It is difficult to answer this question because there seem to be as many “environmental arguments” as there are environmentalists, some of whom I count as my friends. And I am grateful to them for their role in ridding London and other cities of the soot in which they (the cities) used to be covered, and, more importantly, of the associated life-shortening diseases.

On the other hand, how does one deal with those (e.g. in the EPA) who consider any environmental benefit, however small, worth any cost, however large? Or those who promote “blood for oil”, by advocating the downsizing of vehicles at the cost of thousands of additional fatalities on US roads? Or those responsible for millions of avoidable deaths from Malaria because of objections to DDT? Do not some environmentalists practice what seems to be a dangerous religion, complete with its human sacrifices?

Yes, as David Pickeral points out, reduced traffic congestion can improve the environment. But should not those who sup with environmentalists use long spoons?

Data collected by industry, government and academia over the past several decades shows a clear correlation between a modal shift from personal vehicle to public transit use and positive environmental benefits in two very distinct ways. Reducing emission sources – such as a typical 40-foot transit bus that could replace dozens of private vehicles even if they are filled to capacity or a light rail vehicle or a commuter train that could take hundreds of cars off the road – is dramatic in terms of CO2 reductions. Because traffic is reduced due to the move to public transit, the flow of the remaining vehicles on the highway becomes more efficient and reduced congestion lowers the carbon footprint of these vehicles. The reduced energy use caused on the demand side by such efficiency has additional environmental benefits on the supply side by lowering the environmental impact of energy production and distribution. Transit is a win-win situation when it comes to both the environment and the public.

Even though there is growing public interest in using mass transit, it is important to provide practical incentives through clear and accurate real-time information that allows commuters to make the shift to mass transit from their own vehicles as seamless and easy as possible. Weather, maintenance work, incidents and events each play a role in how different modes of transportation operate so access to transit information helps citizens make more informed immediate and long-term choices. The end result will be a balanced optimization of transit use and personal vehicles that can result in a faster commute and many environmental benefits.