Effects of Traffic Conditions on Safety of Urban Networks

The objective of this work is to understand if a relationship between traffic congestion and safety on urban roadways exist. To do so, crash data over the network of Zurich, Switzerland, is linked to speed and traffic flow data from the same network. By aggregating the data, the crash risk in relation to traffic states is analyzed: (i) over the entire network for different times of day; and (ii) for different links on the network for a given time period. In addition, the influence of speed on the severity of the crashes is also investigated. It is found that at the network level the crash risk (number of crashes per car) is higher during times when the average network speed is lower (5-7 pm). Lower speeds are observed during this time period typically due to congestion. Hence, at the network level, there is evidence for congestion being an indicator of increased crash risk. During the same (congested) time period, it is also observed that crashes mostly happened on links with medium speeds, which could be due to speed variations on individual links being higher during the congested time periods. It is also found that, as expected, more severe crashes happen at higher speeds throughout the day

• Supplemental Notes:
  • This paper was sponsored by TRB committee ANB10 Transportation Safety Management.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Stempfel, Julie
  • Guler, S Ilgin
  • Menendez, Monica
  • Brucks, Wernher
• Conference:
  • Transportation Research Board 93rd Annual Meeting
  • Location: Washington DC
  • Date: 2014-1-12 to 2014-1-16
• Date: 2014

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 17p
• Monograph Title: TRB 93rd Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Crash data; Crash risk forecasting; Crash severity; Highway safety; Traffic congestion; Traffic data; Traffic speed; Urban highways
• Geographic Terms: Zurich (Switzerland)
• Subject Areas: Data and Information Technology; Highways; Safety and Human Factors; I83: Accidents and the Human Factor;

Filing Info

• Accession Number: 01519546
• Record Type: Publication
• Report/Paper Numbers: 14-2016
• Files: TRIS, TRB, ATRI
• Created Date: Mar 26 2014 10:07AM