extract the tunnel boring machines from the tunnel by bringing them to the surface near Washington Square. Their current plan is to simply cover the hole in the ground after extracting the machines. It is important to note that this was approved by the Federal Transit Administration as a “construction variant,” not as the groundwork for a future extension of the subway, because such an extension would be considered a substantial variation from the approved project and would subject the project to delay for further analysis. If the Central Subway is phase 2 of the T-third line, then the extension to North Beach should be considered phase 3.

SPUR recommends that planning for this phase of the Central Subway be commenced as soon as phase 2 is approved for final design. The planning should consider the following factors:

  • The urban design of the portal where the tunnel comes to daylight as well as the North Beach surface station. Washington Square is a beloved and historic neighborhood park that should not be damaged by a new portal or substantially cut off from public use during construction.
  • Muni operations should be made more efficient by taking advantage of transfer opportunities between other transit lines and the Central Subway.
  • Traffic flow should be preserved as much as possible, and pedestrian and bicycle safety should be enhanced as part of the project.
  • Future plans to extend the light-rail line to Fisherman’s Wharf, Van Ness Avenue, and points further west should be considered.

By beginning the planning immediately, the construction of the Washington Square station can begin concurrent with the completion of the subway, so that by the time the subway is ready to carry passengers, it can carry them to North Beach as well as to Chinatown, and Muni can realize the operational efficiencies and greater patronage that this station would afford.

3. Consider a shallow subway. Serious study should be undertaken of the use of a shallow subway. A shallow subway is built by cut-and-cover (as opposed to the tunneled subway currently proposed). It would be immediately below the surface and would not have a mezzanine, making it both easier to access from street level and possibly cheaper to build. This subway would cross Market Street at the level of the Powell Street Station mezzanine, resulting in easier access from the street as well as much more convenient transfers between lines, especially at Market Street, where the current plan calls for a very deep Union Square Station that would involve a long walk and great changes in level to get to the Powell Street Muni or BART platforms.

An argument against cut-and-cover tunneling is the significant disruption on the surface.In this alternative, the shallow subway would be constructed with a modified cut-and-cover method, where a shallow excavation is followed by a re-decking of the roadway, which is restored to normal operation. Most of the construction takes place under this deck. We don’t know whether or not a shallow subway would result in better operations and reduced cost, but it is definitely worth a careful examination.

SPUR recommends extending the Central Subway to Washington Square in North Beach and, some day, beyond to Van Ness Avenue at the surface. The benefit of linking to passengers on other bus and rapid-transit lines far outweighs the added cost of the surface extension.

4. Ensure sufficient capacity. In order for the Central Subway to be cost-effective, its capacity must be sufficient to handle the maximum amount of ridership that it could be expected to attract. The 200-foot platforms currently planned should be lengthened to ensure that three-car trains can be accommodated. The Breda cars in operation today are 75 feet long. SPUR recognizes that three-car trains will extend into the intersection at some of the surface stations, but believes that such a condition is a minor problem compared to the need to meet transit demand and notes that cable cars stop in the middle of the intersection and some of Muni’s light-rail vehicles currently extend into intersections when operating long trains. Subway stations are extremely difficult and expensive to enlarge after they are built. It’s probably not a good idea to cut costs by building stations that are apt to be too small.

5. Ensure easy and convenient transfers with bus routes and future subway expansions. Careful and comprehensive planning of bus routes serving the corridor and the relationship to Central Subway station locations should be undertaken in order to provide coordination of service and more attractive and speedy transfers. By this means it would be possible to eliminate duplicative service while providing a higher level of service.

Specifically, the 45-Union/Stockton bus should re-routed from Stockton Street toward the Financial District and the Transbay Terminal. Transfers between the Central Subway at the Washington Square station and the 45-Union/Stockton would serve passengers traveling between Union Square and Union Street and should be made easy and convenient. If the line is extended as far as Van Ness Avenue, the 30-Stockton bus could be terminated at Van Ness and North Point, where passengers could transfer to the Central Subway line for quick travel to Market Street. Some service will have to remain on Stockton Street because of the subway will have only one station on Stockton Street.

