Levitating Ghost Trains of Pueblo

Sitting quietly in an old industrial area of Pueblo, Colorado, on West D Street, one of the "gee-whiz" technologies of the 1970s quietly rusts away.

Here, behind a chain-link fence and some fading signage, rest the prototype Rohr Industries Aerotrain and the Grumman TACRV (Tracked Levitated Research Vehicle).

When I visit Pueblo, I often stop at a coffeehouse about three blocks away, but had it not been for a geocache, I would never have known of their existence. Here is how they came to be there.

Nose of the Rohr Industries Aerotrain. No windshield—the "pilot" watched a video screen. Skirting kept in the compressed air under the train, while the vertical monorail kept it on the track.

Finding them was like driving to the airport by a different route and suddenly discovering a derelict zeppelin hangar. What is that? 

Both "tracked air-cushion vehicles" were designed to float on cushions of compressed air rather than wheels, which potentially offered speeds as high as 300 mph. In the 1970s, both underwent testing at the Transport Technology Center northeast of Pueblo.

The Rohr Aerotrain was a single, streamlined unit with a pilot compartment in front and passenger seating toward the rear. See it and other similar vehicles on this Aerotrain website.

It was a sort of monorail, to be powered by electricity from its track.

Grumman TACRV. You can see the turbine engine air intakes to the rear. The look reminds me of its contemporary, the Space Shuttle.

The Grumman vehicle, in contrast, would run in a sort of concrete trench, pulling hovercraft-style passenger cars, and propelled by gas-turbine engines.

The "pads" on the bottom and sides were where compressed air was forced out to "float" the vehicle.

Grumman TACRV testing at Pueblo (Aerotrain website).

Why did this technology die? The Aerotrain website offers several issues that could not be overcome.

1. Each train would have required a new, expensive sort of track, for which rights of way would have had to be acquired.

2. The Aerotrain's electric induction motors required their own power infrastructure and a lot of electricity.

3. The air compressors, turbines, etc., made these "hovercraft" trains incredibly loud.

4.The Aerotrain's engine built up a static electric charge that had to be grounded before anyone could get on or off.

5. The fans generating the compressed-air cushion also kicked up sand, gravel, etc., like a traveling sandstorm in arid climates. Every part of the train had to be levitated on compressed air, which mean lots of machinery to move air.

For all their City of Tomorrow flavor, they were less practical than improving conventional trains, which are still more energy-efficient on a passenger-mile basis than aircraft or buses.

My next business trip to Chicago will involve steel wheels on steel rails.