Even though wrong way driving (WWD) crashes on controlled-access highways are infrequent (less than 1 percent of all traffic crashes in Texas), they result in severe injuries and fatalities, and continue to occur despite more than 50 years of research and countermeasure implementation. Questions remained about which countermeasures actually catch the attention of wrong way drivers and are effective at getting them to self-correct before reaching the main lanes, especially those drivers that are driving under the influence of alcohol. In addition, recent implementations of WWD countermeasures and mitigation methods in several locations in Texas provided the opportunity to assess the effectiveness of these tools in actual operational environments. The Texas Department of Transportation (TxDOT) also posts wrong way driver warning messages on dynamic message signs (DMSs); however, no guidance existed about the design of these types of messages.