Many ideas were considered but ultimately rejectedIn its analysis of the Central Subway, SPUR considered but rejected some ideas to reduce the cost and increase the benefit of this project.

Use the subway for both bus and rail, or for buses only. Seattle’s Sound Transit is currently building a combination bus-rail tunnel, and has successfully used bus-only tunnels for a while. Bus-only tunnels are also successful in Germany and Australia. SPUR concluded that a combination bus-rail tunnel is infeasible due to the high frequency of transit vehicles we will operate and the difficulty in safely managing high-frequency service of different kinds of vehicles in the same constricted underground lane.

A bus-only tunnel is feasible, but was rejected as a recommendation because buses may not provide the capacity necessary in the future and because it is unlikely the federal “new starts” commitment of $762 million would be available for a non-rail project. Rail transit usually attracts more choice riders than buses because trains provide more comfort and space than buses. Also, because rail vehicles carry more passengers, they incur a lower operating cost per trip. Furthermore, this option would reduce the cost only marginally: the savings would only be in not laying the rail and in the differential between the cost of buses and the cost of rail vehicles.

A bus-only tunnel is feasible, but was rejected as a recommendation because buses may not provide the capacity necessary in the future and because it is unlikely the federal “new starts” commitment of $762 million would be available for a non-rail project. Rail transit usually attracts more choice riders than buses because trains provide more comfort and space than buses. Also, because rail vehicles carry more passengers, they incur a lower operating cost per trip. Furthermore, this option would reduce the cost only marginally: the savings would only be in not laying the rail and in the differential between the cost of buses and the cost of rail vehicles.

Abandon the tunnel altogether and provide surface operation. This option entailed major changes in proposed operation of the T-Third extension. The line would cross Market Street at Third Street instead of Fourth Street, and run up Kearny instead of Stockton. It would have had a major impact on traffic operation and provide much slower transit service compared to a subway. It would have served more jobs due to its proximity to the Financial District, but fail to serve Chinatown, and connect the it with the rest of the Bay Area. Also, it is unlikely this proposal would have been eligible for the federal “new starts” money.

Shorten the tunnel substantially by constructing its southern portal near Union Square and the Stockton Tunnel. This option entailed two-way surface operation up Fourth Street and across Market Street where the rails would enter the tunnel in one or two portals near Union Square and/or the Stockton Tunnel. The cost savings for a shorter tunnel would have been substantial, but there are several flaws that cumulatively were considered “fatal” by SPUR’s analysis. Traffic operations on Fourth Street would have been severely affected. Creating a new rail crossing on Market Street would have incurred operational challenges that may have been insurmountable. Finally, there is probably insufficient right-of-way for two-way rail operation on Stockton Street.

This idea would likely still be eligible for the federal new starts money, but would be considered a substantial change, requiring a revision of the environmental impact statement and causing a delay of more than one year and a subsequent increase in cost.

Get movingThe single most important way to make this project the most cost-effective expansion of the Muni Metro system it can be is to begin construction as soon as possible. The second most important thing is to find a way to extend it to North Beach. The sooner we find the funding to implement these recommendations, the sooner we all can enjoy faster and more reliable transit in the northeast section of San Francisco.END


1 Including vehicle access times from the curbside (stepping onto the bus or walking down to a deep subway station) but not including waiting time. Source: Federal Transit Administration, Central Subway, San Francisco, CA, Preliminary Engineering, November 2006.
2 Ibid.

3 The Municipal Transportation Agency estimates subway construction annual inflation at 6 percent (personal conversation). Overall construction inflation is running as high as 10 percent per year, according to the Engineering News-Record.

About the Authors: 

This report was written by SPUR's Central Subway Task Force.

Chair: Stephen Taber

SPUR lead staff: Dave Snyder