Contract will be biggest station upgrade undertaken by Network Rail in current spending period

Six contractors have lined up to bid for the biggest station upgrade undertaken by Network Rail in its current spending period.

The £90m deal is the largest job on the £644m revamp of Reading station, and Network Rail has invited the teams for an interview in the first week of March, from which it will shortlist three.

They include a Costain/Hochtief joint venture, BAM Nuttall, Vinci and Balfour Beatty. Morgan Est and Carillion are also believed to be in the frame.

The station upgrade has superseded the £50m viaduct as the largest construction package on the project because the rail operator bundled the early and main station works into one package.

A Network Rail spokesperson said: “We had to provide a requirement for South Western trains to run 12 carriages by 2011, which meant platform and canopy works had to be done early. But that programme has been pushed to 2014, which means we can roll the early and main works together.”

The main station work at Reading, which is one of the busiest bottlenecks in the country, includes the construction of five new platforms, two new entrances and a new passenger footbridge providing step-free access to platforms.

Meanwhile, tendering for the viaduct – a 2km elevated railway to allow mainline trains to enter and leave the western side of the station without crossing freight tracks – has been delayed by a year, in what Network Rail said was a “major programme slippage”.

A spokesperson added: “We have had to review our original scope, so tendering was set back from September 2009 to the last quarter of 2010.”

A source close to the project said the problem was believed to originate from the gradient of the viaduct being too steep.

Network Rail’s £15bn spending period runs from 2009-14 and so far it has awarded about £10m worth of work at Reading station.