Don't have a rail corridor handy? Don't build light rail. By the time congestion is bad enough for a metropolis to think about light rail, land costs are too high for any 'greenfield' corridor, and using existing right of way is the only feasible way.
If the only existing right of way is public street, why spend the money to build a electrified railway? Electrified traction has undeniable perks over rubber-tired buses (fuel costs, acceleration, comfort), but the cost is rarely worth the marginal benefit.
Neither ride comfort nor transit signal priority (TSP) nor dedicated/reserved guideway are specific to rail. Nor level boarding or off-board fare collection. With double-articulated buses, the rider capacity/driver ratio rail previously offered over bus has largely evaporated.
So why do places like Portland keep building light rail? I suggest an availability heuristic: They have lots of old freight rail lines to convert to light rail. I seen symptoms of the same disease in Utah, and efforts to bring light rail to Utah County.
The only actual advantage of rail over bus is political: its easier for a metro to create rail rapid transit than bus rapid transit. In the public imagination, light rail vehicles are like freight trains, whose necessary separation from cars is implicitly accepted.
It is the separation from cars that the true virtues of rapid transit emerge - speed, safety and reliability. Rapid transit requires exclusive/dedicated guide way--exceptions generate accidents reliably, whether in travel lanes or turning lanes.
So it's politically feasible for a light rail to claim a lane a lane on a congested arterial in a way no mere bus could ever attempt. That said, double-articulated buses seem to be able to make some of the same claims to exceptionalism and necessary special accommodations.
If the only existing right of way is public street, why spend the money to build a electrified railway? Electrified traction has undeniable perks over rubber-tired buses (fuel costs, acceleration, comfort), but the cost is rarely worth the marginal benefit.
Neither ride comfort nor transit signal priority (TSP) nor dedicated/reserved guideway are specific to rail. Nor level boarding or off-board fare collection. With double-articulated buses, the rider capacity/driver ratio rail previously offered over bus has largely evaporated.
So why do places like Portland keep building light rail? I suggest an availability heuristic: They have lots of old freight rail lines to convert to light rail. I seen symptoms of the same disease in Utah, and efforts to bring light rail to Utah County.
The only actual advantage of rail over bus is political: its easier for a metro to create rail rapid transit than bus rapid transit. In the public imagination, light rail vehicles are like freight trains, whose necessary separation from cars is implicitly accepted.
It is the separation from cars that the true virtues of rapid transit emerge - speed, safety and reliability. Rapid transit requires exclusive/dedicated guide way--exceptions generate accidents reliably, whether in travel lanes or turning lanes.
So it's politically feasible for a light rail to claim a lane a lane on a congested arterial in a way no mere bus could ever attempt. That said, double-articulated buses seem to be able to make some of the same claims to exceptionalism and necessary special accommodations.
No comments:
Post a Comment
And your thoughts on the matter?