Recently there has been much discussion regarding the environmental sustainability of automobiles versus transit. Stephen Dubner of Freakonomics Radio, interviews Eric Morris, a planning professor, who suggests that driving an automobile is friendlier to the environment than riding transit.
A SEPTA Hybrid Bus
Their argument rests on the (faulty) assumption that although single occupancy automobiles have high emissions, most buses do not run at full capacity and as such, emit more pollution per person than automobiles.
A 2009 EPA report shows that when buses carry an average of 11 people (most people have seats for 40 people), they are more fuel-efficient than automobiles; a full bus is nearly four times as efficient.
This discussion asks the question, “What is the most sustainable form of transportation?” In the book, Sustainable Energy – Without the Hot Air, David JC MacKay compares multiple modes of transportation by the energy needed to travel 100 kilometers.
Emissions per Vehicle Comparison Chart
This research shows that buses are more efficient that single occupancy cars and a full car is more efficient than a bus. However, trolleys, subways, electric and diesel trains, and trams are more efficient than a full car. The most sustainable forms of transportation are walking and bicycling.
In Philadelphia, 9.2% of people walk to work, and 2.5% use bicycles. Furthermore, the recent Complete Streets Policies approved by the City Streets & Services Committee promotes the use of transit, walking, and biking, works towards more sustainable transportation of the entire City.
Want to know more?
Streets Blog Network Article
Freakonomics Marketplace Article
Sustainable Energy – Without the Hot Air