Truffaut made the suspended metro sequences on a location shoot near Orléans in France. In 1959, engineering film SAFEGE built a 1370 metre track at Châteauneuf sur Loire to conduct tests for a new form of rapid and silent public transport. The project generated much interest from abroad but before the company could sell the technology it would first have to build a working system in France. When Truffaut's team arrived for filming at the test track in March 1966 development for the SAFEGE metro was at its height, and the system seemed likely to be rolled out imminently for commercial operations. At least two proposals were developed for the Parisian suburbs, but the first was rejected due to technical difficulties, and the second abandoned in October 1966 for financial reasons.
A few years later the test track was dismantled and the carriage was sold for scrap. By chance, however, the unit immortalised on film by Fahrenheit 451 escaped the smelter and after providing a home for the iron merchant's son it was used as a chicken hut. Discovered in a field in 1991, the carriage was bought by members of a local association (ARSATI) interested in the history of the Aérotrain - another experimental transport system developed near Orléans in the 1960s and 70s. After restoring the carriage in 1994, ARSATI planned to display the SAFEGE metro in a museum dedicated to innovative transport, but sadly the unique metro was vandalised and the project abandoned.
Truffaut wrote he was determined to use the suspended metro in his film, and remarked that even though it seemed out of date compared to the neighbouring high speed Aérotrain experiments it was still a glimpse into a future that otherwise pretty much resembled contemporary England. Over forty years after the release of Fahrenheit 451, the suspended metro of the film still seems strikingly modern - or at least timeless compared to the brick houses of Montag's street, resembling the London outer-suburban commuter belt of the 1960s, and the sea of rooftop television aerials in the title sequence. The film remains the last resting place of a transport system out of its time.
References to the SAFEGE suspended metro from Le Métro Suspendu website (in French).