Study Details
Study Title: When driving on the left side is safe: Safety of the diverging diamond interchange ramp terminals
Authors: Claros et al.
Publication Date:MAR, 2017
Abstract: How safe are the ramp terminals of a diverging diamond interchange (DDI)? This paper answered this question using data from DDI sites in Missouri. First, crash prediction models for ramp terminals for different crash severities were developed. These models were then utilized in the Empirical Bayes (EB) evaluation of DDI ramp terminals. Due to inconsistencies in crash reporting for freeways in Missouri, individual crash reports were reviewed to properly identify ramp terminal crashes. A total of 13,000 crash reports were reviewed for model development and EB evaluation. The study found that the DDI ramp terminals were safer than the conventional diamond signalized terminals. The DDI ramp terminals experienced 55% fewer fatal and injury crashes, 31.4% fewer property damage only crashes, and 37.5% fewer total crashes.
Study Citation: Claros, B., P. Edara, and C. Sun. "When driving on the left side is safe: Safety of the diverging diamond interchange ramp terminals." Accident Analysis and Prevention, Vol. 100, (2017) pp. 133-142.
Related Citations: Related Citation 1: Edara, P., C. Sun, B. Claros, and H. Brown. "Safety Evaluation of Diverging Diamond Interchanges in Missouri." Report No. cmr 15-006. Missouri Department of Transportation. Jefferson City, Missouri. (January 2015). Related Citation 2: Claros, B., P. Edara, C. Sun. "Site-specific Safety Analysis of Diverging Diamond Interchange Ramp Terminals". Transportation Research Record No. 2556, Transportation Research Board of the National Academies of Science, Washington, D.C., (2016).
CMFs Associated With This Study
Category: Interchange design
Countermeasure: Convert diamond interchange to Diverging Diamond Interchange (DDI) or Double Crossover Diamond (DCD)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 0.45 | 55 |  | All | K,A,B,C | All | Urban |
| 0.686 | 31.4 | | All | O | All | Urban |
| 0.625 | 37.5 | | All | All | All | Urban |
