US Patent 7463348 Rail vehicle mounted rail measurement system

A rail measurement system (10) for mounting on a rail vehicle (e.g., 12) for travel over a railway (16) having two spaced apart rails (18, 19) includes a first collimated light source (20) mounted on the rail vehicle for providing a first reference marker (22) relative to a first rail of the railway. The system includes a camera (28) mounted on the rail vehicle for recording an image of the reference marker relative to the first rail. The system also includes an image processor (50) coupled to the camera for analyzing the image of the reference marker relative to the first rail to determine a first rail alignment dimension (e.g., 39) with respect to the reference marker.