Well considering that I haven’t actually plotted the flyover route, you are a little early on the criticism.

As far a San Bruno Canal goes, that could be rerouted, but as I noted earlier, the bigger problem is the support structures for the highway.

Hmm. More and more problems.

Thanks for commenting.

I have some questions for you:

1. How are you planning on handling the differences in loading gauge between BART and Caltrain? Specifically,
   1. BART is high-platform and Caltrain is low-platform – so Caltrain equipment would have to have a different platform than the existing BART platform at SFO;
   2. BART tunnels between Millbrae and just before the bridge over 101 to SFO. The dimensions for BART are too small to permit a Caltrain-sized train to fit.
2. Why are you proposing a solution that imposes continues operating expenses? Why not for example have the tracks dual-gauged so that standard gauge and BART trains could share the same track bed? This happens in many parts of the world where narrow gauge trains share stations with standard gauge trains.
3. I like your idea of reusing the existing BART flyover and suspect that when Caltrain is electrified that it is possible that the load limit for the structure might be reusable. However, I am curious why you would want to perpetuate the poorly designed stub station model? Wouldn’t it be cheaper to simply build a new flyover that allows a run-through station?
4. I agree with your statement about tunneling being expensive and problematic. More on that below.
5. Even with all of this wouldn’t it be easier (and better) if we couldn’t get a direct Caltrain connection to SFO to repurpose the BART infrastructure to be used by the automated people-mover? This would enable more of a direct connection to the airport. If you look at the existing San Bruno station, you can actually see the people-mover which is only about a 1/4 mile away. Routing the people-mover across to the San Bruno station or via the BART flyover/tunnel (which BART would no longer use) to Millbrae is probably also “cheaper” — the loading gauge issues are less dramatic and certainly the load limit issues on the existing flyover are not an issue

Expanding on the tunneling disagreement. I went by SFO after I wrote this blog post. I think that a flyover would be a lot better. So rather than going down — the train should go up. This would avoid problems with managing construction around the support structures for all the highway ramps and the SFO international terminal. A flyover would also enable the existing buildings to the north or south to be more easily managed — no surprises about what is underground, and only the air rights over existing building would need to be condemned.

A less expensive option would be to discontinue BART service to Millbrae, such that that station can be converted to five standard gauge tracks (up from two). The currently underutilized ramp from Millbrae to SFO could be made available to selected Caltrain equipment retrofitted with variable gauge trucks. A gauge change station would allow Caltrain to use BART’s existing broad gauge tracks at SFO. Just add overhead catenaries along the ramp and into SFO plus BART signaling equipment to these special Caltrain consists.

This would imply a new Caltrain service between Gilroy/SJ and SFO alongside the existing one to 4th & King as well as the future service to the Transbay Terminal. HSR trains would not make it into SFO, though – passengers would have to transfer to Caltrain. If BART refuses to host BART-compatible Caltrain equipment at the SFO station, SamTrans could always re-instate its shuttle bus.

See this map for details.