NEWARK, N.J. — Amtrak said it hopes to have full rail service restored at New York’s Penn Station by Friday, four days after a second derailment in two weeks caused headaches for commuters at the nation’s busiest rail hub.

Amtrak made its announcement on Wednesday after the heads of the two major commuter rail lines that use Penn Station leveled strong criticisms and called for swifter action.

Rail service has been cut back since Monday morning’s derailment took out eight of 21 tracks maintained by Amtrak.

With the Long Island Rail Road and New Jersey Transit still operating on abbreviated schedules Wednesday evening and bearing the brunt of criticism from angry riders, their directors took aim at Amtrak, which owns and operates the tracks, signals and switches in the station complex.

New Jersey Transit customers are “beyond frustrated at the havoc that has been wreaked upon their lives,” NJ Transit Executive Director Steve Santoro said. “It is Amtrak’s responsibility to take immediate action, and all corrective action.”