From Albuquerque Residents For Modern Streetcar
Note: The following applies to all modern urban Rail, not just streetcars.
Attracting riders: As shown in numerous studies, rail transit increases the number of people who will use public transit. A streetcar line attracts new riders who otherwise would not ride a bus. This wider “spectrum” of ridership generates greater public support for transit.
Quality of Service: Streetcars are more comfortable than buses. The vehicles are much more spacious, the ride is smoother because the rails are embedded in the street, and the vehicles tend to be much quieter as streetcars run on electricity rather than diesel.
Capacity: A streetcar can hold many more passengers than a bus (nearly 3x the capacity of a regular bus!). The number of buses required to equal the capacity of one streetcar makes buses more expensive to operate and maintain per passenger mile. The higher capacity of streetcars also makes them more energy efficient than buses.
Accessibility: Modern streetcars are low-floor vehicles, which means that the floor of the streetcar is nearly level with that of the station platform (in this case, the sidewalk). A small automatic ramp allows for easy and quick access for disabled passengers and strollers. It is also easier for bicyclists, since the interior layout is designed so that bicycles can be brought on board.
Environment: Streetcars run on electricity, so they do not give off exhaust emissions at point of use and are easily adaptable to renewable resources, like solar or wind power (for instance, in Calgary, Alberta their light rail system runs entirely on wind-generated electricity). Streetcars also have steel wheels instead of rubber tires, which tires emit poison dust while in use, and are very difficult to get rid of. *
Sensible Development: Streetcars also encourage high density, pedestrian-friendly development, creating an alternative to endless auto-dependent sprawl.
Economic growth: As seen in cities across the country, the construction of a streetcar or light rail line generates millions of dollars in private development and supports long-term economic growth. The fixed nature of a rail line (it can’t just pick up and move like a bus route can) channels development along the streetcar line, increasing density and creating pedestrian and transit friendly development.
* See Where Does Tread Rubber Go? by Peggy J. Fisher and Tyre Dust by Pat Thomas with The Ecologist for some insight into the issue of tire dust. Concerning tire disposal, there’s the Wikipedia article on tire recycling as well as the disaster of Osbourne Reef.