The Government is expected to rubberstamp rail plans this week that unions claim could risk lives and that are "even worse than privatisation by stealth".
Network Rail, the state-backed owner and operator of Britain's rail infrastructure, is finalising the details of a pilot scheme that will see it and Ftse 250 group Stagecoach jointly run a section of the network.
It is hoped that the so-called deep alliance will be in place next month and it is thought the Department for Transport and the Office of Rail Regulation could sign off the proposal in the next few days.
However, railway unions are concerned that this is a very similar set-up to that run under Network Rail's predecessor, Railtrack, which took some blame for the Hatfield and Potters Bar derailments in 2000 and 2002 respectively.
These disasters spelt the end for Railtrack, which collapsed with huge losses in late 2002. It farmed out track maintenance to private sector contractors.
Mick Whelan, the general secretary of Aslef, the train drivers' union, said: "We see this as even worse than privatisation by stealth as it puts the track in the hands of the poacher to do the gamekeeper's job. If you reintroduce the profit motive like this then we have got health and safety concerns."
The deal will see Stagecoach subsidiary South West Trains form a joint management team with Network Rail for the Wessex route operating out of London Waterloo. This team would look after both trains and tracks, but there are fears that the private sector will dominate the alliance: South West Trains managing director Tim Shoveller will lead the combined team.
The alliance will be the only one of its type during the current control period – the five-year planning system that Network Rail uses to sort out its budget and operations – which ends in 2014.
However, under reforms proposed in a report by Sir Roy McNulty last year to improve value for money in the rail industry, more of these alliances are expected to follow in a few years.
Rail industry sources have dismissed many of the unions' concerns, believing that their real focus is that by merging teams, some jobs will ultimately be lost due to duplication of responsibilities. For example, only one team planning the timetable would be necessary rather than two thrashing it out to get the best deal for their employer.
One source argued: "Look, under these proposals both South West Trains and Network Rail retain their existing regulatory frameworks. The only change is that there is a single management team; there is no change to the safety regime. The arguments don't bear scrutiny."
The unions are also concerned about the future of rail freight, as they believe that private companies would push through more passenger trains, where they derive much of their revenue.