Track work near Rockville Centre will alter service Saturday and Sunday on several branches of the Long Island Rail Road, the agency said.
The work will affect service on the Babylon, Montauk, Hempstead and Oyster Bay branches and at the St. Albans station.
Depending on the branch, the work means track outages will reduce service, require substitute bus service or adjust schedules, the LIRR said.
Customers should allow for extra travel time and check special branch timetables available at stations and at mta.info/lirr.
Customers also can call 511, the New York State Travel Information line, and say: Long Island Rail Road.