I'm well aware TGVs are often diverted to run on conventional SNCF lines, but can "conventional" trains such as loco hauled IC run on the high speed network? Last year I thought some Bordeaux to Marseille intercity trains were due to call at Montpellier Sud de France but can see none at the moment. The reason for this query is associated with the possible reinstatement of intercity night trains in France. Night time traffic on lignes grand vitesse appears sparse and I wondered if there spare capacity there?