The road plan published in February 1964 by the Minister of Development, William Craig, showed two circles at Belfast and Craigavon. These indicated that there would be urban motorway systems in the old and new cities.
The M12 spur at the Ballynacor junction on the M1 serves traffic to and from Craigavon and the Armagh area. Originally it was connected to the old B2 at Cam. This portion came into use on 27 November 1967 with the adjoining section of the M1.
Since then the road systems towards the new Craigavon town centre and towards Portadown have been developed as the "Northway" scheme. Work on the various stages, now single carriageway, was done between 1968 and 1975.
The portion near the new Portadown railway station, known then as the "Portadown Urban Motorway", was opened on 9 June 1970 by the Governor, Lord Grey. The schemes were designed and supervised by the Commission staff, and the bridges were designed by Freeman Fox under Kerensky and by the Commission staff.
The M1/M12 contract in 1967 included another bridge over the motorway for a future link to the Craigavon area from the North West. This link and the necessary motorway slip roads were constructed in 1991 by the Craigavon Division of the Roads Service. The Contractor was WAM (GB).
Another junction had been added to the M1 in 1988 when slip roads to and from Belfast were added at Black's Road near Dunmurry. The contract was carried out by Graham.