Content references source material no longer available at its original location.
Sequential, dynamic curve warning guidance systems can reduce reduce reported crashes by up to 77 percent.

Agencies utilize intelligent warning systems to help mitigate crash fatalities in rural areas.

Date Posted
03/31/2015
Identifier
2015-B00989
TwitterLinkedInFacebook

Ahead of the Curve

Summary Information

Statistical analysis from the National Highway Transportation Safety Administration (NHTSA) finds that nearly 60 percent of all fatal crashes occur on rural roads. With most of these crashes resulting from roadway departures, the primary goal is to help keep vehicles in their lane. This article in Thinking Highways discusses how to mitigate the occurrence of road departures by taking a systematic approach to deploying technological strategies in a cost effective manner.

There are several types of lane departure strategies to provide guidance to drivers entering a horizontal curve. These include low-cost solutions such as guardrails and rumble strips; but there are other medium and higher cost solutions using technology that can help to mitigate crashes significantly. A medium cost option includes providing LED enhanced chevrons that draw attention not only to the sign, but also to the extent of the curve along the roadway. Higher cost options include the use of Dynamic Curve Warning Systems (DCWS) that typically combine a radar and/or classification device with a Dynamic Message Sign. With these devices, only drivers with excessive speeding and thus a high rollover potential are flashed a message to slow down to a recommended speed. More sophisticated DCWS can also factor in weight, live-load, non-live load and configuration in calculating the potential for rollover. An even newer solution involves signs with sequentially flashing LED’s that are operated by a wireless controller to flash with the speed of traffic and the geometrics of the curve.

Findings:
  • In an evaluation of the safety effectiveness of various horizontal curve delineation treatments in Italy, sequential flashing beacons on chevrons and curve warning signs were shown to decrease the number of reported crashes by 77 percent when compared to the expected number derived from an Empirical Bayes analysis.
  • DCWS are used in areas with high accident rates to reduce the overall number and severity of crashes.
Goal Areas
Deployment Locations