01698337

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A continuous green T-intersection (CGT) is an innovative intersection that could improve the through traffic capacity by allowing major-leg vehicles on the top side of T-intersection to pass through without stopping. Recently, traffic engineers decided to stop CGT operations at several T-intersections in Florida because of traffic safety concerns, conversion to four-legged intersection, pedestrians’ demand, and non-compliance with the latest Manual on Uniform Traffic Control Devices. In this study, safety effects of recent conversions of CGTs back to conventional T-intersections in Florida are explored. A before-and-after study with the comparison group method are adopted. The results indicate significant reductions in total, fatal-and-injury, rear-end, and CGT-related crashes by 40% to 60% after the conversion. In order to validate the results, a cross-sectional analysis was conducted with new data from four states. The results are consistent for total, fatal-and-injury, and CGT-related crashes with those from the before-and-after study. The results also show that crashes at CGTs could be minimized by providing a physical separation between the acceleration lane for the merging vehicles and the CGT through lane, along with other factors. Because Florida’s T-intersections that were converted back to the conventional design from CGT had no physical separation, and the results showed a significant safety improvement after the conversion. Therefore, the decision to stop CGT operations at the Florida’s study sites was supported from the safety aspect. The study concluded that safety at CGTs could be a concern compared to non-CGTs; however, it could be significantly improved by providing appropriate countermeasures.

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

19-00233

English

8p

2019

Transportation Research Board 98th Annual Meeting

Digital/other

Figures; References (13) ; Tables

Crash causes; Highway safety; Pedestrians; Risk assessment; Signalized intersections; T intersections; Traffic flow; Traffic signal timing

Florida

Highways; Operations and Traffic Management; Safety and Human Factors

Transportation Research Board Annual Meeting 2019 Paper #19-00233

TRIS, TRB, ATRI

Dec 7 2018 9:52AM