The unrest presents Mr Macron's biggest challenge since his election last May.
Workers with state-owned SNCF enjoy generous conditions, including automatic annual pay rises, early retirement, 28 days of paid annual leave and protection from dismissal. Their close relatives are also entitled to free rail tickets.
The Macron government wants to phase out the special SNCF contracts, proposing to put new hires on conditions like those that apply elsewhere in industry.
The action will spread over three months, affecting two days in every five.