@article{ref1,
title="Safety of U-turns at unsignalized median openings: Some research findings",
journal="Transportation research record",
year="2005",
author="Levinson, HS and Potts, IB and Harwood, Douglas W. and Gluck, Jerome S. and Torbic, DJ",
volume="1912",
number="",
pages="72-81",
abstract="Many state and local transportation agencies install nontraversable medians on multilane highways to improve safety and travel times and to manage local access better. While nontraversable medians restrict direct left-turn access to and from adjacent developments, traffic destined for these locations must use alternate routes, some of which may involve making U-turns at nearby median openings-a movement often referred to as an indirect left turn. Until recently, the safety effects of increased U-turn volumes have been largely unknown. NCHRP Project 17-21, Safety of U-Turns at unsignalized Median Openings, documented the safety performance and operational effects of U-turns at median openings. This paper presents the key findings from that research. It presents a summary of key literature and current highway agency practice related to median openings, a detailed classification scheme for median openings, and a summary of the results of comprehensive field studies. The research results indicate that access management strategies that increase U-turn volumes at unsignalized median openings can be used safely and effectively. Analysis of accident data found that accidents related to U-turn and left-turn maneuvers at unsignalized median openings occur infrequently. In urban arterial corridors, unsignalized median openings experienced an average of 0.41 U-turn-plus-left-turn accidents per median opening per year. In rural arterial corridors, unsignalized median openings experienced an average of 0.20 U-turn-plus-left-turn accidents per median opening per year. On the basis of these limited accident frequencies, there is no indication that U-turns at unsignalized median openings are a major safety concern.<p />",
language="en",
issn="0361-1981",
doi="",
url="http://dx.doi.org/"
}