Passenger boarding bridge

A passenger boarding bridge comprising:

• a rotunda connected to a terminal building;
• a tunnel unit whose proximal end is connected to the rotunda, the tunnel unit being extendable and retractable, the tunnel unit being rotatable about the rotunda;
• a cab provided at a distal end of the tunnel unit, the cab being configured to be docked with an aircraft;
• a travel device that supports the tunnel unit and includes travel wheels configured to travel forward and backward, the travel device being configured such that a direction of forward travel of the travel wheels and a direction of backward travel of the travel wheels are changeable;
• an operating device that is operated to input an operation command to the travel device;
• and
• a determiner configured to repeatedly perform determination whether or not the current direction of the forward travel of the travel wheels is a direction within a forward-only travel docking enabling range during a period from when the cab starts being moved from a predetermined position until the cab is docked with the aircraft, the cab being moved through an operation of the operating device to cause the travel wheels to travel.