Crews begin work on the East Side Access project Monday.
Some peak trains will be canceled, while a number of other train times will change.
Special timetable cards detailing all the changes are available at LIRR stations.
Officials say that from July 22 through August 16, five rush hour trains - three westbound and two eastbound - will be canceled while work is performed in Harold Interlocking in Queens.
Additionally, four peak Hunterspoint Avenue/Long Island City trains will terminate at or originate from Jamaica.
See MTA.info or the LIRR's special East Side Access Work Summer 2013 Service Changes brochure.