The invention relates to a roadway flood protection and traffic barrier which provides a smooth upper surface for vehicles, pedestrians, etc. and is thin enough to be mounted to the surface of an existing roadway or parking garage ramp, for example. A hinge mechanism is disclosed which facilitates the provision of a smooth roadway surface as well as a tight seal. A locking strut is provided that keeps the gate panels raised even in case of air pressure loss and which is remotely controllable.