Melbourne drivers have been told to expect delays as the left turn from St Kilda Road into Flinders Street has closed.
To help with the constructions of the new Metro Tunnel, the turn will now be closed for up to 20 months.
The left turn ban is in place to allow trucks into the work area near the new Town Hall station.
Motorists are now being told to use Kings Way and Southbank Boulevard or turn right from St Kilda Road into Flinders Street and detour via Russell and Collins streets.
The Flinders Street pedestrian crossing between St Paul’s Cathedral and Federation Square has already closed and there is an alternative near Hosier Lane.
“The Department of Transport thanks motorists for their patience while these important works take place,” a statement from the Department of Transport said.
The tunnel is expected to open in 2025.