Evaluation of j-turn intersection design performance in Missouri, final report.

Details

• Creators:
  Edara, Praveen ; Sun, Carlos ; Breslow, Sawyer
• Corporate Creators:
  University of Missouri--Columbia. Dept. of Civil Engineering
• Corporate Contributors:
  United States. Department of Transportation. Research and Innovative Technology Administration
• Subject/TRT Terms:
  At Grade Intersections Before And After Studies Crash Analysis Crash Rates Crash Severity Field Studies Highway Design Rural Highways Surveys Traffic Crashes Turning Traffic

  More +
• Publication/ Report Number:
  MATC-MU: 179;25-1121-0003-179
• Resource Type:
  Tech Report
• Geographical Coverage:
  Missouri
• Corporate Publisher:
  Mid-America Transportation Center
• Abstract:
  Research shows that a high percentage of crashes that take place on high-speed rural expressways occur at intersections
  
  with minor roads. One low-cost alternative design for improving the safety of at-grade intersections on such expressways is
  
  the J-turn. In the last few years, the Missouri Department of Transportation has converted some two-way stop controlled
  
  (TWSC) intersections into J-turns. This study evaluated the effectiveness of the J-turn intersection design in Missouri
  
  utilizing field studies, a public survey, crash analysis, and traffic conflict analysis. The field studies collected detailed video
  
  data at a J-turn site and a control site. The crash analysis included a statistically rigorous empirical Bayes before-after
  
  safety evaluation of five J-turn sites in Missouri. The J-turn design resulted in a 34.8% reduction in crash frequency for all
  
  crashes and a 53.7% reduction in crash frequency for all injury and fatal crashes. Both reductions were significant at the
  
  95% confidence level. Annual disabling injury crashes and minor injury crashes decreased by 86% and 50%, respectively.
  
  None of the five sites exhibited a fatal crash following J-turn implementation. This five-site analysis showed that annual
  
  right angle crashes decreased from 6.3 to 1.3, a 80% reduction. One of the most severe crash types, the left turn, right angle
  
  crash, was completely eliminated by the J-turn. One conflict measure, average time to collision, was found to be four times
  
  higher at the J-turn site compared to the control TWSC site among minor road turning vehicles, indicating greater safety at
  
  the J-turn site. The average wait time at the J-turn site was half the wait time at the control site, while the average travel
  
  time at the J-turn site was approximately one minute greater than at the TWSC site. When the public was surveyed
  
  regarding trip time perceptions resulting from the J-turn, the majority said there was no adverse effect. A high percentage
  
  of minor road left turning and through movements at the J-turn site merged into the travel lanes within the first 400 feet of
  
  the acceleration lane. Public opinion regarding the J-turn at US 63 and Deer Park Rd was mixed. Frequent concerns raised
  
  by respondents included difficulty merging following the U-turn, improper use of acceleration and deceleration lanes,
  
  insufficient U-turn radius to accommodate large vehicles, and driver confusion.
  
  
• Format:
  PDF
• Funding:
  MATC TRB RiP No. 1250775
• Collection(s):
  University Transportation Centers US Transportation Collection
• Main Document Checksum:
  urn:sha-512:27248615c110824bcbab91d6eac3d74203a9c3cb113fa98fa88b25dbe441cf6379e98942f5435586d99100f5bdf6a4d9271db81458bb864580ab7549b9e6dd5d
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/26914/dot_26914_DS1.pdf
• File Type:
  [PDF - 2.18 MB ]