London 2012 Olympics: Tube workers ballot for strike after rejecting £500 Olympic bonus When RMT secured the Docklands Light Railway deal, which will see workers receiving a £100 a shift bonus for turning up for work, Bob Crow the union's general secretary, said it had "raised the bar" for other deals. The union's hard line over the Olympics deal is set to spill over into the London mayoral election with Boris Johnson, the Tory incumbent, promising to introduce driverless trains to curb the power of RMT. Rejecting the London Underground offer, Mr Crow said today: "RMT reiterates our stance that all grades of transport employees are entitled to a decent financial reward for their efforts transporting huge numbers of passengers during the Olympics and are entitled to take leave during the summer. Working conditions and important agreements should not and need not be attacked in order to facilitate Olympic running. Reacting to RMT's move, Howard Collins, London Underground's Chief Operating officer, said: We have been in discussion with the unions for many months about working patterns during the Olympics and have put forward our proposals about how to fairly reward staff. We have scheduled further discussions with the unions on the issue today and have also agreed to continue talks at ACAS later on this week should an agreement not be reached at these discussions. The news comes as giant Olympic rings were launched on to the River Thames to mark 150 days until the start of the London Games. The rings, standing at 11 metres (36ft) high and 25 metres (82ft) wide, were transported on a barge in the centre of the city and are to pass landmarks including Tower Bridge and Canary Wharf throughout the day. Coloured on one side and with white LED lights on the other, the rings were originally intended to start their journey at Battersea Bridge but instead were unveiled at London Bridge, meaning that they missed going past the Houses of Parliament as planned. A spokesman for the mayor of London's office said this was because of "various issues relating to tidal flows and the height of the river." The Rings on the River are to go into storage until the start of the Olympics, when they will again appear on the Thames.