Chevrons / Oversized Chevrons
Chevrons provide additional emphasis and guidance for drivers.
If spaced properly, chevrons can delineate the curve so that drivers can interpret the sharpness of the curve. Crash modification factors (CMFs) from 0.6 to 1.9 have been reported for chevrons and chevrons and advisory signs.
The Center for Transportation Research and Education (CTRE) at Iowa State University is currently conducting a study that is developing CMFs for chevrons in Iowa.
Several agencies, including the Iowa Department of Transportation (Iowa DOT), have applied a larger chevron size than suggested by the Manual on Uniform Traffic Control Devices (MUTCD).
The idea is that larger chevrons will be more prominent and visible to drivers. These larger chevrons may be particularly useful when sight distance issues exist. However, no studies are available that have studied the effectiveness of oversized chevrons.
More information is provided in this technical brief, Chevrons and Oversized Chevrons, (PDF), which summarizes information about chevrons relevant to Iowa.