General Order 64
Section XIII
Supply Lines Or Signal Lines Crossing Under Railway Structures
133 Conductors.
(a) Where the clearances required in Section IV for open wires can not be observed, the crossing may be made in cable or conduit.
(b) Supply conductors, under this condition, shall be properly insulated for the voltage carried and mechanically protected against injury or accidental contact or shall be run in a grounded metal conduit attached to the bridge structure.
(c) Signal conductors, under this condition, may be placed in suitable conduit or carried as lead covered or rubber insulated cables. If suspension strand is used, the strand where attached to the structure must be so supported as to effectually insulate the bridge structure from any current carried by the cable or its supporting strand.
(d) Trolley Troughs: In the case of trolley contact wires run under steel railways structures, properly insulated trolley troughs shall, where practicable, be insulated to prevent contact between the trolley pole and the structure in case the trolley slips from the contact wire, except where the clearance is sufficient to eliminate the possibility of such accident.