M18 motorway (Great Britain) and 12 June 2015. The M18 was originally to be part of the M1, but it was decided to route the M1 towards Leeds instead of Doncaster, and the routing of what would have been the M1 east of Sheffield became the M18. Data from driver location signs are used to provide distance and carriageway identifier information. The location sequence is a continuation of the M1 location sequence. !scope=col|miles !scope=col|km !scope=col abbr="Southbound"|Southbound exits (B carriageway) !scope=col|Junction !scope=col abbr="Northbound"|Northbound exits (A carriageway) !scope=col|Coordinates M18 motorway (Great Britain) The M18 is a motorway in Yorkshire, England. It runs from the east of
M1 motorway Aberford. The new road involved the construction of a series of new junctions, bridges and viaducts to the east of Leeds. When the new section of M1 was completed and opened on 4 February 1999, the Leeds South Eastern Motorway section of the M1 was redesignated as the M621 and the junctions were given new numbers (M621 Junctions 4 to 7). The M1 was extended south from its original starting point at Junction 5 towards London in three stages. The first stage, opened in 1966, took the motorway south-east, parallel to the A41 to meet the A5 at junction 4