Analysis of roadway departure crashes on two-lane rural roads in Texas.

This three-year research effort was undertaken to identify factors that influence the number and severity of roadway departure crashes on rural two-lane highways in Texas and provide engineering countermeasures to reduce this type of crash. The study objectives were accomplished by analyzing crash, traffic flow, and geometric data between 2003 and 2008 and conducting site visits at 20 sites having the highest crash rates at four Texas Department of Transportation (TxDOT) districts. The study results showed that the proportion of roadway departures varied from 25 percent to 52 percent for all crashes occurring on the rural two-lane highway network. Proportionally more crashes occur on horizontal curves than on tangents and during nighttime. Distracted driving and speeding were found to be important contributing factors. To help reduce the number and severity of roadway departures, the research team proposed several medium- to low-cost countermeasures that can realistically be implemented by TxDOT. These countermeasures were grouped into three categories: targeted for horizontal curves, general applications, and new and innovative treatments. For each treatment, the information focused on the general characteristics, key design features, safety effectiveness, cost (when available), and additional resources where the reader can find more detailed information about the treatment. More than 25 treatments were described for reducing roadway departure crashes.