Where these drivers went wrong.

Morena, D.A. & Leix, T.J.

Although crashes caused by wrong-way drivers are rare, they kill or severely injure drivers and passengers at a much greater rate (per crash) than other types of freeway incidents. This paper describes a study conducted by the Federal Highway Administration and the Michigan Department of Transportation (MDOT) regarding wrong-way crashes on freeways. Researchers analysed 110 wrong-way crashes that occurred on the Michigan freeway system from 2005 to 2009. The researchers restricted their study to vehicles that were known or presumed to have entered the freeway system by travelling the wrong direction on an exit ramp. Findings show that some potential for driver confusion leading to wrong-way entry exists across the entire population, but is amplified in drivers impaired by alcohol or drugs, older drivers and drivers at night. The severity of a wrong-way crash was linked to how far the wrong-way vehicle progressed onto the system. A partial cloverleaf interchange provided the wrong-way ramp entry for 60% of the crashes for which the wrong-way entry point was known. The partial cloverleaf has a feature that appears to be the source of confusion leading to wrong-way freeway entry: a pair of freeway exit/entrance ramps that are adjacent and parallel to each other, and typically meet the crossroad at or near a 90-degree angle. The wrong-way entry mode for a driver is to turn onto the freeway exit ramp, thinking that they are entering onto the freeway entrance ramp. Most of the engineering solutions that can mitigate this problem involve positive cues to showcase the entrance ramp, and negative cues that make the exit ramp appear uninviting. Based on these findings, MDOT staff identified 161 interchanges that exhibit the suspect feature of partial cloverleaf. These interchanges are being targeted for systematic installation of low-cost countermeasures over the next 5 years. The countermeasures include: lowering the bottom height of DO NOT ENTER and WRONG WAY signs; installing reflective sheeting on the sign supports of these signs; placing stop bars at exit ramps; installing wrong-way pavement marking arrows at exit ramps; installing pavement marking extensions that will guide crossroad left-turning traffic past the exit ramp and safely onto the entrance ramp; painting the island between the exit and entrance ramp for a sufficient distance up the ramp; and placing red delineators along the exit ramp to discourage wrong-way vehicles that are headed up the exit ramp. MDOT has identified the first two of these countermeasures as being cost effective for all ramps, regardless of type. These countermeasures will be installed at the non-targeted interchanges as they come up for routine work. (Author/publisher)


20121826 ST [electronic version only]

Public Roads, Vol. 75 (2012), No. 6 (May/June), p. 33-41; FHWA-HRT-12-004

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