@article{ref1,
title="Safety effects of roundabout conversions in Carmel, Indiana, the Roundabout City",
journal="Journal of safety research",
year="2022",
author="Wang, Jin and Cicchino, Jessica B.",
volume="82",
number="",
pages="159-165",
abstract="INTRODUCTION: Roundabouts are a proven safety countermeasure for intersection safety. This study examined the safety effects of roundabout conversions in Carmel, Indiana, also known as the &quot;Roundabout City.&quot; Doing so is of particular interest because Carmel has a high density of roundabouts and its drivers understand their effectiveness and are familiar with navigating them. This study also adds to the current state of knowledge about innovative double-teardrop roundabouts (i.e., linked roundabouts with teardrop-shaped central islands). <br><br>METHOD: Negative binomial models accounting for correlation within site pairs were applied to evaluate the safety effects of converting conventional intersections to roundabouts on total crashes, injury crashes, and property-damage-only (PDO) crashes between study sites and control sites for different roundabout types (single-lane, multi-lane, and double-teardrop). We compared crash data from a 2-year period before the installation of the roundabouts with the 2-year period after the conversions. <br><br>RESULTS: Injury crashes were 47% lower than what would have been expected without the roundabout conversions. The effects were strongest at the double-teardrop roundabouts, where injury crashes were significantly reduced by 84% and total crashes by 63%. Single-lane roundabouts experienced significant decreases of 51% in total crashes and 50% in PDO crashes (and a nonsignificant decrease of 50% in injury crashes). Multi-lane roundabouts were associated with increases in total and PDO crashes but a 15% decrease in injury crashes, though all were nonsignificant. <br><br>CONCLUSIONS: Overall, the City of Carmel's roundabout program is associated with reductions in injury crashes, which indicates improvements to safety. Single-lane and double-teardrop roundabouts are associated with improvements in the occurrence and severity of crashes.   PRACTICAL APPLICATIONS: Double-teardrop roundabouts should be considered for installation at interchange terminals to improve highway safety.<p /> <p>Language: en</p>",
language="en",
issn="0022-4375",
doi="10.1016/j.jsr.2022.05.007",
url="http://dx.doi.org/10.1016/j.jsr.2022.05.007"
}