Work on the new $13.4M Carlton water main down Canning Street starts on Monday, and the first detour will be in place from 9:30am that morning.
The first worksite is at Elgin Street, and as a result riders will be directed across to Rathdowne Street via Palmerston Street.
Messaging boards to alert riders will be located at several points upstream.
Only city-bound riders will be detoured as the new main will be under the road on the east side of Canning Street.
The first stage of the project involves construction of the water main under Elgin Street.
Two tunnel shafts will be excavated on Canning Street; one on each side of Elgin Street at the traffic lights, to enable tunnelling under Elgin Street.
Once tunnel boring is completed, the first section of the new water pipe under Canning Street will be installed, making way for open trench installation of the pipe along the remainder of Canning Street.
In order for works to be carried out in a safe environment, temporary full road closures in the southbound lane of Canning Street between Elgin and Barkly streets will come into effect.
The first stage is expected to take 4-6 weeks.
The 2.3km main will replace the fragile main currently under Nicholson Street, installed in 1878. Increased traffic density and future tram stop upgrades on Nicholson Street necessitated the relocation of the pipeline.
To be completed by the middle of next year, the City West Water project will guarantee water supply for residential and commercial properties across Carlton, Carlton North and Melbourne CBD.
Further details can be found at citywestwater.com.au/canningst.