Police said the accident happened on Route 15 South near exit 63 at around 9:30 a.m., while the worker was placing a wheel chock against his left tires in the closed lane. The worker was hit by a car and was taken to the hospital with serious but non life-threatening injuries.
The southbound side was closed, but the left lane was soon reopened and all lanes were open by noon.
The DOT said the 53-year-old worker has been with the department for 14 years.
"I can't stress how close we have come today to losing another employee," said DOT spokesperson Kevin Nursick.
Nursick said crews put up all the proper signage, but must then rely on the public to drive safely.
"In a work zone, we're looking for folks to be hyper aware of their surroundings, reduce their speeds," said Nursick.
"The law requires that operators slow their speed and move over where possible in order to promote everyone's safety, including their own," said State Police Col. Alaric Fox.
Nursick said Wednesday's incident was entirely preventable, and that the worker now faces a long road to recovery."These are not scrapes and bruises," said Nursick. "They are major, serious, severe injuries."