What is a clear definition of a “Clear Zone”?
The “Clear Zone” is the area where a vehicle leaving the road can travel without conflict. The specific size of the clear zone is typically limited to the Right of Way the municipality maintains or has been designated along a roadway or street. Signs are put up by the municipality are typically within that ROW and are therefore the responsibility of the municipality. The use of breakaway hardware is required if the sign post is not otherwise protected by a barrier. Breakaway hardware and the clear zone are intended for the safety of the public and to reduce the potential of liability to the municipality.
The MUTCD defines the Clear Zone in Section 1A.13 as:
The total roadside border area, starting at the edge of the traveled way, that is available for an errant driver to stop or regain control of a vehicle. This area might consist of a shoulder, a recoverable slope, and/or a non-recoverable, traversable slope with a clear run-out area at its toe.
And again in Section 2A.16 as:
07 The clear zone is the total roadside border area, starting at the edge of the traveled way, available for use by errant vehicles. The width of the clear zone is dependent upon traffic volumes, speeds, and roadside geometry.
Additional information can be found in AASHTO’s “Roadside Design Guide” (see Section 1A.11).