The need for a second Transbay rail crossing to augment the existing BART tube across San Francisco Bay is painfully clear. Beyond relief for overcrowded BART trains, the second tube is required to shift auto trips onto transit and reduce greenhouse gases, create resiliency in the transit network, and enable continued regional growth sustainably, among other objectives.
Instead of BART, what if the second tube was built with standard gauge tracks, from the Transbay Transit Center to downtown Oakland? This would enable the eastward extension of electrified Caltrain, as well as other standard gauge railroads such as High Speed Rail and an electrified Capitol Corridor. The standard gauge tunnel would not preclude access from the East Bay BART lines if it included a convenient cross-platform timed transfer in Oakland. In fact, a standard gauge tube would provide the same capacity and redundancy benefits to the Transbay corridor as a second BART tube – but at far less cost.
In addition to cost-effectively addressing the Transbay corridor, this convenient BART/Caltrain transfer would benefit the entire Bay Area by finally linking the two regional rail agencies – via a new station in the I-980 trench in Oakland, reuniting West Oakland with downtown with new development opportunity. This connection would be so seamless that the passenger would not perceive two separate rail agencies, but instead a united Bay Area rail service: CalBART.