Comment by osdiab
9 years ago
While I generally agree with what you're saying about embracing bus rapid transit and the cost effectiveness of that option, it's not 100% just a matter of congestion. Surface rail often reduces the value of the land around it due to noise, poor streetscape, etc. whereas subways typically dramatically increase the value of the land around it and don't disrupt the neighborhood. Same goes for large surface roadways.
Also, buses don't have the same capacity as rail does—it's difficult to string together 10 buses and still accelerate quickly, navigate turns, and deal with grade crossings with street vehicles (although guided buses maybe can get partway there? [1]). You can feel the burn in the Bay Area if you try riding the lines on Geary or Mission during hot hours.
And the speeds at which buses run within dense metros often cannot compete with modern subway trains—BART, which is an old system already, hits 70 mph and can go faster, which would be kinda scary to do on city streets in a bus.
I'm not convinced that buses don't have the capacity trains do, when you consider that headway between trains is at least 90 seconds. If headway between buses is three seconds, in those 90 seconds, 30 buses can pass by. Assuming a bus has roughly the same capacity as a coach in a train, and that the train has 8 coaches, buses have roughly 4x the capacity.
Not to mention that buses can serve many routes that don't have enough capacity to merit a train, bus routes can be reconfigured without it taking years, and a bus system doesn't cost billions upon billions of dollars to build. Heck, even a single line of a metro system can cost a billion dollars to build.
If buses have dedicated panes where they don't have to interact with normal traffic they can easily hit 70mph. Australian highways in certain places have this system.
My favorite is Vancouver skytrain. While building highways they built a train track on pillars. It's fast and usually got me in and out of the city quicker than a car.
I imagine train tracks on pillars cost effective than underground tunnels. For a dense city it makes sense. Not for outskirts.