Commuters just got an unwelcome preview of Penn Station’s impending “Summer of Hell” — after a Thursday night train derailment caused delays that continued through the Friday morning rush.

“I got stuck for about an hour between Newport and Seacaucus yesterday,” huffed Bob McCall, 35, who travels from Keyport, NJ, to his job in the city.

“It’s going to be horrible [come Monday]. People are going to be fed up. I’ve been thinking about buying myself a car.”

By Friday morning, delays were down to 15 minutes, riders said — but they predict that’s nothing compared to what’s in store Monday when Amtrak begins its massive, eight-week reconstruction program, which will take some of tracks out of service around the clock.

“There are always delays, but there will be even more delays than usual,” said Tyler Hoffman, 22.

About 180 people were on the North Jersey Coast Line train from Long Branch when it derailed while pulling into Penn at 9 p.m. Thursday — the third recent derailment at the crippled stop.

Amtrak Chief Operating Officer Scot Naparstek said in a statement Friday that the equipment was re-railed by 2:40 a.m. and service resumed before the morning rush.

Delays Friday morning were “minor” and “congestion-related,” the statement said.

The Port Authority added additional trains Friday morning as a “test run” of its plan to accommodate commuters affected by the Amtrak construction, the agency said in a statement.

The extra trains were also intended to help those affected by Thursday night’s derailment, the statement said.

On Monday, PATH will also accept NJ Transit tickets at Hoboken, 33rd Street and the World Trade Center stations, the statement said.