HOV lanes are marked with what type of symbol?

HOV lanes, or High-Occupancy Vehicle lanes, are designated for vehicles carrying multiple passengers to encourage carpooling and reduce traffic congestion. These lanes are marked with a diamond symbol. The diamond indicates that the lane is restricted for use by eligible vehicles, which typically include those carrying two or more passengers, confirming the lane's purpose of promoting shared-use transportation.

The diamond symbol is highly recognizable and provides a clear visual cue to drivers that they need to check the occupancy of their vehicle before using that lane. This clear distinction helps manage traffic flow and supports the overall goal of reducing the number of single-occupant vehicles on the road. The other shapes mentioned, such as circles, squares, and triangles, do not accurately represent HOV lanes and are instead used for different traffic signs and designations which serve other purposes in road signage and traffic management.