More strike action has been threatened ahead of, or even during, the London Olympics, with workers at four different train companies being balloted over possible industrial action.
Members of the Rail, Maritime and Transport (RMT) union at South West Trains (SWT), Greater Anglia and First Great Western will start voting this week in a row over a bonus for working during the Games.
Meanwhile, the Transport Salaried Staffs Association (TSSA) is balloting members on the West Coast line over the suspension of a union rep by Virgin Trains.
The ballot will end on July 18, less than two weeks before the start of the Games, and the TSSA warned that action could be held during the Olympics.
The RMT ballots will end on July 19.
SWT insists it has already struck a pay deal with the RMT covering the Games period and has made it clear it will not offer any more money.
But RMT General Secretary Bob Crow said it was "a scandal" that SW Trains, Greater Anglia and First Great Western had "decided to try and force their staff to work longer and harder for little or nothing in return."