Traffic is banked up heading towards the airport after a collision and car roll-over on the Tullamarine Freeway this morning.

The left lane of the Freeway is closed outbound at the Western Ring Rd after a Mercedes collided with another vehicle about 10.15am.

Delays are pushing back to the Calder Freeway.

The crash caused the car to flip and land on its roof near the Ring Road overpass, just past Essendon Airport.

Emergency Services are on scene and VicRoads have urged drivers to allow extra time and keep right past the scene.

The condition of the occupants is not yet known.