Frustrated Long Island Rail Road riders headed back to work Wednesday after problems caused major cancellations and delays Tuesday night.

The LIRR is operating on or close to schedule with scattered residual delays after thousands of angry Long Islanders were stalled by delays and cancellations at Penn Station.

Amtrak says that the service disruption was due to a problem with a power line in the East River tunnel.

The issue is the latest in a series of slowdowns this month, including two train derailments leading to days of delays.

Amtrak owns and runs the tracks at Penn Station and has been blasted by commuters and officials for poor performance.

The LIRR Board says it may take legal action to force Amtrak to improve maintenance and repairs.

Meanwhile, Amtrak says it is announcing a new plan to review infrastructure at Penn Station. The work could result in some delays and cancellations.