Don't leave it to the last minute to rush out the door and drive to work on Wednesday.

Motorists face long commutes during morning peak hour as CityLink starts work widening the Tullamarine Freeway.

CityLink is adding an extra lane each way on the Bolte Bridge and on the exit ramp that takes traffic to the West Gate Freeway and through to the Burnley Tunnel.

"Drivers travelling into the city in the morning peak should expect their trip to take longer than usual," a CityLink spokesman said.

The spokesman said VicRoads would update on expected travel times throughout the morning.