Amtrak needs to replace concrete ties along 26 miles of track.
NJ Transit says one of four Northeast Corridor tracks will be taken out of service during the repairs. Riders will face schedule changes, slightly longer trips and boarding changes.
Delays are possible, especially at the Princeton Junction, Hamilton and Trenton stations.
NJ Transit says the work will continue through the fall and may extend into next year.
Advisories will be distributed to Northeast Corridor passengers starting Thursday.
