Final answer:
A low underpass sign indicates that the clearance height of the underpass is low and vehicles with a higher height may not be able to pass through safely.
Step-by-step explanation:
A low underpass sign indicates that the clearance height of the underpass is low and vehicles with a higher height may not be able to pass through safely. It serves as a warning to drivers to be cautious and avoid attempting to drive vehicles that are taller than the specified height limit under the underpass.
For example, if a low underpass sign states a clearance height of 10 feet, it means that any vehicle taller than 10 feet should find an alternative route to avoid potential damage or accidents.
Low underpass signs are an important aspect of road safety to prevent accidents and ensure the smooth flow of traffic.