Thousands of rail passengers face disruption over the next 48-hours as workers at National Express East Anglia strike over pay and conditions.
The action will affect trains to Cambridgeshire, Norfolk, Suffolk and Essex and routes into London and Stansted airport.
Andrew Chivers, managing director of National Express East Anglia, has called the unions' demands of a 2.5% pay rise and a four-day working week as, "totally unrealistic in the current economic climate," and condemned the action.
The Unions' have said that they will strike a further three times next month if a satisfactory agreement is not reached.