Costain shut down a section of the M6 smart motorway widening project after a 13 tonne excavator was upended in the central reservation last Friday.
The excavator operator is understood to have escaped without injury but was shaken after his machine toppled backwards into a central reservation drainage trench on the Costain project just north of junction 21A.
Thomas Plant had the short radius excavator on hire, which was being used by Manchester drainage contractor SGC Civil Engineering for drainage works in the central reservation area.
Main contractor Costain is carrying out an investigation into the incident.