Factors that Affect Failures of Snowplowable Raised Pavement Markers in Virginia

Abstract

Snowplowable raised pavement markers (SRPMs) are commonly used in Virginia to supplement lane lines on the Interstate and portions of the primary system. Although SRPMs improve lane delineation at night and during inclement weather, they can become damaged or detached from the pavement after prolonged exposure to traffic and snowplows. Before 2009, Virginia had no formal method or schedule to routinely inspect these markers after their installation. In April 2006, a fragment of an SRPM metal casting became dislodged and injured a motorist. In response to this incident, a statewide study was initiated to determine whether systemic problems caused damage or detachment of SRPMs on Virginia's Interstates. Casting condition, reflector condition, epoxy condition, and installation adequacy were inspected on 78 1-mi segments of Interstate pavement that contained SRPMs. The study found that nearly 8% of all SRPM castings inspected were either missing or damaged. Approximately 35% of reflectors inspected were either missing or damaged. An analysis of risk factors showed that total traffic since installation and initial installation adequacy correlated most strongly with casting failures. These data were used to develop an SRPM casting inspection program and schedule that have been adopted by the Virginia Department of Transportation. The study recommends increased training for installers and inspectors.