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.

At the junction with the A803, the road rejoins the older section of the M80 (opened in 1974[4]) and runs for about 1 mile (1.6 km)[5] until it meets the M876 for traffic towards the Kincardine Bridge.

The Kelvin Valley route was not chosen[8] as it would have breached the Antonine Wall and destroyed the Castlecary Roman fort;[9] instead the online upgrade of the A80 through Cumbernauld was selected.

[12] Phase one involved the creation of 8 kilometres (5.0 mi) 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.

The M80 crosses the Glasgow to Edinburgh via Falkirk railway line and Forth and Clyde Canal.