Seven companies will compete for the right to construct the St James Spur, one of four new bridges earmarked for the new route.

The viaduct, which will span the St James Playing Fields in Paisley before crossing the motorway, is the biggest piece of infrastructure for the long-awaited £210m link.

Around one mile of extra track will be laid to allow the link to merge into the main Glasgow-to-Paisley line.

A new airport station will be built south of the multi-storey car park and will feature a moving walkway connection to the air hub.

Both the new station's platforms will be built 30ft from ground level and will be located close to the airport's Terminal 1.

Transport Minister Stewart Stevenson announced that BMV, a joint venture between Balfour Beatty, Morgan and Vinci, have bid for the lucrative viaduct contract, along with Carillion, Morrison Construction and Roadbridge/Sisk.