Disclosed is a modular bridge, typically for temporary use to enable persons to pass between upper floors of adjacent buildings during fire fighting or disaster relief operations, which can be rapidly assembled and deployed within a confined space and entirely from the "home" side of the gap to be crossed. It comprises a plurality of man-portable box section bridge modules adapted to be connected together end to end and projected in cantilever fashion from one side of the gap to the other. The assembly of modules is supported in and guided through a launch frame, with modules being added to the rear of the assembly and pushed through the frame until the gap is spanned. Removable lever arms of the frame are used to counterbalance the weight of the projected bridge modules during the course of deployment.