Commuters on the LIRR's Ronkonkoma Branch Friday morning can, for the first time this week, look forward to a normal trip, according to a spokeswoman for the Metropolitan Transportation Authority.

Sunday's derailment of a freight train on the Ronkonkoma Branch caused service delays as long as 25 minutes in some cases and crews worked round-the-clock this week clearing the car that overturned west of the Wyandanch station and rebuilding a signal box that had been crushed.

"The Ronkonkoma Line is back in business," said Marjorie Anders, an MTA spokeswoman.

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"There will be normal service on all lines," she said of Friday morning's commute.

During Wednesday's evening rush hour on the LIRR, about five trains were briefly delayed by a signal problem in the East River tunnel and Thursday night's commute was normal, according to the LIRR.

The signal box repairs on the Ronkonkoma line were fairly extensive, as it had to be built from scratch, reinstalled and then tested.

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Crews relied on the original 1987 paper plans for the signal case, and workers at the Garden City facility had to string 500 wires and dozens of other components inside the case.

The signal case houses all circuitry for three crossings and governs the railroad's speed control system, which is why the LIRR has been operating at reduced speeds near the site.

With Patricia Kitchen

CORRECTION: An earlier version of this story misstated the day of the derailment on the Ronkonkoma Branch.