An advisory speed may be desirable where a depression or bump in the road profile is sufficiently abrupt to create a hazardous condition, cause discomfort to passengers, cause a shifting in cargo, or deflect a vehicle from its true course when crossed at speeds prevailing on the approaches.

The speed to be posted for dips or bumps should be determined by trial runs. It should be the highest speed that will enable a vehicle to travel over the dip or bump without considerable discomfort to passengers, without causing a shifting of cargo, or without causing a deflection of a vehicle from its true course.