A roundabout, a rotary and a traffic circle are all, with certain distinctions between them, a type of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.
An intersection or an at-grade junction is a junction where two or more roads converge, diverge, meet or cross at the same height, as opposed to an interchange, which uses bridges or tunnels to separate different roads. Major intersections are often delineated by gores and may be classified by road segments, traffic controls and lane design.
The M50 motorway is a C-shaped orbital motorway in Dublin and the busiest motorway in Ireland. The current route was built in various sections over the course of 27 years, from 1983 to 2010. It begins at Dublin Port, running northward through the Dublin Port Tunnel and along a portion of the Airport Motorway. It then turns west at its junction with the M1, circling the northern, western and southern suburbs of Dublin, before merging with the M11 at Shankill in South East Dublin. The road forms part of European route E01.
An overpass, called an overbridge or flyover in the United Kingdom and some other Commonwealth countries, is a bridge, road, railway or similar structure that is over another road or railway. An overpass and underpass together form a grade separation. Stack interchanges are made up of several overpasses.
The A45 is a major road in England. It runs east from Birmingham past the National Exhibition Centre and the M42, then bypasses Coventry and Rugby, where it briefly merges with the M45 until it continues to Daventry. It then heads to Northampton and Wellingborough before running north of Rushden and Higham Ferrers and terminating at its junction with the A14 in Thrapston.
The Edinburgh City Bypass, designated as A720, is one of the most important trunk roads in Scotland. Circling around the south of Edinburgh, as the equivalent of a ring road for the coastal city, it links together the A1 towards north-east England, the A702 towards north-west England, the M8 through the Central Belt towards Glasgow, the A7 through south-east Scotland and north-west England as well as the A8 leading to the M9 for Stirling and the Queensferry Crossing.
A partial cloverleaf interchange or parclo is a modification of a cloverleaf interchange.
The road hierarchy categorizes roads according to their functions and capacities. While sources differ on the exact nomenclature, the basic hierarchy comprises freeways, arterials, collectors, and local roads. Generally, the functional hierarchy can more or less correspond to the hierarchy of roads by their owner or administrator.
In the field of road transport, an interchange or a grade-separated junction is a road junction that uses grade separations to allow for the movement of traffic between two or more roadways or highways, using a system of interconnecting roadways to permit traffic on at least one of the routes to pass through the junction without interruption from crossing traffic streams. It differs from a standard intersection, where roads cross at grade. Interchanges are almost always used when at least one road is a controlled-access highway or a limited-access divided highway (expressway), though they are sometimes used at junctions between surface streets.
A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms include throughway or thruway and parkway. Some of these may be limited-access highways, although this term can also refer to a class of highways with somewhat less isolation from other traffic.
The Red Cow interchange is a major road junction in west Dublin, Ireland on the M50, meeting the N7 Naas Road at a free-flow grade-separated junction which incorporates a tram line. The N7 route commences at this junction, junction 1 on the N7 and junction 9 on the M50, and the Naas Road from the city centre via Inchicore to the Red Cow interchange comprises part of the R110 and the R810. The junction is the busiest road junction in Ireland. In its original configuration, with traffic signals governing many movements, it frequently had tailbacks several kilometres long on the routes leading to it.
A junction is where two or more roads meet.
A subway, also known as an underpass, is a grade-separated pedestrian crossing which crosses underneath a road or railway in order to entirely separate pedestrians and cyclists from motor or train traffic.
In the field of road transport, a turnaround is a type of junction that allows traffic traveling in one direction on a road to efficiently make a U-turn typically without backing up or making dangerous maneuvers in the middle of the traffic stream. While many junction types permit U-turns, the term turnaround often applies to road junctions built specifically for this purpose.
A roundabout interchange is a type of interchange between a controlled access highway, such as a motorway or freeway, and a minor road. The slip roads to and from the motorway carriageways converge at a single roundabout, which is grade-separated from the motorway lanes with bridges.
Terminology related to road transport—the transport of passengers or goods on paved 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.
