Glossary of road transport terms

Terminology related to road transport—the transport of passengers or goods on paved (or otherwise improved) routes between places—is diverse, with variation between dialects of English. There may also be regional differences within a single country, and some terms differ based on the side of the road traffic drives on. This glossary is an alphabetical listing of road transport terms. 2+1 road A specific category of three-lane road, consisting of two lanes in one direction and one lane in the other, alternating every few kilometres, and separated usually with a steel cable barrier. 2-1 road A specific category of one-lane road being built in Denmark and Sweden, consisting of a single two-way lane with extra wide shoulders for pedestrians and cyclists. 2+2 road A specific type of dual carriageway being built in Ireland, Sweden, and Finland, consisting of two lanes in each direction separated by a steel cable barrier. 3-way junction or 3-way intersection 5-1-1 A transportation and traffic information telephone hotline in some regions of the United States and Canada that was initially designated for road weather information. Access road Advisory speed limit A speed recommendation by a governing body. All-way stop or four-way stop An intersection system where traffic approaching it from all directions is required to stop before proceeding through the intersection. Alternate route or optional route A highway that splits off the mainline and reconnects some distance later. Ambulance A medically equipped vehicle which transports patients to treatment facilities, such as hospitals. Annual average daily traffic (AADT) A measure of total volume of vehicle traffic on a segment of road for a year divided by 365 days to produce an average. Arterial road or arterial thoroughfare A high-capacity urban road designed to deliver traffic at the highest possible level of service. At-grade intersection A junction at which two or more roads cross at the same level or grade. Automobile Automotive vehicle Autonomous vehicle Auxiliary route A highway that supplements a major or mainline highway.