Development of Clear Recovery Area Guidelines
The clear zone concept for roadside design emerged in the mid-1960s as a single distance for
lateral clearance that reduced the likelihood of an errant vehicle striking a roadside obstacle.
Subsequent recovery area guidance that evolved over the next two decades provided a variable
distance expressed in terms of traffic volume, design speed, sideslope, and other roadway and
roadside factors.
NCHRP Research Report 1097: Development of Clear Recovery Area Guidelines,
from TRB's National Cooperative Highway Research Program,
develops updated guidelines for roadside clear zones expressed in terms of key roadway
and roadside design parameters. These updated guidelines can aid designers in better understanding the risk associated with roadside encroachments while recognizing and working within the associated design constraints.
This Summary Last Modified On: 3/8/2024