Statistical Analysis of Safety Performance of Displaced Left-Turn Intersections: Case Studies in San Marcos, Texas

Displaced left-turn (DLT) intersections are designed to increase the mobility of vehicles by relocating the left-turn lane (lanes) to the far-left side of the road upstream of the main signalized intersection. Since DLT is a relatively new design and very limited crash data are available, previous studies have focused mainly on the analysis of its operational performance rather than its safety performance. To fill this gap, in this study, we investigated the safety performance of two DLT intersections located in San Marcos, Texas. Crash data from 2011 to April 2018 were extracted from the TxDOT Crash Record Information System (CRIS). These crash data were analyzed using two different approaches, i.e., statistical analysis and collision diagram-based analysis. The results of this study indicated that DLT did not increase the overall crash frequencies at the studied intersections. Traffic crashes related to left turns and right turns were reduced significantly by DLT. Meanwhile, it also caused safety issues related to traffic signage, traffic signal, geometric design, and access management at DLT intersections. Thus, in the implementation of DLT intersections, traffic engineers need to carefully consider different aspects of the DLT intersection design, including access management, traffic signal coordination, and driver acceptance. As a result of these analyses, recommendations were provided for the safe implementation of the DLT design in the future.

[1]  J P Pitaksringkarn Measures of Effectiveness for Continuous Flow Intersection: A Maryland Intersection Case Study , 2005 .

[2]  Mohamed Abdel-Aty,et al.  Evaluation of displaced left-turn intersections , 2020 .

[3]  Michael G Bruce,et al.  Continuous Flow Intersections , 2006 .

[4]  C. Berkowitz,et al.  Continuous flow intersection: A public private partnership , 1996, Vehicle Navigation and Information Systems Conference, 1996.

[5]  Praveen Edara,et al.  Performance Analysis of Parallel Flow Intersection and Displaced Left-Turn Intersection Designs , 2010 .

[6]  Assimakopoulos,et al.  INTERURBAN ACCIDENT PREDICTION BY ADMINISTRATIVE AREA APPLICATION IN GREECE , 1994 .

[7]  Joe G Bared,et al.  Design and Operational Performance of Crossover Displaced Left-Turn Intersections , 2004 .

[8]  Joseph E. Hummer,et al.  Travel Time Comparisons Between Seven Unconventional Arterial Intersection Designs , 2001 .

[9]  Joseph E. Hummer,et al.  Alternative Intersections/Interchanges: Informational Report (AIIR) , 2010 .

[10]  David A Noyce,et al.  Development of a Safety Performance Function for Signalized Diamond Interchange Ramp Terminals , 2010 .

[11]  Hesham Rakha,et al.  Continuous flow intersections: A safety and environmental perspective , 2010, 13th International IEEE Conference on Intelligent Transportation Systems.

[12]  Milan Zlatkovic,et al.  Performance Matrices for Evaluating Innovative Intersections and Interchanges , 2015 .

[13]  Gang-Len Chang,et al.  Unconventional Arterial Intersection Designs Initiatives , 2007 .

[14]  Gang-Len Chang,et al.  Comparison of Three Unconventional Arterial Intersection Designs : Continuous Flow Intersection , Parallel Flow Intersection , and Upstream Signalized Crossover , 2022 .

[15]  Mohamed El Esawey,et al.  Comparison of Two Unconventional Intersection Schemes , 2007 .

[16]  Michael D Fontaine Operational Comparison of a Continuous Flow Intersection to Conventional Alternatives , 2009 .