With President Barack Obama promising to spend billions of dollars on economic stimulus projects, and Congress taking up the re-authorization of the transportation bill this year, several U.S. cities will be making important infrastructure choices that will have lasting consequences for their emissions and traffic.
"There are a lot of cities that are thinking very grand about their transit plans," said Andrew Seth, deputy director of the group Climate Communities. Expensive construction projects that are sure to ignite years of planning battles might not be the best move, though. Many cities should instead try looking south—far south—to where Latin American metropolises have bypassed Byzantine planning debates and the massive troubles associated with implementing or expanding metro rail services. Instead, they have reinvented older and lower-tech solutions—trolleys and rapid bus systems.
Metro systems are economically and emission-efficient in the long run, but in the short-run, their capital costs are tremendous. Subway lines typically cost well over $100 million per mile to build. New York's struggle to update its subway system are legendary. The city's 2nd Avenue subway line has been in various stages of planning, funding, or construction for 80 years.
In comparison, variations on above-ground light-rail systems and trolley-buses—bus carriages linked to electrified overhead wires—cost around $3 million per mile; certain types of bus installations can cost as little as $125,000 per mile. It's clear what's cheap, and what's not.
With that knowledge, some relatively poor Latin American cities have leapfrogged the piece-meal approaches American cities have taken to constructing mass-transit infrastructure—often because there wasn't enough "funding to put in place the next generation of transit," Seth said—and built full-scale, above-ground systems instead.
The most impressive model is Bogota, Colombia's TransMilenio, a bus-rapid-transport system that has a daily ridership topping out close to 1.5 million. In 2006, it became the first mass transit system in the world to be certified as a clean development mechanism (CDM) by the U.N. Framework Convention on Climate Change in accordance with the Kyoto Protocol. The system has reduced emissions in the city by an estimated 250,000 tons of CO2 per year, a number that is expected to increase as more-efficient buses replace older models.
Bogota was also able to secure far more system for its investment with the TransMilenio. The city originally considered building an 18-mile heavy rail line, but it balked at the rail line's $169 million cost per mile, more than 10 times the cost per mile for the TransMilenio. For about the same overall price as 18-mile rail line, the TransMilenio gave Bogota a 241-mile-long citywide system. Passenger surveys conducted since the system went into operation in 2000 typically find that about 75 percent of the riders are pleased with the system.
The TransMilenio was inspired by Curitiba, Brazil's Bus Rapid Transit (BRT) system. There, bus stations are enclosed, tube-shaped structures, and passengers pay as they enter. Precise percentages vary, but some 75 percent of trips within the city reportedly use this system—close to 1.5 million boardings a day.
Quito, Ecuador, situated in a North-South oriented mountain valley, uses bus-trolley hybrids, operating as conduits in dedicated lanes that parallel the valley's orientation. The city's Ecovía and Trole systems are hydropower-based and emissions-free. Before the implementation of these systems, riders relied on antiquated buses that belched pollutant-heavy smoke. World Bank research estimates that the Quito system's average daily ridership at 170,000 per weekday in a population of around 1.8 million.
The relevant comparison is the differences between metro systems, light-rail (or trolley-bus) systems, and BRT systems. Exploratory studies suggest that given the realities of current electrical generation systems, low-emissions diesel or hybrid BRT systems are the best bet, at least in the short term.
Further in the future, with a clean grid producing the energy, a light-rail system clearly gets the better of a bus system. Buses also reach saturation points quicker—Curitiba is attempting to add a monorail or metro to the densely packed spine of its transit system.
Planning experts, take note.