Techniques for secure debugging and monitoring are presented. In accordance with the invention, the measuring head comprises insulating means, placed on the body on both sides of the electrode along the length of the hole in order to form a measuring area, electrically insulated from other parts of the hole, around the electrode placed in the hole. By preference infra red light is emitted at one focal point of an elliptical reflector, and detected at the other focal point. Methods for manufacturing by mechanical or semiconductor methods are also provided. A plurality of pylons support the catenary and track cable systems.