The Ipswich Motorway has re-opened after being closed outbound for hours after a car flipped at Wacol on Saturday afternoon.

The driver was critically injured in the crash, just before 4pm, approaching the Brisbane Road off ramp.

Emergency services respond to the crash at Wacol. Credit:Nine News Brisbane.

Shortly after 9pm, police announced the highway had re-opened but warned drivers to expect delays.

A police spokeswoman said the car flipped but there did not appear to be any other vehicles involved.

All four westbound lanes of the motorway were closed and motorists were urged to avoid the area.