In the past couple of weeks a couple of claims have been made by insurance industry officials arguing that bans on texting and cell phone use while driving may be ineffective because traffic fatalities haven't dropped. US Secretary of Transportation Ray LaHood strongly disagrees here and makes many worthwhile points. (Links to the insurance industry arguments are available from LaHood's Fastlane blog.)
There are a couple of points to make about this. First, "crashes" and "fatalities" are used almost interchangeably, but these are very different things. Fatalities are part of a very small percentage of crashes. Fatalities inside of cars increase with the speed the car is traveling, so there are a number of potential confounding effects here. One is that people drive differently on local streets than on the freeway. There are far more things to pay attention to on local streets than on freeways, too, where traffic tends to move in the same direction at about the same speed.
The second thing is that pedestrian injuries and fatalities are often not included in the vehicle crash statistics, though New York City recently released a study on this very issue. Distracted drivers running into pedestrians and cyclists us a major problem in most cities, and in New York driver inattention was cited in nearly 36% of crashes resulting in pedestrians killed or seriously injured. Overall pedestrians accounted for 52% of traffic fatalities from 2005-2009. But the good news is that traffic fatalities declined by 35% between 2001 and 2009. During that period cell phones were banned for drivers, among other measures.
In any event, I think where you see the greatest benefit from texting and cell bans is on city streets, not major highways. I suspect that if you look at local statistics you will find that these bans have saved many lives and prevented lots of broken bones.