Thousands of commuters on some of Melbourne's busiest tram lines will be forced onto replacement buses for two weeks as the Metro Tunnel enters a new phase of construction.

Commuters can expect to be hit by delays until October 27 as eight tram routes along St Kilda Road are replaced by buses.

Commuters waiting for tram replacement buses along St Kilda Road, near the Shrine of Remembrance. Credit:Scott McNaughton

St Kilda Road is one of the busiest corridors on Melbourne’s tram network with thousands of passengers travelling along it every day.

The Department of Transport said buses would match tram frequency over five stops and that the Metro Tunnel works, which started on Sunday, had been carefully coordinated to minimise disruptions to passengers, motorists and pedestrians.