Morgan Sindall will construct a new £25m station at Haymarket in Edinburgh to create a fully accessible station as well as an integrated train, tram, bus and taxi transport hub.
BamNuttall will reconstruct or remove a number of structures around the central belt in a £27m project.
Carillion will deliver a range of track alterations, also in the central belt, in a deal worth £3m.
The contracts, all of which will see work start in 2012, form part of the £1bn EGIP scheme, which also sees the electrification of 350km of the existing rail network in the central belt.
Work will begin on site in spring 2012 and enhancements will include:
•Refurbishing the existing station building and constructing a new modern concourse to the west of the existing building.
•Constructing a new access bridge, with DDA compliant lifts and escalators, to all platform levels
•Renewing the platform canopies.
BamNuttall’s bridgeworks involve the reconstruction of 18 structures and the removal of two redundant bridges on lines around the central belt. The works will prepare the way for the future electrification of the railway.
Track works are also being delivered on lines around the central belt to facilitate future electrification works.
Network Rail route managing director for Scotland David Simpson said: “The track and bridgeworks contracts we have awarded mean that preparations are well under way to deliver the electrification of rail lines in the central belt – which will cut journey times and increase capacity on key routes into Scotland’s two biggest cities.”
Transport minister Keith Brown added: “This £50m investment for the Haymarket Station Capacity Project and electrification takes us one step closer to revolutionising the rail network in central Scotland.”
Handling four million passengers a year, Haymarket is Scotland fourth busiest station and passenger numbers are expected to reach 10m by 2025.