Low-cost safety improvements for horizontal curves: a new FHWA publication highlights proven, cost-effective treatments that help reduce run-off-road and roadway departure crashes on rural roads.

In a typical year, more than one-quarter of all fatal highway crashes in the United States--10,427 in 2007, for example--occur on curves. The vast majority of these horizontal curve crashes are roadway departures, accounting for 83 percent of horizontal curve fatalities in 2007. Many countermeasures to address roadway departures are very effective when placed appropriately to address horizontal curves. Therefore, the Federal Highway Administration's (FHWA) focus on reducing roadway departures goes hand in hand with preventing crashes at horizontal curves.

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Most of the fatalities attributed to roadway departures and crashes at horizontal curves occur on rural roads, especially two-lane roads. These roads tend to have unforgiving roadsides and shoulders, and less access to emergency services. Also, motorists are likely to travel on them at higher speeds than the roads are designed to accommodate safely. The magnitude of the rural two-lane highway system and relatively low traffic volumes make significant expenditures for improvements unlikely and pose safety challenges to the agencies that repair and maintain them. Focusing on the horizontal curves on these roadways can help make that process more manageable.

"The bottom line is that 28 percent of the 41,059 people who died on our highways in 2007--more than 11,000 of our family members, friends, and neighbors--died in curve-related crashes," says Division Administrator Tom Smith, of the Federal Highway Administration's (FHWA) West Virginia Division Office, whose State struggles with crashes on horizontal curves.

To reduce the number of deaths and injuries on public roads, FHWA is deploying a variety of low-cost safety improvements, including sign enhancements, barrier delineation, and rumble strips, that can reduce the risk posed by horizontal curves. Many of these low-cost treatments are equally effective in both rural and urban environments. A new publication, Low-Cost Treatments for Horizontal Curve Safety (FHWA-SA-07-002), provides practical information regarding numerous safety treatments that State departments of transportation (DOTs) and local road agencies can deploy without major investments.

Focusing on Horizontal Curve Safety

"If you are going to solve the roadway departure problem, you have to solve the horizontal curve problem," says Frank Julian, a safety engineer on the FHWA Resource Center's Safety and Design Technical Service Team. "The most cost-effective approach to solving roadway departure crashes is to focus on horizontal curves because they make up a small percentage of the road miles but account for one-quarter of all highway fatalities."