Driving under the (Cellular) Influence (counterintuitive results)

We investigate the causal link between driver cell phone use and crash rates by exploiting a natural experiment induced by the 9 pm price discontinuity that characterizes a majority of recent cellular plans. We first document a 7.2 percent jump in driver call likelihood at the 9 pm threshold. Using a prior period as a comparison, we next document no corresponding change in the relative crash rate. Our estimates imply an upper bound in the crash risk odds ratio of 3.0, which rejects the 4.3 asserted by Redelmeier and Tibshirani (1997). Additional panel analyses of cell phone ownership and cellular bans confirm our result.

That is from a recently published paper by  Saurabh & Pathania (American Economic Journal: Economic Policy, August 2013). A draft is here.

To illuminate or not to illuminate

Overall, the presence of roadway intersection lighting was found to be associated with an approximately 12% lower night-to-day crash ratio than unlighted intersections. In the parallel analytical approach, visual performance analyses based on roadway intersection lighting practices in Minnesota were made for the same intersection types investigated in the statistical approach. The results of both approaches were convergent, suggesting that visual performance improvements from roadway lighting could serve as input for predicting improvements in crash frequency.

Source.  

Do Traffic Tickets Reduce Motor Vehicle Accidents?

This [2012] paper exploits the dramatic increase in tickets during the Click-it-or-Ticket campaign to identify the causal impact of tickets on accidents using data from Massachusetts. I find that tickets significantly reduce accidents and non-fatal injuries. However, there is limited evidence that tickets lead to fewer fatalities. I provide suggestive evidence that tickets have a larger impact at night and on female drivers. 

That is from the abstract of Dara N. Lee's paper. 

Fascinating, especially because of the implications for most developing countries where speed limits are generally not enforced.