The power of public transit

One small mile for a passenger, 10 fewer giant miles for vehiclekind

Sometimes we underestimate how much public transit can reduce driving and generation of global-warming gases.

New transit systems are frequently built to reduce commute congestion, and it is assumed that every new passenger takes one car off the road for that trip length: one passenger-mile on transit reduces one vehicle-mile in a car. But studies in the Bay Area and elsewhere show that one passenger-mile on transit can reduce driving by 8 - 10 vehicle miles traveled or more.

How is that possible? Good transit facilitates development of extremely convenient communities, where shopping, jobs, recreation, and friends are close to home, making trips short and allowing many to be made by walking, biking, or a short transit trip. These dense mixed-use communities with attractive walking environments are made possible by the availability of public transit for necessary longer trips. Let's look at the conditions that achieve these reductions in driving.

First, there must be enough density locally and nearby to present a wealth of destinations - dense, but not necessarily crowded. In grad school, I found Los Angeles terribly crowded, confining and claustrophobic. But my current neighborhood, in the Russian-Nob Hill-Chinatown-North Beach area of San Francisco, has 10 times the density yet is not crowded at all. While that may seem illogical, it isn't. We generally think of two types of "crowded": your home is crowded if too many people live there, and the roads are too crowded if you can't move freely. Well, few of my neighbors' homes are too crowded; mine isn't. And since I got rid of my car and walk everywhere, my "roads" aren't congested, unless you call elbowing your way into busy sidewalk produce markets in Chinatown crowded. I don't. I call it urban adventure, and people pay good money to visit San Francisco for that.

Second, locate jobs, markets, restaurants, video rentals, etc. near homes. Within an easy and inviting one-mile walk of my home in San Francisco, I have over 700 restaurants and probably as many food markets. In my neighborhood many of these are mom-and-pop operations on residential streets. In less dense neighborhoods these businesses could be restricted to major streets - but still in the neighborhood, not stuck off in a shopping center five miles away, accessible only by freeway.

Third, build pedestrian-friendly walkways and streets, including:

• an efficient pedestrian street grid not broken by dead ends, freeways and drainage ditches (a rectilinear street grid offers many alternative paths, allowing the walker to explore different streets, find favorites, and link trips more easily; winding streets, intersected by dead-ends and cul de sacs, require longer trips and allow no such variety);
• sidewalks, with bus shelters; occasional seating and other sidewalk furniture; trees, awnings, and weather protection; and fountains, interesting store windows and other attractions;
• building entrances near sidewalks so that they don't require pedestrians to walk through parked cars or tread a long path;
• safe, slow, careful traffic, with drivers alert for pedestrians and children, not drivers intent on getting through the area speedily; or at least sidewalks protected from traffic, with frequent stop signs and lights to allow safe street crossing.

These neighborhoods convey a sense of being somewhere, rather than a place to pass through. Since autos are given less land, more is available for natural habitats, creeks, and wildlife corridors.

Then provide good public transportation for those with limited walking range and for the longer trips that are sometimes necessary for everyone.

Under these conditions, trips are shorter; more are walked or biked; and the miles on transit reduce driving by a much larger factor (called transit leverage) than in sprawl areas. The transit leverage for those living in North Beach, compared to living in a sprawling area like San Ramon, is perhaps 20. That makes public transit a real global-warming dragon slayer in convenient communities.

For a more detailed presentation of this analysis, visit www.sierraclub.org/sprawl/articles/reducedriving.asp

John Holtzclaw, member of Sierra Club national Building Healthy Communities and Global Warming/Energy Committees