UAC Turbotrain

America’s Failed High Speed Tilting Train – The UAC Turbotrain

In Vehicles, Videos by Paul ShillitoLeave a Comment


Whilst the US doesn’t spring to mind when you think about high-speed rail, in the late 1960’s it was the first place along with Canada to have a advanced commercial high-speed tilting train service  Capable of 170 mph or 274km/h. It was powered by multiple gas turbine engines, built like an aircraft by an aircraft company ahead of the French TVG and the British Advanced Passenger Train.

But being first doesn’t always mean that it’s the best and it suffered numerous problems that were not always down the trains themselves and it was rather ignominiously withdrawn from the US after just 8 years. This is the story of the UAC TurboTrain.

In the 1960s, the increase in air traffic was causing a problem for the once dominant railways, it was becoming easier to fly long distances by air and much faster than any train could match.

However, on the shorter routes of a few hundred km between major population centres, trains could compete on a more level playing field, stations were usually in the centre of the populated areas, and the trains were quicker and easier to get on and off compared to aircraft at out of town airports.

The problem the railways had was the trains themselves were not very fast and they were limited by the tracks which often dated to the beginning of the 20th century.

In the UK, studies into the increase in passengers due to the introduction of the Deltic engines on the east coast mainline concluded that for every 1 mph increase in speed there was a 1% increase in passengers.

Normally if you wanted to go faster, the curved sections can start to be an issue and limit the speed. In some circumstances, the track itself would be canted or banked but this was expensive to build and maintain. It also wasn’t suitable for some heavy freight trains so it was found that the maximum amount of cant for mixed traffic was about 6.5 degrees.

Passengers trains travelling around flat curves fast was less of a problem, so long as they weren’t travelling too fast that they might come off the tracks it was more to do with passenger comfort. Going fast around a flat curve generates a centrifugal force which pushes the train and everything inside including the passengers outwards, making it uncomfortable and difficult to walk and any loose items like objects placed on a table would be thrown outwards.

To combat this, a tilting carriage was developed. Now whilst Talgo of Spain is normally thought of as the leaders and inventors of the tilting trains in the 1950s, the first tilting railcar was the American Pendulum car built by the Pacific Railway Equipment Company in 1937. This was heavily influenced by aviation engineering with the chief designer coming from Cal Tech and two other engineers from Northrop Aircraft.

The carriage was placed below the roll centre on a special tilting mechanism so that when it entered a curve the whole carriage swung outwards like a pendulum, giving the passengers inside the feeling that it was still on the flat and without the diner plates and glasses flying off the tables.

The result was that it ran smoother and could negotiate corners 20% faster. Three were built a used on different railways but with the start of the second world war, development was halted and their use beyond that was not followed up.

However, there are issues with this pendulum method as there is a delay between the onset of the curve and reaching the proper tilt angle naturally. The carriage tilt angle would overshoot and oscillate as the lateral peak force is reached before settling down. On slow-moving, sharper turns such as negotiating multiple points and changing tracks the swaying from side to side could be quite disconcerting.

Roll on to the 1950s and the Chesapeake and Ohio Railway carried out studies into a tilting train using a second-generation Talgo suspension system which attempted to iron out the previous tilting issues.

These used a single axle bogie between the railcars and the cars themselves sat lower than normal suspended from an A-frame centred on the bogie with a pivot near the top so they could swing outwards.

The linked car meant that they couldn’t be separated easily like normal railcars so the train would be made up of 3, 5 or 7 cars plus a diesel power car at each end with one pulling and the other pushing, this also removed the need to turn a train around.

The power cars had two diesel engines, one on either side with a passageway in between and a control pod above where the crew operated the train from.

At the end of the power car, there were doors behind an opening nose section. This allowed trains to be coupled together to make one long complete train so passengers could walk from one end to the other.

The development of the train went on until the 1960s which coincided with the High-Speed Ground Transportation Act of 1965 and the Department of Transportation looking at including high-speed rail services.

