Schedules on some New Jersey Transit rail lines may be subject to change while the agency completes installation of its Positive Train Control safety system.

The system upgrade means that some weekday trains may be discontinued or start or end at different places.

NJ Transit says that riders who use the Northeast Corridor, Coast Line, Morris and Essex and Pascack Valley lines will see the most impact. Riders are urged to check the NJ Transit website or NJ Transit rider app for changes.

The service adjustments are expected to last until early next year.

The safety system is designed to control and monitor a train’s speed to potentially prevent deadly crashes and derailments.