Complex sentence: It connects to, but is not considered a part of, the Mexico City Metro, rather, it is operated by the "Servicio de Transportes Electricos", the authority that operates Mexico City's electric trolleybus system and formerly operated the municipal electric tram system.
Split into simpler sentences: It connects to, but is not considered a part of, the Mexico City Metro. Rather, it is operated by the "Servicio de Transportes Electricos" (STE), the authority that operates Mexico City's electric trolleybus system and formerly operated the municipal electric tram system.