2026-04-22
In 1965, a strange vehicle screamed across the flat plains of Orléans, France at 422 km/h (262 mph). It floated on a cushion of air, guided by a concrete monorail, powered by a rear-mounted aircraft propeller. This was Jean Bertin's Aérotrain, and it was the fastest ground transportation on Earth at the time. It should have changed everything. Instead, it was quietly killed by politics.
Jean Bertin, an engineer from SNECMA (the French jet engine manufacturer), founded Bertin & Cie in 1956 and began developing air-cushion vehicles. His insight was elegant: instead of fighting friction with wheels on rails, eliminate contact entirely using pressurized air bearings against a simple concrete guideway. The vehicle would hover roughly 5mm above a T-shaped track, steered passively by the guideway geometry. No complex magnetic levitation systems, no superconducting coils, no cryogenics — just compressed air and aerodynamics.
Between 1965 and 1974, Bertin built and tested multiple prototypes:
The technology worked. The French government signed contracts. A Paris–Orléans commercial line was planned. Then in 1974, everything collapsed. President Georges Pompidou, Bertin's political champion, died in office. His successor, Valéry Giscard d'Estaing, favored the conventional TGV project pushed by SNCF, the national railway monopoly. SNCF had an existential interest in keeping trains on steel rails — their entire empire of stations, workshops, and labor unions depended on it. The Aérotrain contract was canceled. Bertin died the following year in 1975, aged 57. The 18km test track outside Orléans sat abandoned for decades, its concrete guideway slowly crumbling — a monument to institutional inertia.
The standard criticism was noise (those aircraft engines were loud) and energy inefficiency at lower speeds. But these were engineering problems specific to 1970s propulsion, not fundamental flaws of the air-cushion concept. The guideway itself was the breakthrough: a simple, cheap concrete beam that cost a fraction of conventional rail infrastructure. No ballast, no precision-aligned steel rails, no electrification masts — just poured concrete.
Modern technology eliminates every historical objection. Electric ducted fans and linear induction motors solve the noise problem entirely. Contemporary composite air bearings are vastly more efficient than 1960s designs. CNC-manufactured guideway segments could achieve millimeter tolerances at scale. And crucially, the infrastructure cost argument has only gotten stronger: high-speed rail construction now costs $25–100 million per kilometer in Europe, while a concrete monorail guideway could be built for a fraction of that using automated slip-forming techniques borrowed from highway construction.
The Aérotrain concept occupies a fascinating middle ground between conventional rail and Hyperloop. It doesn't require a vacuum tube. It doesn't require superconducting magnets. It requires concrete, air compressors, and electric motors — technologies we mass-produce today. For medium-distance routes (100–500 km) in developing nations that lack existing rail infrastructure, the air-cushion guideway concept offers high-speed transport without the ruinous cost of conventional HSR construction.
Jean Bertin's 18km test track was finally demolished in 2017. But the physics hasn't changed. Air bearings still work.