Keeping Drivers Right: Iowa’s Low-Cost Strategy to Prevent Wrong-Way Entries

Abstract

Wrong-way driving (WWD) crashes, though infrequent, carry a high risk of fatal and severe outcomes. The Iowa Department of Transportation (Iowa DOT) identified recurring WWD movements at partial cloverleaf (Parclo B) interchanges and implemented a series of low-cost, human-factor-based signing and marking countermeasures. The “gateway treatment” approach emphasized driver guidance through enhanced “Do Not Enter” and “Keep Right” signing and improved pavement markings. Evaluation across multiple sites showed an 88 percent reduction in WWD events per month and no crashes at treated locations since implementation. The results demonstrate that simple, data-driven strategies can deliver substantial safety benefits and serve as a practical model for other agencies addressing WWD risks.