Safety Analysis and Crash Modification Factors of an Adaptive Signal Control Technology along a Corridor

The main objective of this study is to determine the safety effectiveness of the adaptive signal control technology (ASCT) SynchroGreen using an observational before and after study applying the Empirical Bayes (EB) method. Both national (Highway Safety Manual (HSM)) and state specific (Illinois) safety performance functions (SPF) were selected and calibrated for the local conditions. A total of 14 SPFs from the HSM and 3 additional from Illinois were calibrated and crash modification factors (CMF) were developed. For multiple-vehicle fatal and injury (FI) crashes at all intersections (four-legged and three-legged combined), the CMF was 0.67, which was not statistically significant at 95 percent confidence level (it was significant at 87 percent). For four-legged-only intersections the CMF was 0.67 as well, which was not significant with 95 percent confidence (it was significant at 85 percent). The 87 and 85 percent are not confidence levels used in practice, however they clearly indicate a decreasing trend in FI crashes due to the implementation of ASCT. For property damage only (PDO) and total crashes, all CMF computed were very close to one indicating no crash reduction due to the implementation of ASCT. The CMF for Illinois KAB crashes (fatal, type A injury, and type B injury crashes combined) was found to be 0.68, which was not significant at 95 percent confidence level (it was significant at 71 percent indicating a decreasing trend in these types of crashes). Paired t-test results showed no reduction in sideswipe same direction, turning, and type B injury crashes. However, angle, rear end, type A and type C injury crashes showed slight decreases that were not significant.

• Record URL:
  https://apps.ict.illinois.edu/projects/getfile.asp?id=8754
• 
• Record URL:
  https://rosap.ntl.bts.gov/view/dot/41710
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/01979191
• Corporate Authors:

  University of Illinois, Urbana-Champaign

  Illinois Center for Transportation
  Department of Civil and Environmental Engineering
  Urbana, IL  United States  61801

  Illinois Department of Transportation

  Bureau of Research
  Springfield, IL  United States 

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Osorio, Jesus J
  • Benekohal, Rahim (Ray) F
• Publication Date: 2019-1

Language

• English

Media Info

• Media Type: Digital/other
• Features: Appendices; Figures; Maps; Photos; References; Tables;
• Pagination: 75p
• Serial:
  • Civil Engineering Studies, Illinois Center for Transportation Series
  • Issue Number: 19-001
  • Publisher: University of Illinois, Urbana-Champaign
  • ISSN: 0197-9191

Subject/Index Terms

• TRT Terms: Adaptive control; Bayes' theorem; Before and after studies; Calibration; Crash modification factors; Crash rates; Crash severity; Signalized intersections; Traffic signal control systems
• Identifier Terms: Highway Safety Manual; Safety Performance Functions
• Geographic Terms: Illinois
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 01698791
• Record Type: Publication
• Report/Paper Numbers: FHWA-ICT-19-001, UILU-ENG-2019-2001, ICT-19-001
• Contract Numbers: R27-127
• Files: NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: Mar 13 2019 3:55PM