>>1429052BRT can be done successfully. See Brisbane's Busways. They have high frequency along fixed busy corridors, then the individual routes span out into the sprawl that is south east queensland. It is a system that works quite well, can travel just as fast as suburban trains, but its major drawback is capacity.
A rail line will carry more people per hour effectively, but a busway can allow a large number of suburban bus routes to converge and split and provide a high trunk frequency. This also means the transition from feeder to trunk routes is seamless, unless catching a bus to a railway station. But then that trunk will have less capacity.
Finally, if growth in the system is to be obtained long term, the trunk busway will become too congested. See the congestion at Cultural Centre Busway Station at peak hour in Brisbane. So by building a busway, and then seeing growth in patronage, you may outgrow the capacity of the system, and then have to throw the whole busway out. But the busway is still an effective means of transport for a town or city with modest growth potential that will not need a full rail service.
