MOTORISTS will need to allow extra time if they're travelling into the city from the northern suburbs after an earlier accident caused gridlock traffic on the Gateway Motorway between Nudgee and Bald Hills.

A truck and motorbike collided in the southbound lanes just before 8am, leaving a man with leg injuries but in a stable condition.

Drivers are being told to allow more than an hour a half to get through a 14 kilometre stretch of the highway.

The morning commute is also congested in the south with heavy traffic on the M1 at Pimpama and Eight Mile Plains and again through Woolloongabba.