The Pennyslvania Turnpike Commission announced today that it is cooperating with a National Transportation Safety Board field investigation of a fatal, Feb. 21 incident in the southbound Lehigh Tunnel on the Turnpike’s Northeastern Extension (Interstate 476).

The focus of the field investigation is on the conduits and conduit-support system in the tunnel ceiling.

State Police at Pocono said the incident occurred at 6:03 p.m. along Route 476 near mile marker 71.4 inside the Lehigh Tunnel in Washington Township.

A tractor-trailer operated by Howard Sexton III, 70, of Mickleton, was traveling south in the Lehigh Tunnel when the piece broke off from the ceiling, passed through its windshield and hit him.

The vehicle continued to travel south for about 1 mile before final rest on the right shoulder, where Sexton was discovered by Turnpike Safety and State Police at Pocono deceased behind the wheel.

Sexton was pronounced dead by deputy coroner Jason Nicholas at 10:20 p.m. at the scene of the crash.

“We are eager to understand exactly what caused this tragedy so we can work to ensure it doesn’t happen again,” said PA Turnpike CEO Mark P. Compton. “We will continue to cooperate fully with NTSB personnel throughout their investigation.”

NTSB investigators arrived on-site Feb. 23 and will likely complete the inspection by Feb. 28. NTSB officials expect to release a preliminary report in two to four weeks. A final, more detailed report — which would include probable cause and possible recommendations — may take up to a year.

The southbound tube of the Lehigh Tunnel — which originally opened Nov. 22, 1991 — was temporarily closed on the evening of Feb. 21 during incident cleanup and investigation and reopened in the afternoon of Feb. 22 after needed repairs were made to ensure the tunnel was safe for travel.