A 49-year-old woman from Churchdown has been air-lifted to hospital with suspected head injuries after she fell from a bridge on the A40 Golden Valley Bypass.
Motorists called for emergency services to the scene between junction 11 with the M5 and the Longlevens roundabout at 12.45pm.
A police spokesman said: "We were called at 12.45pm to reports of a woman falling from a bridge.
"The woman is being taken to Frenchay Hospital with serious injuries, but they are not believed to be life threatening."
Traffic reached as far as Gloucester Road, Cheltenham although the road has been reopened.