The New York Times this morning had an interesting story — the third in a series about stopgap measures that could limit global warming — about Bus Rapid Transit lines.

BRT lines are wide, sealed-off lanes dedicated to large buses, but like subway trains, the vehicles only stop at stations with faregates. Where they have been most successful, as in Bogotá, Colombia, they are essentially above-ground subway systems, built at 1/30th the cost of traditional subway lines.

The last time I was in Mexico City, I went on foot over to a segment of Avenida Insurgentes, the city’s major north-south avenue, and got to see a BRT line up close and in action. It appears to work just as advertised.

Although the city has a world-class subway system, there was no line specifically serving Insurgentes. What did serve the avenue was about 400 small, pollution-belching buses. The new BRT line connects with the existing subway system along the central portion of the avenue, and replaced the older buses with 200 larger, cleaner buses, helping to save both the environment and commute times.