Union members working on West Anglia rail services are beginning an industrial dispute in a row over new flexible working proposals.
The West Anglia line runs between Liverpool Street in London to Cambridge. Members of the RMT union have voted to take action short of a strike.
Senior managers say the dispute will not have any impact on services.
Some schools in Milton Keynes are expected to be affected by industrial action by two of the main teaching unions today.
It's the second in a series of strikes which affected other schools in the region earlier in the month.
Members of the National Union of Teachers and NASUWT are protesting against government education and pensions policy as well as pay and working conditions.
Parents are being advised to check school websites to see if they are opening.