If it is travelling on a precise guideway (more precisely aligned than a traffic lane), then it is possible to transfer electrical power to it safely, either by aligning a pantograph with an overhead catenary or by a system of conductive rails, Once you can do that, the vehicle’s weight drops (as it doesn’t need to carry as much fuel), increasing carrying capacity and/or reducing the frequency of required road maintenance, Additionally, as electrical power is fungible (and can be sourced from whatever generation method is most economical), running costs are decreased over combustible fuel (as long as you don’t need to store it in the vehicle).

The obahn in Adelaide is elevated, near a river. Not often near other roads for emergency vehicles so would be of limited use for that. The bus has small horizontal wheels that keep it on the tracks, and allow it to go reasonably fast, about 80 km/hr between stops. Once it gets closer to the city, it does just use dedicated bus lanes, that emergency vehicles can also use. It's not perfect, but works pretty well and at morning rush hour I can catch a bus every minute or so from my stop. Most of the buses are pretty full, so that's a lot of cars off the road. Once the buses are full electric I think it will be even better and quieter.