2011) Strasbourg (July 1958 to 2009) Thionville (1993 to 2010) La Villette (June 1962 to 2003) Experimental locomotives BB 16540 was rebuilt into BB 20004 from 1959 to 1969, as a prototype "small dual-current" locomotive (more powerful under alternating current than under direct current); it then worked trains on the “Étoile de Savoie” lines which radiate around La Roche-sur-Foron. It was returned to the class at the end of its test period and regained its initial number. BB 16515 , BB 16549 (withdrawn in November 2007), BB 16550, BB 16575 (withdrawn in December 2006) and BB 16592 (withdrawn in December 2009) were marshalled between two stainless steel RRR push-pull fitted sets. The disadvantage of their discomfort was thus circumvented, the driver's cabs not being used in normal service. These “dromedary trains”, so called because the loco formed the camel's hump in the middle of the train, were put into service on the TER Picardie line between Paris and Beauvais. The locomotives were repainted with a service-specific livery. Since 2007 the operation of dromedary trains was abandoned with the arrival of more modern TER multiple-unit trains. The locomotives and stainless steel trains then resumed service in classic configuration on other TER Picardie routes. 16655 was delivered directly in 1961 as a CC 10002 prototype intended for the development of a lightweight single-engine type C bogie (three driving axles driven by the single motor of the bogie by a gear train), used on a class of Finnish diesel-electric locomotives then later on the CC 40100s, CC 72000s, CC 6500s and CC 21000s of the SNCF. It was rebuilt as a class BB 16500 under its initial number in 1970. Scheduled for automatic coupling tests, BB 16700 was equipped for this purpose with a reinforced and elongated frame and end caps, which it kept until it was scrapped in 2007. Between 1988 and 1990, BBs 16780 to 16784 were equipped with a multiplexing device allowing ore trains to be hauled by three locomotives distributed along the convoy and controlled by the leading locomotive thanks to a cable which transmitted the information. The principle was subsequently modified (1990-1993), with the information being transmitted from one locomotive to another by radio. The experiment was renewed in 1998-1999 with BB 16781 and 16782 with the aim of running very long, , and very heavy, , trains. The experiment did not lead to concrete achievements and the