Vision Zero, Meet VMT Reductions

Todd Littman, Planetizen

Many jurisdictions have vehicle miles traveled (VMT) reduction targets, intended to reduce congestion and pollution. They can also provide large but often overlooked traffic safety benefits.

Many jurisdictions are officially committed to Vision Zero, an ambitious goal to eliminate all traffic deaths and severe injuries. Although some cities are making progress, most jurisdictions are failing. U.S. traffic death rates declined during the last half of the the 20th century, reaching a low of 32,479 in 2014, but subsequently increased, averaging about 37,000 annual deaths during each of the last three years. New strategies are needed to achieve ambitious safety goals.

Several new strategies exist, and are overall very cost effective, considering their total benefits, but are generally overlooked in conventional traffic safety planning. Conventional traffic safety programs tend to assume that motor vehicle travel is overall safe, and so favor targeted strategies that reduce higher-risk driving, such as graduated licenses, senior driver tests, and anti-impaired driving campaigns.

However, such programs generally fail because it is not feasible to reduce high-risk driving alone. It is infeasible for most teenagers, seniors and drinkers to significantly reduce their driving in sprawled, automobile-dependent areas that lack non-auto travel options. Every time we tell somebody to reduce their high-risk driving, we have an obligation to create more accessible and multi-modal communities so they have viable alternatives.

Although the United States has rigorous road and vehicle safety standards, and numerous traffic safety programs, it also has the highest per capita traffic death rate among developed countries. Why? Because people in the United States also drive more than residents in peer countries . . . .

An abundance of research, described in the World Resources Institute report, “Sustainable & Safe: A Vision and Guidance for Zero Road Deaths,” and in my report, “A New Traffic Safety Paradigm,” indicates that, all else being equal, increases in motor vehicle travel increase crashes, and vehicle travel reductions increase safety.

In other words, the new traffic safety paradigm recognizes exposure, the amount that people drive, as a risk factor. Since about 70% of casualty crashes involve multiple vehicles, so vehicle travel reductions provide proportionately large crash reductions. For example, if you reduce your mileage by 10%, your chance of being in a crash declines by 10%, but there is also a reduction in risk to other road users, since your vehicle is no longer vulnerable to other drivers’ errors.

This means that we can increase safety by either reducing per-mile casualty rates through road and vehicle design improvement, and policies that reduce high-risk driving, and by reducing total vehicle travel which reduces total risk exposure. The old safety paradigm only considers the first approach. the new paradigm recognizes both approaches. The table below compares the old and new traffic safety paradigms.