SAFETY EFFECTS OF PAVEMENT MARKING RETROREFLECTIVITY:AN APPLICATION OF CAUSAL BAYESIAN NETWORKS

Open Access
Author:
Karwa, Vishesh
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 24, 2009
Committee Members:
  • Eric Todd Donnell, Thesis Advisor
Keywords:
  • safety
  • Pavement marking retroreflecitivyt
  • Causal Inference
  • Bayeisan Networks
Abstract:
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.