>Probably doesn't work in some urban sprawl American suburb
yep, hi. It's also the same kind of area where road maintenance is the highest problem. Lot's of road wear and tear, and not enough funding to maintain properly
Light rail has a lot more destinations, and most rail systems are designed to complement bus systems.
I live in Utah, and our "urban" area (SLC) is similar to many "suburban" areas in terms of population density. We have a commuter line that intersects with light rail, which intersects with the bus system. Rail hits most of the important business areas, and buses hit most of the residential areas, and each runs every 15-20 minutes. If you know the system, you can get around fairly well without a car. It was expensive to build, but it is used quite a bit so it is absolutely worth it.
Depends on the average traffic speed. Subways go over 60mph and are generally the fastest vehicles in a large city besides helicopters and airplanes, and lane splitting motorcycles.
Probably doesn't work in some urban sprawl American suburb but for more sensible layouts its the best option. Also the best for the environment.