The problem with buses IMO is the planning - most of the time planners take the cheap way out and just let them use the same road resources as cars. IMO a good

The problem with buses IMO is the planning - most of the time planners take the cheap way out and just let them use the same road resources as cars. IMO a good local transport is completely separate from the roads used by cars, such that congestion on the car road network doesn't affect the second system - i.e. you always get a real alternative. Having one lane for buses, taxis and ambulances would be a pretty good solution, but that's usually not how it works out. Also, you have to look at the whole system in terms of how much surface space it needs - in any reasonably dense city you soon start to need to go either underground or stilted. Railways have a much narrower footprint due to their efficiency - so if you can make them reliable (which is clearly doable, see Japan and Switzerland as examples), it's just a more space saving solution, thus you need to tunnel / stilt less.