An Amtrack worker was hit by an LIRR train early Friday, but is expected to survive, authorities said.

The 43-year-old man was struck by an eastbound Port Washington-bound train outside of the tunnel, near Skillman Avenue and 27th Street about 3:30 a.m., according to an LIRR spokesman.

It was unclear what caused the accident.

His injuries were not life-threatening, and he was brought to Elmhurst Hospital in stable condition, authorities said.

An FDNY spokesman said the worker was conscious when EMS arrived on the scene, and not trapped by the train.

Eastbound trains ran express from Penn Station to Jamaica in the early morning, but service to New York City was not affected, according to the LIRR spokesman.