According to a Georgia Tech study, the Southeast's rural two-lane highways are the deadliest roads in the nation; one contributing factor may be the pavement drop-offs often found on rural highway edges. Photo: Karen Dixon

Rural two-lane highways are the largest single class of roads in the United States-and they are the deadliest, especially in the Southeast.

From 1996 to 2000, almost one-third of the nation's traffic fatalities occurred in just eight southeastern states; of those, 64% occurred on rural roads, according to a recent Georgia Institute of Technology study.

“The most frequent crashes in the Southeast occurred on rural roads in wooded areas where people ran off the road and hit a tree,” said Georgia Tech associate professor of civil engineering Karen Dixon, who headed the regional study funded by the Federal Highway Administration via the Georgia DOT (GDOT).

With reports from southeastern transportation officials and researchers, the study quantified the top highway safety concerns—including rural roads—in Georgia, South Carolina, Alabama, Mississippi, North Carolina, Kentucky, and Florida. The study also recommended countermeasures, such as lane and shoulder widening.

One of the study's findings lays potential blame for fatal crashes on the 2½- to 5-inch pavement drop-offs often found on rural highway edges.

“Almost half of the non-state-maintained roadway crashes we looked at had an edge drop-off issue,” said Dixon. “We don't know if this caused all of these crashes, but nonetheless, the potential exists for it to be a serious problem.”

Drop-offs develop as roads are repaved and/or soil erodes along the shoulder. Roadside ruts are caused by rural mail carriers who drive with one side of their vehicles on the road and the other on the unpaved shoulder, she added.

To address the drop-off concern, some state and federal transportation agencies are considering changes in roadside edge treatments, such as planting grass and trimming of tree branches along the roads. And a GDOT pilot study is underway to test the durability of a new tapered paved-edge treatment. GDOT began specifying the new tapered paved-edge treatment on a project-specific, rather than general, basis in January.

Countermeasures recommended in the study include widening lanes and shoulders, road alignment improvements, and the addition of advisory speed signs or other speed controls.

The researchers expect to complete this study—funded by the National Research Council—by December 2005.