Improving intersection safety through design and operations.

Red Light Running, is an issue that is receiving considerable attention from traffic engineers and the public at large. It is one of the many behaviors that comprise the group of behaviors generally categorized as Aggressive Driving. Red Light Running has become a hot topic, because of the consequences associated with the behavior. Estimates put the annual number of crashes attributed to Red Light Running at 89,000. These crashes produced 80,000 injuries and 1,000 fatalities. Concern over this behavior and its consequences has peaked interest in automated enforcement. It has also prompted the traffic engineering community look at the engineering of traffic signal installations to determine if improvements can be made to reduce the chance of a motorist running a red traffic signal. Evidence that engineering changes can make a difference were reported by Polanis (2). He reported the results of 38 before and after studies where 8" signal heads were replaced with 12" signal heads. The paper reported an aggregate reduction in right angle crashes, of 49%, on the approaches where the signal heads were upgraded. In addition, the paper reported declines in right angle crashes at 36 of the 38 intersections. Nineteen (19) of these declines were statistically significant. Since 1986, Winston-Salem's Safety Improvement Program has been identifying locations where crashes form patterns. Following the identification of these locations, low cost traffic engineering tools and techniques, that can be employed quickly, have been used to treat crash patterns evident at these locations. Each time an intervention was deployed, an evaluation was conducted. The results of these evaluations have been catalogued in a safety library. This library currently has data on 364 completed before and after studies that include over 14,500 crashes. Many of the studies tracked the effects of engineering interventions at signalized intersections. Eight interventions, targeting right angle crashes at signalized intersections, have at least five completed before and after studies. Data on each of these interventions is presented as evidence that engineering solutions to Red Light Running exist. All the crash data presented in this report are derived from collision diagrams prepared directly from police crash reports. The paper presents 8 interventions and lists the crash statistics associated with each intervention. In each of these interventions, right angle crashes are targeted crashes.