"The current layout of Lehigh Valley International Airport requires outbound passengers to travel through an underground tunnel to pass through the security checkpoint, then go up two escalators to arrive at the departure building. Arriving passengers travel the opposite direction through the same tunnel. 

Construction of a bridge between the main terminal and departure building means departing passengers will go up one escalator and cross the bridge to get to the departure building, while arriving passengers will continue to exit through the underground tunnel." 

- thebrownandwhite.com