Tube strikes cost London £1bn, Conservatives claim 22 August 2013 Last updated at 10:38 Strikes on the London Underground have cost the capital more than £1bn in six years, according to a report. The study by the Greater London Authority Conservatives also calls for Tube strikes to be banned and replaced by a compulsory mediation process. It says there were 30 days of Tube strikes during 2005-11 costing London about £48m each. The Rail Maritime and Transport (RMT) Union has described the GLA Tories as "clowns." The report, called Struck Out: Reforming London Underground's strike laws, says industrial action is going ahead with only small minorities of the workforce voting in favour. Absurd It claims Tube strikes went ahead with an average of just 39% of balloted staff voting for a walkout. It comes as London Overground guards are to stage a 48-hour strike this weekend in a dispute over job cuts. Richard Tracey, GLA Conservative spokesman for transport, said: "It is absurd that tens of thousands of passengers could face delays and disruption on the London Overground this bank holiday weekend because 43% of train guards - a mere 53 workers - have opted for strike action." The party is also calling for strikes to be banned and be replaced with a "binding pendulum arbitration" - in which an independent judge or panel would choose between the competing positions of the relevant trade union and Transport for London. Military junta And a minimum of 50% + 1 of all eligible trade union members would have to vote in favour this sort of mediation to take place, the party said. The report also polled 284 Londoners and found 59% think it is too easy to strike and 48% favoured some form of ban on strikes on the Underground. Mr Tracey added: "For too long, London's Tube unions have been holding the travelling public hostage, demanding ever greater pay deals and calling strikes at the drop of a hat. We need to urgently readdress this imbalance. Bob Crow, general secretary of the RMT, said: "RMT members on the London Overground voted nine to one for strike action on a turnout of 50%. Any politician with a mandate like that would be dancing in the streets. The fact is that the mayor and all the Tory members of the GLA would have to stand down if they applied the same brand of democracy to themselves that these clowns are trying to impose on the unions. This policy on one form of democracy for the political class and another for the working class has the whiff of the military junta about it.