Analysis and methods of improvement of safety at high-speed rural intersections [technical summary].

Details

• Creators:
  Tarko, Andrew P.
• Corporate Creators:
  Purdue University
• Corporate Contributors:
  Purdue University. Joint Transportation Research Program ; Indiana Department of Transportation
• Subject/TRT Terms:
  • Rural areas
  • Rural highways
  • Rural transportation
  • Intersections
  • Traffic models
  • Traffic speed
  • Traffic safety
  • Countermeasures
  • Safety
  • Multivariate analysis
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• Resource Type:
  Tech Report
• Geographical Coverage:
  Indiana
• Edition:
  Technical summary.
• Corporate Publisher:
  Purdue University. Joint Transportation Research Program
• Abstract:
  INTRODUCTION: Since 2006, INDOT has been preparing an annual fivepercent ; report that identifies intersections and segments ; on Indiana state roads that require attention due to the ; excessive number and severity of crashes. Many of the ; identified intersections are two-way, stop-controlled intersections ; located on high-speed, multi-lane, rural roads. ; Some contributing design and human factors have been ; identified, while other factors still await investigation. ; Multivariate ordered probit models have been developed ; to help identify additional factors of the frequency and severity ; of crashes. These models can estimate how much ; different factors increase the frequency of crashes at ; several levels of injury severity (fatal/incapacitating, nonincapacitating/ ; possible, and property-damage-only). They ; have a unique ability to account for unobserved but common ; conditions that affect all of the crash severity levels. ; Recommendations for safety countermeasures are made ; based on both of these research results and our study of ; published reports of other authors. ; FINDINGS: The statistical analysis was performed on 553 existing ; intersections in Indiana and 72 existing intersections in ; Michigan using crash data reported during a four-year ; period. The identified safety factors include the following: ; presence of horizontal curves within the intersection vicinity, ; traffic volume on the major road, land use, population ; of the area surrounding the intersection, the minor road ; functional class (traffic volume on minor road unknown), ; nearby at-grade railroad crossings, intersection conspicuity ; to drivers on the major road, acceleration lanes for ; both left and right turns, median width, intersection angle, ; and number of intersection legs. These results are in line ; with other research results as documented in the literature ; review. ; Based on the results of this and other studies, recommendations ; are made to improve safety at new intersections ; as well as at existing intersections. For new intersections, ; construction of medians wider than 80 feet is suggested. ; Where this is not possible and a narrower median needs ; to be constructed, adding a parallel acceleration lane for ; vehicles turning left from the minor road is suggested. Intersections ; should be placed at a sufficient distance from ; horizontal curves and from at-grade railroad crossings. ; Solutions with indirect left-turn lanes (Michigan U-turns, ; J-turns) are recommended. ; At existing intersections experiencing excessive numbers ; of crashes involving vehicles from the minor road, median ; closure should be considered or a median opening should ; be restricted to certain maneuvers. Median acceleration ; lanes can be added in order to allow a two-stage maneuver ; for left turns from the minor road. Enhanced guide ; and warning signage can be used to improve intersection ; conspicuity; adding road illumination can especially help ; at night. The practice of adding left- and right-turn bays ; should be continued as this is a proven intersection safety ; improvement practice. Applying these countermeasures ; may help improve safety and avoid the construction of ; expensive grade separations. ; Finally, advanced intersection collision avoidance systems, ; such as road-side dynamic signs warning drivers ; on the minor road about a short gap on the major road, ; should be the subject of pilot studies in Indiana. Experiments ; in other states have indicated that these systems ; help drivers choose safe gaps.
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• Format:
  PDF
• Funding:
  SPR-3316
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/24457/dot_24457_DS1.pdf
• File Type:
  [PDF - 600.09 KB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:1996af1fe3aceabbc5880260cb14a795d2696c3184ef3427f5d7a0534ccbc366cd98ca69a13d26d0bcf9163d4fbe605cf4ab423f836a36b10677090fe3ed9286