Line T3 will link Châteaucreux, the city's main railway station and terminus of Line T2 with La Terasse mainline station, which is also served by light rail line T1. Two route options, one 3.5km and the other 4.5km, are being considered, and the total budget for the project will be €65-80m.

The line is expected to substantialy reduce journey times between Châteaucreux station and the north of the city and will also serve the Technopole business district.

According to the Metropolitan Council a prefeasibility study was completed at the beginning of this year which confirms the project is economically viable.

Technical studies and initial public consultation will begin in the second half of this year with the aim of completing a public inquiry by the second half of 2016. Construction is expected to begin in the first half of 2017 and Line T3 will open in late 2019.