The environmental surveys will be carried out through to the autumn
A number of environmental surveys are to be carried out in Greater Manchester along the routes where the Metrolink network is to be extended.
Experts will check to see if protected species live along the new routes.
They will also record which trees and shrubs will need to be replaced and examine air and noise quality.
In addition, specialists will check traffic levels, develop plans to manage the flow of traffic and examine ground and drainage conditions.
The surveys will take place from spring through to the autumn.
Greater Manchester Passenger Transport Executive (GMPTE) is overseeing the multi-million-pound expansion of the Metrolink network to Oldham and Rochdale, Droylsden in Tameside, Chorlton in South Manchester, and Media City:UK at Salford Quays.
Michael Renshaw, GMPTE's Interim Service Delivery Director, said: "We need to have up-to-date information about the new Metrolink routes so that we know what to expect when work starts on building them."
Most of the surveys will take place between 0800 BST and 1800 BST although some will involve dawn and dusk observations of bats and other protected species.