Trains running just a few minutes late into Waverley station can cause widespread disruption. Picture: Neil Hanna

Trains on the main Edinburgh-Glasgow route could be diverted if required at Winchburgh in West Lothian onto a line via Dalmeny and the Fife line to rejoin the route at Saughton, west of Haymarket in Edinburgh.

The project, estimated by Network Rail to cost £150-250 million, would involve new junctions at Winchburgh and Dalmeny.

The work could effectively reinstate a part of the Edinburgh-Glasgow main line electrification project which was shelved in 2012 to save money.

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One of the three junction options. Picture: Transport Scotland

Transport secretary Michael Matheson today announced £15m to develop the plans.

Three options for the new junctions will be explored.

Mr Matheson said the western approach to Edinburgh Waverley station was such a critical and busy part of the Scottish network that trains running even a few minutes late could cause significant delays to others and knock-on disruption across other routes.

The scheme could comprise a shelved part of the Edinburgh-Glasgow main line electrification scheme. Picture: Network Rail

He said: “With Edinburgh being a key economic driver for the country, a reliable train service is essential for commuter and business travel.

'Greater resilience'

“It provides confidence to businesses and commuters alike that rail is the best option for their journey and thus enables the continued growth and prosperity of the city.

“One of the key aims of the Edinburgh Waverley Western Approaches project is to provide additional capacity to reduce these constraints, improve performance and give greater resilience across the railway.”