The M80 is a motorway in central Scotland, running through Glasgow, North Lanarkshire, Falkirk and Stirling and links the M8, the M73 and M9 motorways. Following completion in 2011, this road is 25 miles (40 km) long. From 1992 – 2011, the road was in two sections; the southern section, Glasgow to Stepps and the northern section Haggs to Stirling. A connecting Stepps to Haggs section was completed in September 2011. The new section partially opened in February 2011 when the Moodiesburn bypass opened to traffic, extending the southern section to Mollinsburn. The A80 between Mollinsburn and Auchenkilns was widened to three-lane carriageway in each direction, and the section from Auchenkilns to Haggs remains 2 lane, now with hard shoulders.
The M80 was constructed in three stages: M8 to Stepps (opened 1992), Stepps to Haggs (opened 2011), and Haggs to the Pirnhall (opened 1974).
This section of road was originally envisioned during the M8's construction in the 1960s, but was not realised until 1992), also known as the 'Stepps Bypass' begins at M8 Junction 13 in the Glasgow suburb of Blochairn. It runs to the north of Stepps, under the Cumbernauld Railway Line with exits for Bishopbriggs, Lenzie and Kirkintilloch, where it continues onto the new section, completed in 2011.
The Stepps to Haggs section was completed in September 2011, completing the M80 route. A short section of offline upgrade takes the route from the former terminus at Junction 3 (Stepps), to a new Junction with the M73. After this, the route follows an on-line upgrade of the former A80 through Cumbernauld. It is mainly 2-lane dual carriageway.
At the junction with the A803, the road rejoins the older section of the M80 (opened in 1974) and runs for about 1 mile (1.6 km) until it meets the M876 for traffic towards the Kincardine Bridge. The M80 continues north passing to the west of Denny and after 5 miles (8.0 km) meets a junction with the A91 (the same roundabout interchange also hosts Stirling Services) and then merges into the M9 just outside Stirling at Bannockburn.
The M80 Stepps to Haggs Completion Project connected the two halves of the current motorway via an online upgrade of the existing A80, passing through Cumbernauld and Auchenkilns, and the offline creation of new motorway from Stepps to Mollinsburn. Although various plans were considered from the 1970s to 1990s to connect the two sections of motorway, it was not until 2003 that a definitive timeline for proposing, developing and executing a completion plan was announced.
Two routes were proposed for development: the so-called Kelvin Valley route, which would create a bypass to the north of the existing line of the A80, and the "online" upgrade of the existing A80 to motorway grade. In October 2005, the project was put to a public inquiry, which ended in August 2006. The Kelvin Valley route was not chosen as it would have breached the Antonine Wall and destroyed the Castlecary Roman fort; instead the online upgrade of the A80 through Cumbernauld was selected.
Originally budgeted to cost £130m to £180m, but as of August 2010 was estimated to cost £320m, preparatory works were started in November 2008, and construction work began in January 2009. The project was completed in September 2011.
The upgrade plans were set into three discrete phases. Phase one involved the creation of 8 kilometres of road from Stepps, routing north of Muirhead, Moodiesburn and Chryston, and meeting the line of the existing A80 at Mollinsburn with the construction of a new interchange, connecting the M80 with the M73 and the western section of the A80. Phase two required the online upgrade of the A80 between Mollinsburn and Auchenkilns, with the attendant upgrade of adjoining on-slip and off-slip roads, meeting the Auchenkilns Interchange. The interchange was opened in November 2005 after the online grade separation of the Auchenkilns Roundabout from the line of the dual carriageway created a grade separated dumbbell interchange, linking the A80 (and subsequently the M80) with the A73 and B8048. Phase three saw the A80 upgraded online from Auchenkilns to the Haggs Interchange east of Cumbernauld – also seeing some junctions being upgraded, but with some being removed – completing the connection of the western M80 to the eastern M80, and connecting to the M876 and M9 motorways. The M80 crosses the Glasgow to Edinburgh via Falkirk railway line and Forth and Clyde Canal.