Expectancy and Positive guidance are two fundamental human factors concepts that are employed when designing roadways in the United States to ensure that drivers have sufficient visual information to safely navigate. In roadway design cases, human factors experts analyze the impact of the design and condition of the roadway environment on a driver’s performance by evaluating whether there was sufficient positive guidance available to the driver and whether the roadway conditions were consistent with driver expectancies. 

For example, a human factors expert may investigate whether there was sufficient information available to the driver on the roadway to avoid the collision, whether that information was available in sufficient time to avoid the collision, and/or whether additional signage or traffic control devices would have prevented the collision.