Junctions

The most basic motorway junction is a two-lane flyover with four slip-roads, two on each side of the motorway, to exit or enter. A simple crossroads or roundabout is present on either end of the flyover. A rather large version of a roundabout, using two curved flyovers is sometimes used to present a single large junction for users of the slip-roads or crossing road. The slip roads leading off the motorway are known as “exit slip roads”, those leading onto the motorway as “entry slip roads”. The precise slip road at any junction may be identified by reference to the direction of the carriageway, for example “northbound entry slip”.

The signal-controlled roundabout is often used in these situations and has become very common in Ireland. A far greater degree of complexity is present in Britain with varying types of Spaghetti Junction-style interchanges.

Location and Construction

Major intercity or national routes are often built or upgraded to motorway standard. Motorways are also commonly used for ring roads around cities or bypasses of built-up areas.

In Britain there are plans to improve many motorways as well as to upgrade some roads to motorway status. In Ireland, the National Roads Authority has been connecting main cities with motorways as part of a six-year National Development Plan. The European Union has part-funded many motorway projects in the past, as part of a Trans-European Transport Networks, and there are plans to invest billions of euros in such projects in the next ten years.

One of the most recently constructed motorways in the UK is the M6 Toll, bypassing Birmingham and Wolverhampton, which opened in 2004 and is the only completely toll motorway in England. There are tolled sections of motorway on the M4 and M48, where they cross the River Severn at the Severn crossings. Although the crossing of the River Thames east of London is tolled, the bridge and tunnels themselves are officially designated to permit usage by non-motorway traffic.

Unit 11 Freeway

This stylized drawing of an overpass is used to represent a freeway in many countries.

A freeway (also motorway or expressway) is a type of highway that is designed for safer high-speed operation of motor vehicles through the elimination of at-grade intersections. This is accomplished by imposing full control of access from adjacent properties and eliminating all cross traffic with grade separations and interchanges, and no railroad crossings. Such highways are usually divided with at least two lanes in each direction. Because traffic never crosses at-grade, there are generally no traffic lights or stop signs. The word freeway is also used to describe a highway without tolls.

Note: Expressway has other meanings, and motorway typically applies only to those roads designated as motorways by the national highway agency. Thus this article will primarily use the term freeway for clarity and conciseness. The terms “controlled access” and “limited access” are also used, but both terms can also apply to arterial roads with partial control of access.

Despite the name, a freeway can be a toll road.