Traffic Parameter Methods for Surrogate Safety: A Comparative Study of Three Mobile Sensor Technologies

Although maintaining adequate levels of safety is a universal requirement for modern road networks, the preferred techniques for defining and quantifying safety remain debated. Traditional studies have frequently relied on crash data as a method for assessing safety, though crash-based methods are reactive, requiring crashes to occur before causes can be identified and countermeasures can be implemented. In response, surrogate safety measures, non-crash measures that are physically and predictably related to motor vehicle crashes, have become popular. Existing work has predominantly focused on traffic parameter data collected by loop detectors, without comparison of surrogate measures reported by different detection technologies. The purpose of this paper is to evaluate how three mobile traffic sensors, microwave radar, plate magnetometer, and video-based devices, report safety surrogate measures. The surrogates considered included conflicts (measured by time-to-collision, TTC), temporal speed variation (measured by the coefficient of variation of speed, CVS), and lateral speed variation (measured by the average difference in speed, ΔS). For rear-end TTC, the video-based sensor reported relatively more conflicts than the radar and magnetometer, which performed similarly. CVS calculated from radar data was consistently higher than for the video. These measures are largely influenced by the overestimation bias in speed measurement present in video-based data. Utilizing the average difference in speed across lanes to quantify lateral speed variation is independent of mean speed, the overestimation bias of the video is inconsequential, and the results from the radar and video detectors are similar as expected.

• 
• Supplemental Notes:
  • This paper was sponsored by TRB committee ANB20 Safety Data, Analysis and Evaluation.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Stipancic, Joshua
  • Miranda-Moreno, Luis
• Conference:
  • Transportation Research Board 94th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2015-1-11 to 2015-1-15
• Date: 2015

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 15p
• Monograph Title: TRB 94th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Magnetometer detectors; Radar detectors; Traffic data; Video imaging detectors
• Uncontrolled Terms: Conflict analysis; Surrogate safety measures; Time to collision
• Geographic Terms: Montreal (Canada)
• Subject Areas: Data and Information Technology; Highways; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01555308
• Record Type: Publication
• Report/Paper Numbers: 15-1340
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Feb 26 2015 10:05AM