Last week I was on holiday in France. Driving down from Paris to Orléans on the D2020, I noticed a long raised structure to the east running for several kilometres. It was a few hundred metres from the road so all I could see was a raised platform or aquaduct on stilts. I initially assumed that it was related to the energy industry because the structure passed near a nuclear power station. I thought nothing more about it for a few days and then used Google Maps and Street View to find out that this was an actually the industrial remnants of a high speed transportation experiment called Aérotrain from the 60s and 70s which achieved speeds of over 400 km/h (about 250 mph).
Generically known as a hovertrain, the Aérotrain used a cushion of air to reduce the rolling resistance of the vehicle, in a similar way to maglevs. Aero engines were used from propulsion, initially with propellors, then turbojets and finally turbofans. A prototype using a linear induction motor was also tested.
The futuristic vehicle on the left is the I-80 HV and is shown on the track that I passed between Ruan and Saran. Able to carry 80 passengers, the I-80 HV established the world speed record for overland air cushion vehicles on 5 March 1974 with an average speed of 418 km/h (259 mph) and a top speed of 430 km/h (267 mph).
This was the brainchild of French engineer Jean Bertin who initially proposed the concept and demonstrated a scale prototype in 1963. Subsequently there were four prototypes built for France and one for the USA which ran on a test track in Pueblo, Colorado.
It’s totally fascinating and there are some comprehensive information resources online including the Association of Friends of Jean Bertin (in French) and Aerotrain.fr (French and English). There are some videos on-line too which show how amazingly futuristic the Aérotrain must have seemed in the 60s. The one below is nearly 20 minutes long. There’s a couple of videos on YouTube too – search for aerotrain.
For a quick 3 minute fix, French pop group Exsonvaldes released a music track with a video about the Aérotrain. There’s brief sequence of the I-80 HV keeping pace with a light aircraft.
State support for the Aérotrain ceased in 1974 and France pushed forward with the TGV for high speed rail transportation. The key benefit of the TGV was that the trains could run on standard rail tracks in urban areas before switching to dedicated high-speed lines in the countryside. Aérotrain needed a completely new infrastructure and the last flight of Aérotrain took place on 29 December 1977.
For comparison, here’s a BBC top five fastest trains. There’s some learning here for Elon Musk’s Hyperloop system.