OnEarthBy LAUREN GRAVITZ, OnEarth magazine

Almost half the land area of the city of Los Angeles is located in the San Fernando Valley, better known as simply "the Valley." With 224 square miles and 1.76 million people, the portion of the valley that lies within the city limits would be the nation's sixth most-populous city, just ahead of Philadelphia, if it were a municipality unto itself. It wasn't until 2000 that rapid transit began serving the region, and in 2005, when Los Angeles chose to open a new transit line in the valley, it didn't build a train or a trolley or a subway. It added a busway, the Orange Line, and people here love it.


The Orange Line doesn't look or operate like a regular city bus. The vehicles sport sleek, bullet-train silhouettes and shiny silver paint, and they run along a path that is separated from street traffic by barriers and trees — much like train tracks — and from which all other vehicles are barred. The trainlike features don't end there: outdoor stations have ticket vending machines, bike racks and enclosed bike lockers, and illuminated signs that alert riders to the arrival time of the next bus. Between some stations the buses reach speeds of up to 55 miles per hour — much faster than the cars inching along Highway 101 at rush hour. Special sensors in the roadway detect moving buses and switch street signals up ahead, halting cross traffic so buses can pass through without stopping. Just like the train.

This system, known as bus rapid transit, has begun to emerge as an appealing alternative to trains in many metropolitan regions: it's more flexible, cheaper, and in some cases more environmentally friendly than building a new rail-based mass transit system.

Los Angeles opted for a busway because it offered comparable benefits to an aboveground rail line, at one-third the price, and could be built in half the time it would take to lay tracks and launch rail-based service. And unlike the train, the bus has the ability to leave its dedicated roadway and make stops on regular city streets, delivering riders to destinations they could not otherwise reach by mass transit.

High-speed transportation of choice

The idea has held sway in other cities around the world for many years. High-speed busways augment rail-based transit in Mexico City, where buses move as many as 315,000 people a day. In Brisbane, Australia, a city of nearly 2 million people, bus rapid transit services have a daily ridership of 93,000. In Beijing, Bogotá, Colombia, and Curitiba in Brazil, buses are the high-speed transportation method of choice.

The success of bus rapid transit as a 21st century transportation alternative in the United States will depend in part on efforts to dispel the image of the bus as a poor man's conveyance. Los Angeles, because of the Orange Line's trainlike features, has made progress. In a survey conducted by city transit officials in 2009, riders rated their busway experience as comparable to that of a new light-rail line elsewhere in the city.

That's music to the ears of Martin Wachs, director of the Transportation, Space, and Technology Program at the Rand Corporation, a nonprofit think tank headquartered in Santa Monica, Calif. "We want to get people into public transportation — we want to make it more attractive," he says.

Transportation officials in Cleveland agree. "Bus rapid transit is probably the hottest public transit product on the market today," says Joe Calabrese, the CEO and general manager of the Greater Cleveland Regional Transit Authority, which operates perhaps the sleekest bus rapid transit system in the United States.

Cleveland overcame the bus's poor-man's image by building glass-enclosed stations and designing vehicles that feel like train cars. For instance, their doors open on both sides and allow platform-level entry for easier boarding. The buses run for 6.8 miles along Euclid Avenue, serving many of the city's medical, cultural and educational institutions. The so-called HealthLine has also attracted new businesses to areas where passengers get on and off, adding an estimated $4.3 billion to the local economy. The benefits of bus rapid transit came with a sticker price of $200 million, relatively low compared with other options that would cover the same distance, such as a $650 million light-rail system and a $1 billion subway line.

Bus not always the answer

But bus rapid transit's more affordable price tag could not win over transportation officials in Maryland, who were looking to expand connecting service to the Washington, D.C., Metro system. They opted for rail over bus, despite cost estimates and environmental studies that came out in the bus's favor.

The World Resources Institute, a nonprofit research group based in Washington, D.C., conducted a cost-benefit analysis of the greenhouse gas emissions that would result from light rail and the bus rapid transit alternative. A train's emissions depend on the source of the grid power used to run electrified cars. In western Maryland, that's coal-fired power plants, making hybrid-electric and natural gas–powered buses the lower-emission choice. People tend to forget that "the train isn't emitting, but the power plant is," says Dario Hidalgo, a transportation engineer at the institute.

Though the rail system will cost $1.5 billion — nearly three times the low-end estimate for the bus — state officials argue that the train will allow them to serve a large ridership (projected 65,000 daily) without service delays.

Wachs argues that there is no single factor that determines whether buses or trains are the better option. The bus can be upgraded to accommodate higher passenger volumes by making vehicles longer and requiring riders to purchase tickets in advance to facilitate on-time departures. "It's not like there is a rule, one is better, one is worse," he says. "There's a big fuzzy area. That's what makes it interesting."

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Lauren Gravitz wrote this article for OnEarth Magazine. She writes about science, health and the environment for Discover and the Economist. She lives in Los Angeles.