The contract comprises the delivery of 74km of electrified railway as part of a wider £160m Scottish government investment in the line between Scotland’s largest cities.
Electric services will begin in 2019 following the completion of the work on the Edinburgh - Shotts - Glasgow Central line.
“This work contributes to the transformation of services across the central belt as part of the wider package of investment to enhance rail travel between the country’s two biggest cities, meaning passengers will see shorter journey times, increased capacity and better reliability,” says Scottish transport minister, Mr Humza Yousaf.
The project is part of the Scottish government’s overall £5bn investment in rail and will be the fourth line linking Edinburgh and Glasgow to be electrified. Work is well advanced on the route via Falkirk.