Restricting intersection visibility to reduce approach speeds.

This paper reports the field test of a visual restriction treatment for a rural intersection with a high rate of injury crashes. A human factors analysis of the asymmetric pattern of crashes at the site suggested that most of the crashes were the result of anticipatory decision-making occasioned by visual characteristics of the eastbound approach to the intersection. The field test examined the effectiveness of a visual restriction treatment directed at eliminating drivers' anticipatory decision-making. The treatment consisted of a hessian screen erected along the eastbound approach to the intersection beginning 125 m prior to intersection and ending 25 m prior to intersection. Over 2 days of testing, approximately 300 drivers' reactions at the intersection were observed and their responses to a brief survey recorded. The test indicated a 23% reduction in the 80th percentile and mean approach speeds and elimination of all approach speeds over 57 km/h following introduction of the treatment. Survey results showed that the treatment was visually acceptable to the majority of drivers using the intersection and did not affect its perceived safety. Follow-on analyses compared speed data before the treatment, and 2, 21, and 37 weeks after installation of the treatment. These analyses showed that approach speeds remained low; 30% lower than pre-treatment speeds for both the 80th percentile and the average approach speeds. Of perhaps the greatest significance, no crash resulting in serious injury or death has occurred at the intersection since installation of the treatment to the present time. (Author/publisher).