Police closed one lane of the anti-clockwise M60 at Junction 10, Barton high-level bridge, after a man was spotted on the wrong side of the railings.
As of 4.45pm, North West Motorway Police were on scene and dealing with the incident.
Traffic is backed up all the way to Junction 15 at the Swinton interchange for the M61.
A 37-year-old woman tragically lost her life at Barton in June when she fell from the bridge.
Drivers report that there are also long queues forming on the M602 between Eccles and Manchester city centre after an earlier accident on the M62 near Birchwood.