Major delays are expected on the West Gate Bridge tomorrow night as road crews complete upgrades on the M1.

All lanes on the bridge will be closed in both directions between 11pm and 4.30am.

VicRoads has warned motorists to allow extra time to complete their journeys.

The work is part of the $1.39 billion Monash-CityLink-West Gate upgrade.

Similar closures will also be in place on October 19, weather permitting.