Specialty Warning Signs
There is a hierarchy of signs that must be present within any roadway; Regulatory, Warning, and Guide signs.
Agencies must strike the right balance and only install signs that are necessary and effective. Warning signs inform drivers of unexpected changes in the roadway and dangers that are not readily apparent. As such warning signs are most effective if they warn drivers of hazards that are always present, e.g. sharp curves or low clearance heights at a bridge crossing. Specialty warning signs that warn of infrequent conditions or general possibilities such as deer crossings, slippery road when wet, or children at play signs, are routinely ignored by drivers. Specialty warning signs can also create the false impression that areas without warning signs don’t have hazards. This inconsistent driver behavior creates an unsafe environment for motorists and pedestrians.
This video was produced by the Minnesota Local Road Research Board, and explains which warning signs are necessary and effective, and which may be counterproductive.