A study performed by the Texas A&M Transportation Institute for the Texas Department of Transportation examined signing strategies for warning motorists of flooding on roadways, with the goal of creating uniform signing guidelines for flooding or water-crossing situations. Two human factors studies were conducted to provide information about driver responses to signing treatments that warn of flooded roadways. The first was a series of focus groups that explored driver decision processes and information preferences related to flooded roadways. The focus group results indicated that drivers tended to base decisions about proceeding on a flooded road on their perceptions of the depth and speed of the water (which were not always reliable), as well as other visual cues; drivers preferred positive guidance in the form of directive messages and active signs. The second study was a survey that presented drivers with pictures of roadways using various signing treatments, followed by questions about how they would respond to each situation pictured. The survey results supported the focus group findings about drivers greater trust of active signs versus passive signs and further emphasized the effects of visual cues on drivers decisions about proceeding on flooded roads.