DANGEROUS ROADS
Excerpts taken from article in the American Association of Justice Trial Magazine
11,000 IS THE NUMBER OF PEOPLE INJURED ANNUALLY FROM CRASHES RELATED TO UNSAFE PAVEMENT EDGES
How safe are American highways? Not very, according to the American Society of Civil Engineers. On their latest report card, America’s highway infrastructure received a “D+.” Highway shoulders are especially vulnerable to defects when poorly maintained, and these defects can cause drivers to go off the road. A few central issues comes up routinely in these cases, including drop-off height and angle, and inadequate pavement edge markings and signs.
When rebuilding roads and highways, contractors routinely ignore local, state, and national safety standards and leave unsafe drop-offs between the edge of the roadway pavement and the shoulder, or drop-offs between the lanes. Erosion and excessive wear can also cause drop-offs as the shoulder material migrates away from the pavement edge.
These pavement edge drop-offs are dangerous. The height difference between the two surfaces can decrease vehicle stability and hinder a driver’s ability to handle a vehicle. As the vehicle leaves the travel lane, the right tire slips off the pavement and becomes wedged or restricted by the pavement edge. Drivers are often surprised and instinctively try to return to the travel lane, causing the tires to “scrub” against the pavement edge, which prevents the vehicle from climbing back onto the pavement. At this point, friction built up from the tires often puts the vehicle into a sudden twist, which causes the driver to lose control and fishtail or cross the centerline and collide with oncoming traffic.
Crashes related to unsafe pavement edges injure about 11,000 people and kill about 160 people annually, costing $1.2 billion per year. States bear most of this cost-some of the most common tort liability suits filed against state agencies involve pavement edge drop-offs. Contractors responsible for designing, constructing, and maintain roadways can also face liability for unsafe pavement edge drop-offs.
Standards and guidelines
There are no mandatory national standards that require a specific level of pavement edge maintenance, but several federal agencies provide some guidance, including the Federal Highway Administration (FHWA), American Association of State Highway and Transportation Officials (AASHTO), and the National Cooperative Highway Research Program. Studies and reports suggest threshold drop-off heights that should prompt highway departments to act, but there is no consensus among national organizations as to the appropriate drop-off shape or the specific drop-off level that constitutes a potential hazard.
AASHTO suggests that “no vertical drop-off greater than 50 mm (approximately 2 in.) should occur” and that “pavement edge drop-offs greater than 75mm (approximately 3 in.)… Should not be left overnight.” State standards for an edge drop-off height that is considered unacceptable vary, but typically range from 1.5 to 3 inches. State regulations often require more extensive traffic control, signs, and warning devices if a drop-off reaches a certain threshold.
Angled drop-offs, as opposed to vertical edge drop-offs, can drastically reduce the risk of uneven highway surfaces and allow drivers a chance to safely reenter the highway. The FHWA recommends shaping pavement edges to 30 degrees. Edge-shaping treatments are relatively inexpensive, extend pavement life, and typically require less than 1 percent additional asphalt.
Highway shoulders are intended to serve as safety devices, protecting the traveling public. The entities that own, construct, and maintain our nation’s highways have a responsibility to ensure that shoulders perform as intended.