wilber1 wrote:
According to the Federal Highways Administration the average diesel transit bus gets 3 MPG. Unless they are running on routes with a high load factor, they have quite a large emissions footprint per passenger carried. Add to that, all the other maintenance and fluid/filter disposal issues you have with ICE's. Trying to electrify public transit as much as possible makes a lot of sense.
You can find numbers all over the place. Lots of variables. Numbers I've seen used by transit agencies is typically 6-8mpg. With a moderate 10 passenger average, that's 60-80 passenger miles per gallon.
Considering your average commuter car has 1.1 passengers on average and around 30mpg. The equivalent is 33 passenger miles per gallon. Even most high MPG cars will struggle to beat the bus.
Of course, bus size should be matched to load factors. If you rarely get more than 20 passengers, you can always drop down to a smaller bus that will get better MPG.
Usually the assumption is a hybrid city bus will get 30-50% better MPG but again, it depends a lot on route and driving style. Ironically, the worst routes get the biggest improvements. Big improvements in emissions are to be had. No clouds of black smoke when they accelerate away from a stop.
Pure electric fits with the link in the other post. A few specialty uses but no large scale implementation.