Abstract: A rail finder for railroad bridges is compactly and uniquely designed to minimize false signals and decrease replacement and maintenance costs. A weighted lever mounted on switch-box rotatable shaft that is perpendicularly disposed with respect to the rail, has an offset portion directly engageable by a horizontal plate mounted on the inner surface of a rail on a bridge. The plate holds the lever in a horizontal position in the down position of the bride. When the bridge raises, the weighted lever follows the plate and rotates the switch box shaft to where cams move switchable elements from a set of contacts. The contacts of the set are in circuit with green lights permitting train passage when the cams are out of contact with the switchable elements. The compact arrangements allow a pair of rail finders to be mounted side-by-side within the gauge and thus out of the path of loose or low third-rail shoes of electrically-powered trains.