A new report from the American Public Transportation Association (APTA) comes out firmly in support of the belief that correlation proves causation. The report observes that traffic fatality rates are lower in urban areas with high rates of transit ridership, and claims that this proves “that modest increases in public transit mode share can provide disproportionally larger traffic safety benefits.”
Here is one of the charts that APTA claims proves that modest increases in transit ridership will reduce traffic fatalities. Note that, in urban areas with fewer than 25 annual transit trips per capita — which is the vast majority of them — the relationship between transit and traffic fatalities is virtually nil. You can click the image for a larger view or go to APTA’s document from which this chart was taken.
In fact, APTA’s data show no such thing. New York has the nation’s highest per capita transit ridership and a low traffic fatality rate. But there are urban areas with very low ridership rates that had even lower fatality rates in 2012, while there are other urban areas with fairly high ridership rates that also had high fatality rates. APTA claims the correlation between transit and traffic fatalities is a high 0.71, but that’s only when you include New York and a few other large urban areas: among urban areas of 2 million people or less, APTA admits the correlation is a low 0.28. Continue reading
