BART’s Oncoming Transbay Capacity Crunch


BART’s  ridership is projected to rise from its current level of over 400,000 riders a day to 700,000 riders a day or more by 2040.  This increase will severely overtax BART’s transbay section, which already often operates at peak carrying capacity.  As a result BART is in already the process of removng seats and otherwise preparing for substantially more crowding on its trains.  But despite these measures, BART will reportedly run out of transbay carring-capacity around 2030, at which point the lack of an adequate transbay connection between Oakland and San Francisco will begin to constrain the economy of the Central Bay Area.

Bay Area transportation officials do not appear to be concerned over this impending transbay crunch.  “Don’t concern yourselves”, they say: “things will work out”.  Some say another rail tube will solve the problem.  (Sure…in 4 or 5 decades, assuming the availability of the $25 – $35 billion needed to build another subaqueous rail tube complete with connecting subways).  Others say that AC Transit will fill the need.  (For this to happen AC Transit’s transbay ridership would have to increase by at least 700%,  from the current 14,000 transbay riders a day to 100,000 or more riders a day).

This oncoming transbay passenger rail constraint is a serious regional problem that is not getting the attention it deserves.  On the contrary today’s regional and CMA planners continue to focus on creating more city traffic by expanding surburban highways, extending BART into outlying suburban areas of low potential ridership and otherwise looking at everything but the Region’s biggest oncoming problems.

In recent weeks there has been increasing talk about building a second BART tube under the Bay.  However so far no one has mentioned cost.  As things stand it appears that the oncoming transbay capacity crunch will arrive decades before a second BART connection can be funded, designed built and put on line.



  1. Dear Marilou,

    As you indicated, the impending BART capacity crunch is a threat to the future commercial viability of the Central Bay Area. People talk about a second passenger rail tube under the Bay, but no one discusses its multi-billion cost (with connecting subways on both sides of the Bay, estimated to be in the $20 to $25 billion range) or the four or five decades it would take to get so large and complex an infrastructure project up and running. The Bay Area is growing in both population and employment and is expected by ABAG to continue to do so. For this reason the inadequacy of transbay rail service will begin to constrain things long before the advent of a second transbay rail crossing. It is therefore imperative that intermediate steps be taken.

  2. More on the Transbay BART crunch: There are some intermediate steps that could and should be taken to soften the blow. First it will be necessary to greatly increase AC Transit’s transbay bus ridership. AC Transit’s 29 separate transbay lines currently carry an anemic total of only 15,000 riders a day, just 7% of what BART carries. AC Transit can do much better. It needs to immediately institute a transbay bus improvement program that incorporates improved routes, in some cases combined routes (to allow buses to come more frequently), transit-only lanes where necessary to assure consistently reliable and expeditious service, added interior features such as comfortable seats and wi fi, and better mapping and marketing.

    Another intermediate step that should be considered is reestablishing passenger rail service across a rebuilt Dumbarton rail bridge between between Fremont and Redwood City. From Redwood City, trains from the East Bay would use existing Caltrain tracks to access San Francisco.

    Addressing this problem will require the Region to look at short and intermediate range solutions as well as longer range solutions.

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