Dual carriageway

A dual carriageway in Great Britain.

A dual carriageway (British English) or divided highway (American English) is a type of road. It is an important route that usually carries long-distance traffic.

A dual carriageway has four lanes (2 lanes each side), and is always separated by a man-made barrier or strip of land.

Dual carriageways have no hard shoulder. A hard shoulder is an area at the side of a road where drivers can stop if there is a serious problem, a breakdown for example.^[1]^[2]

Dual Carriageway Media

Map by Cassius Ahenobarbus, zoomed in to show the Via Portuensis, with the dual carriageway splitting close to the city of Rome. This is a very early (perhaps the first) example of a dual carriageway.
Autostrada A20 runs through the island of Sicily in Italy linking Palermo to Messina
Clara Barton Parkway outside Washington, D.C.
Jersey barriers may be used to separate the carriageways where the space is narrow. See this example near Málaga, Spain. There is also a bus stop in the bottom-right corner of the picture; it would not exist in a motorway.
Diagram of types of road in the UK
Sign informing motorists of an upcoming section of dual carriageway in Seacroft, Leeds
A typical modern Irish dual carriageway (opened 2004) along the N11, south of Newtownmountkennedy. On motorways, the yellow hard shoulder markings are unbroken.
An example of a 2+2 dual-carriageway in Ireland. This type is similar to many found in the UK.
Die Bundesstraße 6 bei Harlingerode, Westblick Richtung Goslar/Immenrode, Dezember 2018. Im Hintergrund der Windpark Harlingerode.