title: Safety impacts of red light cameras at signalized intersections based on cellular automata models.
abstract: OBJECTIVE
  This study applies a simulation technique to evaluate the hypothesis that red light cameras (RLCs) exert important effects on accident risks. Conflict occurrences are generated by simulation and compared at intersections with and without RLCs to assess the impact of RLCs on several conflict types under various traffic conditions.
  
  
  METHODS
  Conflict occurrences are generated through simulating vehicular interactions based on an improved cellular automata (CA) model. The CA model is calibrated and validated against field observations at approaches with and without RLCs. Simulation experiments are conducted for RLC and non-RLC intersections with different geometric layouts and traffic demands to generate conflict occurrences that are analyzed to evaluate the hypothesis that RLCs exert important effects on road safety.
  
  
  RESULTS
  The comparison of simulated conflict occurrences show favorable safety impacts of RLCs on crossing conflicts and unfavorable impacts for rear-end conflicts during red/amber phases. Corroborative results are found from broad analysis of accident occurrence.
  
  
  CONCLUSIONS
  RLCs are found to have a mixed effect on accident risk at signalized intersections: crossing collisions are reduced, whereas rear-end collisions may increase. The specially developed CA model is found to be a feasible safety assessment tool.
authors.affiliation: a Centre for Infrastructure Systems, School of Civil and Environmental Engineering , Nanyang Technological University , Singapore.
authors.forename: C
authors.initials: C
authors.lastname: Chai
authors.forename: Y D
authors.initials: YD
authors.lastname: Wong
authors.forename: K M
authors.initials: KM
authors.lastname: Lum
mesh_terms: D000063:Accidents, Traffic / Q000517:prevention & control*; D001334:Automobile Driving / Q000331:legislation & jurisprudence*; D002138:Calibration; D003198:Computer Simulation; D004779:Environment Design; D005240:Feasibility Studies; D006801:Humans; D035846:Law Enforcement / Q000379:methods*; D008962:Models, Theoretical; D010781:Photography; D015203:Reproducibility of Results; D018570:Risk Assessment; D012449:Safety
keywords: cellular automata; red light cameras; signalized intersection; vehicle conflicts