A £250 million contract to electrify rail lines and extend station platforms has been awarded as part of a project to improve journey times between Scotland's two biggest cities.

Costain and Morgan Sindall are to work with Network Rail on the engineering aspects of the Edinburgh-Glasgow Improvement Programme (EGIP), with piling works to create the foundations needed to erect overhead power lines starting this week to be completed by next summer.

It is hoped the improvements will reduce journey times between Glasgow and Edinburgh by 20% and increase capacity on the trains by 30%.

Earlier this year, it emerged that the cost of EGIP had risen from £650 million to £741.5 million. Funded by the Scottish Government, the project will deliver a rolling programme of electrification across the central belt over the next five years and beyond.

The project will also see route clearance works at Winchburgh Tunnel and platform extensions at Croy, Falkirk High, Polmont and Linlithgow stations.

Edinburgh Haymarket has already been redeveloped as part of the project at a cost of £25 million and Glasgow Queen Street station is to be given a significant makeover, along with the construction of the Edinburgh Gateway Interchange station at Gogar.

Speaking at a training base in South Lanarkshire, Transport Minister Keith Brown said: "This £250 million contract marks a significant milestone in the EGIP project, which will provide 20% quicker journey times, 30% more capacity and a complete overhaul of stations in both cities, with the new-look Haymarket station already completed on time and under budget and the planned transformation of Queen Street station into a 21st-century transport hub.

"The Scottish Government's record levels of investment in our railways is achieving even more than improved train journeys. It's providing jobs and training opportunities such as those in the Babcock Training Facility in Hamilton where we are making this announcement.

"That is, in turn, contributing to Scotland's growth and the sustainability of our engineering sector, as well as a bright future for the young people here setting out on a career path in the rail industry."

Rodger Querns, Network Rail programme director, said: "EGIP is a unique chance to modernise and enhance our railway and transform rail services across the central belt. It is transformational in its scope and scale and will herald a step-change in the nature of our railway infrastructure, its resilience and reliability."