Construction of the second city crossing in Manchester's expanding tram network will begin on Monday 6 January.
Metrolink says the new city centre line will provide greater capacity and resilience across the network.
The three-year construction programme will begin in Corporation Street, between Withy Grove and Market Street, where gas pipes, electricity and phone cables will be diverted away from the new tramway.
This will see trenches dug so new ducting can be laid for pipes and cables. Localised road closures and diversions will be put in place but access to businesses in the area will be maintained at all times. The programme is expected to be completed in early 2017, including redeveloped Deansgate-Castlefield and Manchester Victoria stops.
Once completed, the line will begin in Lower Mosley Street and run through St Peter's Square, before turning down Princess Street and then heading along Cross Street and Corporation Street before re-joining the existing Metrolink line outside Victoria station.
As part of the project, new stops will be built in Exchange Square and St Peter's Square.
Cllr Andrew Fender, chairman of the TfGM Committee, said: "This will be the starter pistol for a marathon civil engineering project that is an essential part of the Metrolink expansion.
"The Second City Crossing (2CC) will increase the capacity, flexibility and reliability of all of the network's new lines and enable them to operate to their fullest.
"As such, it will play a vital role in helping to build a strong and prosperous economy for Greater Manchester."
Powers to install the second Metrolink route were formally approved by the government in November following a public inquiry held earlier this year and a major public consultation in 2011.
Peter Cushing, TfGM's Metrolink director, said: "It's a significant piece of work and not without its challenges, but we have learnt a huge amount successfully delivering new street-running lines to Ashton, Oldham and Rochdale town centres and to Wythenshawe and Manchester Airport and we will be drawing on this experience to keep disruption to an absolute minimum.
"We have also established strong links with businesses in the city and I'd encourage anyone who hasn't already done so to get in touch so we can keep them up to speed over the life of this project and beyond."