01663063

Component

The installation of Diverging Diamond Interchanges (DDIs) has grown exponentially in the United States. There are limited real-world assessments of the safety benefits because the implementation of DDIs in the United States is relatively new. This study provides a project level safety effectiveness evaluation of two DDIs in Minnesota using two observational before-after evaluations. Before the implementation of the DDIs, both sites were classified as signalized intersections. The Naïve and Empirical Bayes (EB) before-after approaches were used to determine the safety savings of converting the signalized intersections into DDIs. Crash Modification Factors (CMF) were used to measure the safety effectiveness of the DDIs. Crash data and annual volume data from both sites before and after the DDI implementation was used in the analysis. The results indicate that the average CMF is 0.48 for the Naïve method and 0.42 for the EB method. The findings prove that the DDI design is a valid and reliable safety countermeasure.

This paper was sponsored by TRB committee ANB25 Standing Committee on Highway Safety Performance.

18-06071

English

17p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Before and after studies; Crash data; Crash modification factors; Diamond interchanges; Highway design; Highway safety; Traffic volume

Minnesota

Design; Highways; Operations and Traffic Management; Safety and Human Factors

Transportation Research Board Annual Meeting 2018 Paper #18-06071

TRIS, TRB, ATRI

Jan 8 2018 11:34AM