The line of the M1 in Belfast had been planned for a road since 1946 as the Southern Approach Road, though there were some disagreements on the route. County planners in Armagh had also been working on plans to rebuild the then T3 trunk road which suffered from poor alignments, limited speed limits and was of failing construction, some work on which had been undertaken between 1955 and 1957. These two plans were eventually upgraded into plans for the M1 by 1958. Construction began 1957 on the first bridge and subsequently the first section of the motorway. In 1964, the Northern Ireland Government announced plans for an extensive route of motorways which saw the M1 now planned to go to Dungannon. The M1 is the only motorway in Northern Ireland completed to its full planned length The road was constructed in stages between 1962 and 1968: Prior to the opening the RUC traffic division ran a publicity campaign to educate drivers on how to drive on a motorway. At the end of 1965 UK Transport Minister Tom Fraser and his successor Barbara Castle imposed a blanket 70 mph speed limit on motorways in Great Britain, but the recently constructed Northern Ireland M1 remained free of a blanket speed limit for several years.
Several junctions were omitted from the original construction, as these were for future planned motorways, some of these have now been used for other road plans:
Junction 3 was opened in 1988.
Junction 8 was opened in 2003. This provides access to the A1 in both directions, whilst junction 7 had its slip roads facing west closed. Junction 8 had originally been planned for a different location for the M11 motorway to relieve the A1 towards the border with the Republic of Ireland.
The M1 is straight and flat on the stretch between Junctions 9 and 10 and on the stretch between Junctions 12 and 13, and an urban myth exists claiming that these were to be used as supplementary runways by the United States Air Force in the event of a major conflict with the Soviet Union. By the mid 2000s the M1 in Belfast had high traffic flows at peak times and suffered from congestion. To relieve this work commenced early in 2006 to replace the roundabout at junction 1 with a fully grade separated junction through which the M1 now flows directly onto the A12 Westlink dual-carriageway. As part of the scheme, the M1 was widened from two to three lanes in each direction between Junctions 1 and 2 along with part of the Westlink. Work was also carried out on the A4 which begins at the terminus of the M1 between Dungannon to Ballygawley was upgraded to dual carriageway standard, opening in November 2010. In 2011 the government announced plans for two service areas in each direction between junction 3 and junction 6 near Ballyskeagh. These service stations are the first motorway service stations in Northern Ireland. They include petrol stations and restaurant facilities. Construction on the westbound service area began in November 2013 and was opened on 10 March 2016. Work on the eastbound service area began in April 2016 and was opened on 2 February 2017.
Future improvements
In 2006, the government announced plans for a £45m flyover link directly to and from the A1 and M1 eastbound. Construction was initially estimated to take place between 2010 and 2015. As of June 2016, the scheme has no projected completion date. The government also have plans to add west facing slip roads at junction 3. Junction 3 opened in 1988 with only east facing slip roads. Construction on the west facing slip roads is subject to future budget settlements.