Safer Streets: The Measured Effectiveness of Hartford’s Citywide Traffic Calming Program

The City of Hartford, Connecticut made an innovative move in 2005 when it developed a comprehensive citywide traffic calming master plan. This plan, the first of its kind in the United States and the process used to develop it, was presented at the 2005 Institute of Transportation Engineers (ITE) Technical Conference and Exhibit. Two years later, as this ambitious plan is gradually implemented, the city is collecting “before” and “after” data for many of the traffic calming devices so that their impact on vehicular safety can be measured and so that future deployments may be validated. This paper presents a case study on the effects of deploying road diets on crash frequency. Roads that were placed on road diets were compared to similar roads that did not receive any treatments. The Empirical Bayesian (EB) method was used to predict the “expected” crash rate during the “after” period without implementation based on the control sites. The observed “before” crash rates, the crash rate expected without improvement, and the observed “after” crash rate were compared and discussed in this paper.