The quick answer is no.

BART requires separate tracks and infrastructure (because it runs on non-standard gauge tracks). To replace Caltrain with BART, all the Caltrain infrastructure would have to be removed and rail service would have to be shut down rail service for years during the construction period. Replacing the entire Caltrain line with BART could cost as much as $20 billion and would take from 30 to 50 years to fund and construct. So it’s out of the question.

Implicit in this question, however, is an assumption that it would be desirable to replace Caltrain with BART, that BART has positive qualities that Caltrain cannot hope to attain. We believe this assumption is based on erroneous impressions.

1. People like that BART runs frequently and somehow think that Caltrain cannot run frequently. Service frequency has more to do with having enough operating funds than technology per se. However, electrification is known to reduce operating costs and thereby allow transit agencies to run more trains at less cost. Caltrain could run just as frequently as BART if there’s enough operating funds to run extra trains.
2. Some people think that Caltrain is slower than BART. This perception was more common before Caltrain began running its “Baby Bullet” express service. In actuality, the average speeds of the two systems are about the same, about 34 mph (including stops), with BART slightly faster. Electrification and signal system upgrades will make Caltrain run even faster.
3. Some people argue that it would be better to have one major rail system for the Bay Area, and this would somehow make it easier for people to take transit. However replacing Caltrain is not the only way nor the best way to make it easier to take transit. Many major cities across the U.S. and the world have a single rail system that have lines that aren’t compatible with each other. The key to make it easier to take transit is to offer common riding experience by making various parts of the system just as convenient. Electrification is one step towards that goal.
4. There are characteristics of the Caltrain system (express service, stop near AT&T Park) that won’t be replicated by a BART replacement. Many trips on Caltrain today would become slower and less convenient if it were to be replaced by BART. It would also put more pressure on Muni to serve current intra-SF BART riders that would get crowded out from BART.

BART is a one-off system that requires custom-made trains that are incompatible with the worldwide standard that Caltrain electrification will follow. This decreases competition to build BART trains and increases BART’s cost.  Caltrain, on the other hand, can operate off-the-shelf equipment produced by a variety of manufacturers worldwide. In fact, some of the nicest amenity-filled high-speed trains in Europe cost less to build than a BART train does.

Recent BART extensions are estimated to cost over $200 million per mile.  By contrast, the total costs for electrifying the existing Caltrain line, enabling it to provide service both faster and more luxurious than BART’s, is between $4 million and $5 million per mile, or about one-40th the cost!

In the end we have to remember that the point is to carry passengers and to provide a good level of service. The major problem with the idea that BART should replace Caltrain is that it has been more of an excuse not to improve Caltrain, rather than any serious intention to fund and build BART. Over the decades, we’ve seen some BART-friendly politicians voted against Caltrain improvements. Caltrain missed many funding opportunities and our region has suffered more traffic congestion and poorer air quality as a result of not doing anything. A principled public official should support whatever that can best help reduce traffic and our environment and not having a particular bias for or against one mode of rail transit based on false perceptions.