West Midlands Ambulance Service said the victim suffered “very serious crush injuries after an incident with a large tracked excavator.”
The accident happened at a site in Corporation Street in Stafford on Tuesday afternoon.
A West Midlands Ambulance Service spokesman said: “On arrival, the man was found to have significant injuries on his right side.
“He had his leg splinted and a pelvic binder put in place before he was airlifted to the major trauma centre at Royal Stoke University Hospital.”