I have been talking about these synergies with planes more than with trains though, because of how short most train trips are, notably urban trains. It gets better if you can do just-in-time coordination.
The problem comes, with urban train trips of under 10 miles, of comparing a trip where you go 1 mile to the train, then N miles on the train, then 1 mile from the train to your destination with just staying in the car. Instead of 12 miles with 2 mode changes (even if done very well, which I think they eventually can be) you have a direct trip in the car. It costs a bit more, but it’s still door to door with no parking hassle.
And we know what the public’s answer to this question is. They overwhelmingly own and take cars on these trips. Transit has a tiny fraction of the travel in the USA, and while its fraction of commute miles is larger it’s still overall quite small. And that’s when cars have the hassles of parking and driving. The only advantage the train gets is a possibly slightly lower cost — a cost that clearly does not mean that much to most commuters — and the possibility of a shorter trip due to the dedicated ROW. Gone is the train’s advantage that you can read on the train.
That’s challenging, because in spite of congestion, the travel times of trains are usually not much shorter (especially on the door to door time) and if they are, it’s only at rush hour. I sometimes would ride the N-Judah from our house in the Sunset (which was only 1 block from Judah) to downtown. 30 minutes that takes. It’s decent and cheap at rush hour, especially with parking downtown being what it is. But come 7pm, it was an 11 minute drive and no way I would take the train. I expect the robocars to make that worse for the train.
Alas, mass transit is not efficient even in the dense urban areas outside of rush hour. It is not energy efficient — green cars do much better — and when traffic is off-peak it is not especially road efficient and certainly not time efficient. That’s transit’s problem — great at rush hour, moves a lot of people for reasonable energy and reasonable road space. But then it has to run all day when it’s horribly inefficient, resulting in an inefficient overall performance. BART, New York MTA, Boston T — none of them beat two people in a good electric car. In fact, they are pretty close to a solo driver. Forget SF Muni — it’s worse than the average gasoline car.
No, the peak driving time is lunch hour. I believe the peak transit times are the rush hours. I will need to look at the load numbers but my understanding is that rush hour is “standing room only” and non-peaks are much more relaxed. It has to be for the averages to be so poor — 9 passenger per bus on average, 23 per train car, in the USA.
Yes, commuter rail’s ROW is a big attraction for it. The reason commuter rail is so efficient is that many of them are very rush hour oriented and run mostly full trains. The most efficient commuter rail routes are the ones that are rush hour only and so long that trains do only one run, and wait in the city to come back out, and wait overnight in the burbs. No empty trains at all. These are attractive in places with high road congestion and they offer the commuter the chance to relax and read. Outside of NYC, where transit is most popular, they are the transit that rich people ride. But you have to be a 9 to 5er to ride these sorts of lines.