We've seen this pattern before: there was a lot of misinformation circulating about hybrid DMU trains, which were seen as an alternative to electrification when in fact they do not exist and are not capable of meeting Caltrain's requirement for high-capacity, high-acceleration rolling stock.
There is an off-the-shelf example: Bombardier's ALP-45DP, shown in the photo at right. A small fleet of these beasts operates for commuter agencies in New Jersey and Montréal, Canada, where certain lines are only partially electrified. Rather than inconveniencing passengers with a change of trains where the wire ends, these locomotives fire up a pair of 2,000 horsepower V-12 engines and continue their trip beyond electrified territory.
These make absolutely no sense for Caltrain.
- They are expensive. Two locomotives in one cost almost as much as two locomotives. New Jersey Transit paid $8 million for each one in 2010. Caltrain would require a fleet of about 25. There goes $200 million, nearly half the amount allocated to the new fleet purchase under the electrification project, and none of Caltrain's aging passenger coaches would be replaced.
- They are heavy. These locomotives have the heaviest axle load of any passenger locomotive in the world, at nearly 33 metric tons. Heavy beats up the track and increases maintenance costs.
- They are slow in diesel mode. Even with two 2,000 hp V-12 engines pulling as hard as they can, the million-pound weight of a Caltrain commuter train will hold the train back and limit the trip-time savings of an all-stops peninsula local to just one minute, all else being equal.
- They are slow in electric mode. Imagine that some day the funding finally comes together to string up electric wire along the entire length of the peninsula. The laws of physics being what they are, the power-to-weight ratio and the weight on drivers of a train powered by a dual-mode locomotive does not allow it to accelerate quickly, even if its rated top speed is 100 mph. In stop-and-go service on a local train, an ALP-45DP running in 100% electric mode would only save four minutes on its entire run between San Francisco and San Jose, compared to today's timetable.
The only remote opportunity that dual-mode locomotives might present is the ability to serve the Transbay Transit Center, which is not designed for diesel trains, prior to the full electrification of the peninsula corridor. The San Francisco downtown extension tunnel, however, won't be completed for at least another decade and will cost two to three times more than Caltrain electrification. That's an awfully long time to realize the meager benefits of dual-mode locomotives, on a shaky premise that funding won't be available for Caltrain electrification even after the DTX is paid for in full.
For the peninsula rail corridor, dual-mode locomotives are clearly a proven solution looking for a problem. The better problem to solve is how to fund the electrification project even if the high-speed rail funding is denied.