The Influence of Horizontal Curve on Traffic Crashes in Ohio

<span>Horizontal curves (HCs) - roadways where the direction of the alignment changes horizontally are generally well known as safety-critical aspects about the highway systems. It has been found that crashing rates on horizontal curves are significantly greater than on tangent (straight) segments with frequently fatal crashing rates three times higher. The article is an evaluation of the role of horizontal curves in traffic crashes, which has applicability to the Ohio road system. The analysis uses results of the recent international and domestic studies on geometry (curve radius, curve length, superelevation, transition design), driver and traffic conditions (speed, traffic volume), and environmental factors, which lead to high rates and seriousness of the crashes. Specifically, smaller radius curves, as well as short and sharp curves are always linked to a higher risk of crash and more serious consequences. Strategies which can be used as countermeasures like realignment, increased signage, and cheap surface treatment are also reviewed. The research presents a methodology - with negative-binomial regression or Safety Performance Functions (SPFs) - of modeling crash frequency on curves segments, which can be used to evaluate risk on the crashes in Ohio (e.g., Ohio Department of Public Safety crash database). Lastly, the article suggests specific interventions (e.g., curve realignment, rumble strip additions, advance warning signs) to eliminate high risk horizontal curves in Ohio and suggests that further studies that use both geometric curve and crash records to come up with localized Crash Modification Factors (CMFs).</span>