BAM Rail McCann JV has been award a £16m contract from Translink to upgrade the railway line between Londonderry and Coleraine.
The company will be responsible for the construction of the track relay between Coleraine and Castlerock and Eglinton and Derry.
The project began yesterday (Monday) and runs until April 2013.
Work also includes the installation of new drainage, new ducting for signalling cables, the overhaul of the Bann Bridge and reconstruction of Pottagh Bridge.
The contract is a major part of the Translink’s Coleraine to Derry track renewals projects, which is being funded by a £50m investment for the UK Department for Regional Development (DRD).