What I observed was simple. The trains run about 50 mph on dedicated rights of way and along freeways. On streets, they tend to cruise about 30 to 35 mph. In both situations, they tend to go slower than autos in off-peak hours, and faster than autos in rush hour. When I rode trains at 2 p.m., autos on adjacent streets or highways passed me.
Trains work best at the times large numbers of people are moving.
Streets and highways are the opposite. They are at their worst when large numbers of people are moving. These are rather simple lessons, but ones that are hard to understand unless you ride the rails. Altogether, they explain why people ride trains but not buses. That's like going to a surgeon and asking whether bypass surgery is good or bad.