[sparkman55]

Caltrain is already pretty good on the Peninsula. Since the various towns on the Peninsula were founded in the railroad era, the Caltrain stops conveniently in each downtown.

Where would a BART line run on the Peninsula? Down 101 from Millbrae? Such a route would cost billions over some of the most expensive real estate in the country, yet wouldn't serve the denser parts of the peninsula well.

Modernizing the Caltrain seems like a much better use of money. It's clear from the website that this stuff is very expensive!

If we want to dream, a BART extension from Milpitas through Santa Clara (and the new stadium) to link up with the light rail and Caltrain in downtown Mountain View would be awesome, though!

[ak217]

Caltrain is not "already pretty good". It has antiquated, overweight trains due to federal requirements and the fact that it shares track with freight traffic. Those trains can't accelerate properly, so those "convenient" stops in each downtown mean the trains can't run with enough frequency. There are not enough trains and too many at grade crossings, which produce severe noise pollution (due to the federal horn sounding requirements).

Caltrain is WAY overdue for upgrades. The electrification project, which will solve some but not all of these problems, is in need of a speedup. Many at grade crossings need to be replaced with bridges (and some are being replaced), but because of all the fiefdom-like towns along the way, getting anything done along the right-of-way is a nightmare.

Although there is no tractable way to merge Caltrain with BART (because of BART's own foolish planning decisions, such as a custom gauge), and you're right that there is no space for a second right-of-way, there is another neglected project that would benefit here: Dumbarton Rail (http://www.bayrailalliance.org/dumbarton_rail). At various points it was suggested that either BART or Caltrain should be extended across that bridge - either way, completing that link would add badly needed capacity in a region that has long neglected its traffic infrastructure.

[ghshephard]

Caltrain is far from "pretty good" on the peninsula. It's passable for a few purposes only - commuter and event rail. (I.E. Getting people to the office in the morning, getting people people home at night, and likewise with sports events in AT&T stadium).

As a serviceable mass transit system, it's almost worthless. The trains come infrequently, and require really inefficient transfers in the city to BART if you want to travel from, say, Mountain View to Oakland.

I just came back from Singapore - and I was able to get almost any place in the country + a 5 minute cab ride the entire day using their MRT. I understand that Tokyo (and to some degree, New York) have similarly advanced transit systems.

I used Caltrain + Bart for about 15 years, but you really don't realize how bad Caltrain + BART are, until you travel somewhere that was a first class mass transit system.