Incorporating Traffic Control and Safety Hardware Performance Functions into Risk-based Highway Safety Analysis

  • Zongzhi Li
  • Hoang Dao Illinois Institute of Technology
  • Harshingar Patel Illinois Institute of Technology
  • Yi Liu Wuhan University of Technology
  • Bei Zhou Chang'an University
Keywords: traffic control, safety hardware, safety performance function, highway safety, risk analysis,


Traffic control and safety hardware such as traffic signs, lighting, signals, pavement markings, guardrails, barriers, and crash cushions form an important and inseparable part of highway infrastructure affecting safety performance. Significant progress has been made in recent decades to develop safety performance functions and crash modification factors for site-specific crash predictions. However, the existing models and methods lack rigorous treatments of safety impacts of time-deteriorating conditions of traffic control and safety hardware. This study introduces a refined method for computing the Safety Index (SI) as a means of crash predictions for a highway segment that incorporates traffic control and safety hardware performance functions into the analysis. The proposed method is applied in a computation experiment using five-year data on nearly two hundred rural and urban highway segments. The root-mean square error (RMSE), Chi-square, Spearman’s rank correlation, and Mann-Whitney U tests are employed for validation.

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Zongzhi Li
Director of IIT Center for Work Zone Safety and Mobility(Renamed as IIT Sustainable Transportation and Infrastructure Research- STAIR Center)Director of IIT Transportation Engineering LaboratoryDepartment of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology3201 South Dearborn Street, Chicago, Illinois 60616
Hoang Dao, Illinois Institute of Technology

Ph.D. candidate

Transportation Engineering

Harshingar Patel, Illinois Institute of Technology


Transportation Engineering Program

Yi Liu, Wuhan University of Technology


College of Waterway Navitation

Bei Zhou, Chang'an University


College of Highways


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How to Cite
Li Z, Dao H, Patel H, Liu Y, Zhou B. Incorporating Traffic Control and Safety Hardware Performance Functions into Risk-based Highway Safety Analysis. Promet [Internet]. 2017Apr.19 [cited 2024Jun.21];29(2):143-5. Available from: