What type of vehicles are lanes marked with a Diamond Symbol reserved for?

Lanes marked with a diamond symbol are reserved for High Occupancy Vehicles (HOV), which typically include vehicles with multiple occupants, such as carpools, buses, and taxis. The purpose of these lanes is to encourage carpooling and reduce traffic congestion by promoting the use of vehicles carrying more than one person.

By designating certain lanes specifically for HOV, transportation authorities aim to maximize the efficiency of road usage, as these vehicles can help carry more people while reducing the number of vehicles on the road. This also supports environmental goals by lowering emissions per passenger.

The other options refer to different categories of vehicles but do not fit the specific purpose of HOV lanes. Commercial vehicles usually operate in general traffic lanes unless specifically indicated, emergency vehicles have their own clearance protocols, and passenger vehicles alone do not qualify for HOV lane use unless they are carrying multiple occupants. Thus, the designation of these lanes is specifically aligned with promoting high occupancy for better traffic flow.