Overview of safety countermeasures for roadway departure crashes

A roadway departure (RwD) crash is defined by the Federal Highway Administration (FHWA) as a crash in which a vehicle crosses an edge line, a centerline, or otherwise leaves the traveled way. Implementation case studies to mitigate RwD crashes were developed based on a comprehensive literature review and input from state and local agencies. RwD safety countermeasures were divided into three major categories: signs, pavement safety, and roadside design. The signs alert drivers to changes in alignment and provide information on what action should be takenencouraging drivers to reduce their speeds. When placed and maintained appropriately, curve signing may reduce the frequency and severity of RwD crashes. Dynamic curve warning systems (DCWSs) detect the speed of approaching vehicles and are programmed to provide drivers exceeding a certain speed threshold with a message, flashing light-emitting diodes (LEDs), or their speed display. Raised pavement markers (RPMs) are often used by transportation agencies as delineation treatments to improve nighttime visibility, particularly in wet pavement conditions. According to AASHTO's Strategic Highway Safety. Centerline rumble strips (CLRS) are a longitudinal safety feature that can be installed at or near the centerline of undivided roadways. A barrier is a device designed to stop or redirect errant vehicles to prevent a more serious crash. Although barriers cannot reduce the total number of crashes, the benefit of cable barriers is that they tend to minimize the severity of injuries by absorbing the impact of the crash and thus have a less severe consequence compared to striking the shielded obstacles.