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Wrong-way driving on highways is a serious and persistent safety problem that results in more than 300 deaths each year nationwide. While the total number of highway traffic fatalities in the United States has been declining since 2004, the number of wrong-way driving fatalities has held steady. This troubling trend has led to an increased interest in safety countermeasures to reduce wrong-way driving and sparked new research on the subject.

Working with Roadway Safety Institute researcher Albert Luo at Southern Illinois University Edwardsville, Hugo Zhou, an associate professor in the civil engineering department at Auburn University, has been at the forefront of that effort as one of the country’s leading experts on wrong-way driving. As part of the Roadway Safety Institute seminar series, Zhou presented findings from a project that collected six years of crash data from the Illinois Department of Transportation to identify and analyze wrong-way crashes.

“When we began our first wrong-way driving study, there was no national effort to reduce wrong-way driving crashes and the data was challenging to work with,” says Zhou. “In addition, it is difficult to identify wrong-way driving entry points: only one percent of wrong-way driving incidents end up in a crash because most drivers self-correct quickly. Those that do end in a crash are often fatal, so it is difficult to determine where the driver entered.”

Two of Zhou’s recently published reports (for the Illinois Center for Transportation and the American Traffic Safety Services Association) and the creation of a National Wrong-Way Driving Summit have helped address those previous gaps. The result is a wealth of new wrong-way driving data, along with more comprehensive resources for highway departments interested in implementing safety countermeasures to prevent wrong-way driving.

To identify specific locations where wrong-way crashes occur, Zhou and his research team developed a new method of ranking high-crash locations by assigning higher weights to the known entry points for wrong-way driving crashes and lesser weights to possible entry points for wrong-way driving crashes in which the entry point was unknown. They applied the new method to Illinois data and ranked the top 10 entry locations for wrong-way driving crashes in the state, then conducted field reviews and identified safety countermeasures for those locations.

Zhou’s research findings have shed additional light on the contributing factors leading to wrong-way driving crashes. An analysis of where wrong-way drivers enter the highway revealed that interchange type is a significant contributing factor, with many wrong-way drivers entering from interchanges where the on and off ramps are close together, such as compressed diamond interchanges.

“We found also a high percentage of wrong-way crashes occur after midnight and in the early morning because of the greater number of impaired drivers at this time and low traffic volumes that make it easier to enter the road going the wrong way,” says Zhou. “Wrong-way drivers are most often senior drivers, male drivers, and [drivers] impaired by drugs, alcohol, or fatigue.”

The new wrong-way driving publications present a variety of countermeasures that can be used to help prevent wrong-way driving crashes and fatalities. Low-cost countermeasures that have been effectively deployed in the United States are presented as case studies; these measures include low-mounted wrong-way signage, high-visibility signage, raised pavement markings, access management for exit ramps, channelizing devices, ITS detection and warning systems, and countermeasure packages for partial-cloverleaf interchanges.

In addition to these low-cost countermeasures, Zhou’s team also looked at geometric design improvements. “We discovered that using geometric design features such as median barriers, control radiuses, and channelizing islands can reduce the risk of wrong-way crashes by making it extremely difficult for drivers to enter the highway going the wrong direction.”

Zhou and Luo are currently working on research funded by the Roadway Safety Institute on the potential of directional rumble strips to reduce wrong-way driving at freeway entries.

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