Full regular train service at Penn Station will be restored by Friday following the derailment earlier this week, officials vowed Wednesday.

“Amtrak engineering forces are making good progress as they work as safely and quickly as possible to repair damage to one of the most complex interlockings on the Northeast Corridor, a location where two tunnel tracks diverge towards the 21 station tracks,” said Amtrak spokesman Mike Tolbert. “Our crews hope to restore regular service to New York Penn Station by Friday.”

An NJ Transit train had a slow-speed derailment during the morning rush Monday, creating a commuting nightmare for thousands in its wake.

The derailment caused major switch damage and shut down eight of Amtrak’s 21 tracks, forcing delays and limited service on NJ Transit, Amtrak and LIRR lines.

“The damage from the April 3 incident includes multiple switches, signals and the mechanisms that control them, several rails, a rail crossing point, signal wires and other components,” Tolbert said. “This work is ongoing with safety as the first priority as crews operate heavy machinery with energized power lines overhead and trains moving by at reduced speeds on adjacent tracks.”

Amtrak’s announcement came hours after the agency was excoriated by the MTA for a “series of unacceptable infrastructure failures.”