>No - subway trains can travel 50 mph or more - a bus can’t do that on city centre roads. If you have really comprehensive coverage in a densely built area you

>No - subway trains can travel 50 mph or more - a bus can’t do that on city centre roads. If you have really comprehensive coverage in a densely built area you'd be stopping too often for those top speeds to matter. This is the problem with the Acela. It can technically go up to 150mph, but it has to stop so often that it averages 60mph for the journey. For longer distances with limited stops, the speed and shigh capacity of a train are good. But to really fill out coverage in a dense area, short wait times and short distances between stops and destinations should be your chief considerations. Buses and streetcars just do that better. Though really, once you get past a certain level of density you need all of the above.