sentences:  The trains on Line 1 were moved to Line 4 between 2011 and 2013 to replace the older MP 59s, though only 48 trains are used for revenue service.The remaining four trains are stored either at Montrouge or Saint Ouen as operational spares.In 1988, RATP possessed a large number of outdated Sprague-Thomson trains, many of which were rapidly approaching 60 and 70 years old.