Pavement markings provide a wide variety of information to drivers. For pavement
markings to be seen by drivers at night, they must be retroreflective. Like many other
roadway materials, pavement markings deteriorate over time and lose their ability to
retroreflect headlamp illumination. There is general consensus among practitioners that this
reduced performance may be a causative agent in the rate and severity of nighttime crashes,
although previous research has not yet quantified the relationship. This work examines the
relationship between safety and pavement marking retroreflectivity using data from selected
highways in North Carolina and attempts to quantify the strength of the relationship
between pavement marking retroreflectivity and safety. Safety is defined as the propensity of
a segment to experience a crash during a given period of time. The framework of Causal
Bayesian Networks is used to model the probabilistic dependence between pavement
marking retroreflectivity and safety. Results indicate that the probability of a target crash
increases by almost 87 percent with a decrease in retroreflectivity levels from above 350
mcd/m2/lux to below 207.6 mcd/m2/lux, for two- and four-lane roads.
