Bob Crow has picked the wrong fight this time

Here we go again. The unions' sabres are rattling and Londoners are once more facing the prospect of days of gridlock and chaos if the Tube workers go on strike.

The unions are painting a picture of a public sector employer using anti-union tactics such as increasing use of agency staff, reducing staffing levels and putting lives of passengers at risk by cutting corners on safety.

Reading their list of demands suggests they have a case. The unions claim that ticket offices are being closed, that agency staff will be used to staff stations including the one at the new Heathrow Terminal 5, which opens next month, and security guards will replace normal London Underground staff.

Don't be fooled. Bob Crow, the leader of the RMT, and Gerry Doherty of the usually less militant TSSA are trying to pull a fast one, exploiting the forthcoming elections to extract a few minor concessions out of London Underground.

Senior Tube managers are completely exasperated by the threat and have detailed responses to all the accusations by the unions. There are no plans to extend the use of agency staff; ticket offices are being closed because they are no longer used so heavily due to the spread of Oyster cards; and the service to passengers will be improved by having more staff on forecourts. Moreover, there is no threat to jobs: all staff not only have job security but extra workers are being taken on.

"We have so many changes to work through," said one senior manager, "but if we can't negotiate over these minor issues, then if feels like we are falling at the first hurdle." It is a heartfelt but forlorn plea for the unions to behave in an adult way rather than exploiting every difference of opinion as a battle in the class war.

We have been here before. At the time of the last Mayoral election, there were similar calls for industrial action with threats of a strike on election day itself. The action was called off when Transport for London agreed to "talks" - which in fact they had agreed to in the first place.

Transport for London bosses had been expecting the unions to start agitating for industrial action in the runup to the Mayoral election but they have been surprised at how the unions have started playing hardball so quickly - giving Tube bosses just two days in which to acquiesce to a series of nine demands or face action.

In fact, none of the points raised by the unions are new, nor are they major issues in the overall context of industrial relations on the Underground. A three-year pay deal has already been settled and there are no suggestions of redundancies, despite the proposed closures of ticket offices: staff will simply be redeployed to help on the barriers or platforms. TfL in fact expects to increase staffing levels as it tries to operate more trains to cope with the record numbers of users on the system.

The case for industrial action is so thin that it seems almost as if the unions, who have been out of the papers for several months since signing the long-term deal last autumn, are deliberately courting publicity.

They are playing with fire. Ken Livingstone is privately incensed that Bob Crow is much more militant when negotiating against the publicly run Underground than against the privately owned train operators on the national rail network. Livingstone points out that London Underground is by far the biggest publicly owned railway in the country and yet the unions, which argue constantly for renationalisation, ruin their own case by being so militant in negotiations with TfL. And every time the unions threaten a strike, the renationalisation of the national rail network, for which they have campaigned ever since privatisation a decade ago, becomes a more distant prospect.

Consequently, it is quite feasible that a new Mayor - or even a re-elected Livingstone - might decide that the public-sector model for the Underground is unworkable and that the type of franchising used for the North London line and the extended East London line, when completed, might be applied across the Underground system.

Indeed, if there were a strike, the North London line, which is now part of TfL's London Overground, will be running normally because it is operated by a franchisee, MTR Laing - while the Bakerloo line section out to Watford, which was transferred to direct management by London Underground, would be hit by the industrial action. As a TfL senior source put it: "That is hardly a recipe for us trying to keep more in the public sector if we gain control of more national rail lines." Moreover, if Crow is calculating that Livingstone will back down through fear of the consequences of a strike in the run-up to the Mayoral election, he should think again. Livingstone and Crow fell out badly in 2004 when Crow resigned from the board of TfL. Livingstone had hoped that Crow's appointment to the board two years previously would keep him in the tent but the union man stormed off in a huff when the Mayor urged Tube workers to ignore the RMT picket lines in a shortlived dispute.

Crow and the even more militant members of his executive are therefore eager to see the back of Livingstone - even if that means Boris Johnson becoming Mayor. In the topsy-turvy world of the ultra-Left that Crow inhabits, the militants would actually relish that prospect: in the class war they are still fighting, Tory toffs like Johnson make far better enemies than socialists like Livingstone.

Crow could be overplaying his hand. The travelling public might well welcome the sight of Livingstone standing up to the unions, who are going on strike for pretty flimsy reasons while enjoying guarantees of job security that few commuters can dream of. So Bob, before you drag your members out on a ridiculous strike against a pretty benevolent employer, think how the headline "Ken stands up to the militants" will play to the public. And spare us all the agony of yet more headlines about strike threats and disputes.

Christian Wolmar is the author of The Subterranean Railway, a history of the London Underground, published by Atlantic Books.