My impression is that overhead alignment is more critical with pantographs, especially the narrow ones that San Francisco uses. I have lost track of the number of pantographs we have rebuilt at the Western Railway Museum because the pantograph snagged on a wire that wasn't quite high enough or was in the wrong alignment for the particular pantograph. For example, some wire systems are designed for pantographs that are over the trucks, others for pantographs that are in the middle of the car. In the latter case, the wire design has to consider the length of the car...