Seeing an opportunity to get into a new high-speed rail business, the United Aircraft Corporation or UAC  bought the patents to the Chesapeake and Ohio Railway concept train to take part in the Northeast Corridor Demonstration Project which was sponsored by the Dept. of Transport.

Two trains called Turbotrains, DOT1 and DOT2 were built by the Pullman Works in Chicago before being sent to UAC for study and testing by their engineers.

The biggest change UAC had done to the design was to replace the diesel engines in the power cars with gas turbines to decrease the weight and this is where the new Turbotrain name came from.

Being aircraft manufacturers they used a turboprop gas turbine engine, the ST6, a modified version of the Pratt & Whitney PT6. This was derated from its normal 500 hp to around 300hp but were smaller and lighter than the diesel’s weighing only 160kg each. The ST6 also used what’s known as a free turbine which acted as a torque coupler and removed the need for another gearbox.

Each power car had three gas turbine engines linked by a mixing gearbox to drive the wheels whilst a fourth ran an alternator for the train’s electrical power. It also had electric traction motors so in New York it could deploy a third rail pickup and run as an electric train in tunnels and Grand Central station.

In keeping with the aeronautical theme, the whole train was built from aluminium in a similar way to that of an aircraft making it half the weight of a traditional diesel powered train, yet with higher strength.

This meant that it required less power to accelerate and maintain its speed and in tests on the mainline between Trenton and New Brunswick, New Jersey in December 1967 one of the prototypes reached a top speed of 170 mph, 274km/h, a record for a gas turbine-powered train that still stands today.

In tests on the Boston to New York route with four stops the Turbotrain cut an hour off the existing time.

To match the speed, the interior was styled like the first-class section of an airliner with reclining seats and fold-down tables.

In Canada where they were also trailing the turbotrain, they were built by the Montreal Locomotive Works. The PR office of Canadian National Railways wanted to emphasise this as a new start for the railways, so they dropped the word “Train” from Turbotrain and called it the “Turbo” in their advertising material.

When the press were allowed on the Canadian trains for the first time they were less enthusiastic. Whilst the tilting train worked well on higher speed curves, on sharper low-speed curves like those into and out of stations the ride was said to less composed and seemed the go around curves in a series of jerks rather than a smooth motion. They also said rail noise was louder than on standard rolling stock.

Canadian National Railways ordered five, 7 car trains with plans to run 2 of them coupled together to carry a total of 644 passengers.

However, on the Canadian debut run from Toronto to Montreal which included a lot of press, the train struck a meat truck as it was crossing one of the nearly 240 highway crossings and nearly 700 agricultural and private crossing along the 330 mile, 534km route.

Although the meat truck was cut in half, the train was relatively undamaged apart from the nose doors and some panel damage which was replaced the next day. This had proven the strength of the aluminium design but had shown up a problem that would eventually add to its downfall.

This was that the high-speed “Turbo” was running on normal tracks which had many hazards like crossings and carried other slower-moving freight trains and other standard passenger trains.

In both France and Japan when they opened their high-speed train networks, the TGV and Shinkansen, they ran on dedicated high-speed tracks with no other traffic and crossings going either over or under the lines.

Although the Turbotrains used proven aircraft engines and technology, their use in a train was new and proved to be problematic. Issues with the brakes in winter, the suspension system, gearbox and what UAC called other minor problems meant that in 1971 the Canadian trains when back to UAC to be sorted out

In 1973 Canadian National sold two, 4 car sets to Amtrack who had taken over the US operations but an accident on a test run wrote off three cars of one of the sets when it was sideswiped by a freight train and the power car sale was cancelled when a sister unit caught fire and was burned out in 1975.

In 1974 after a substantial modification program the Turbo was reintroduced, though on both the US and Canadian services the touted 120 mph, 193 km/h speeds never materialised with the US versions limited to 100 mph or 160km/h and the Canadian one averaging 85 mph, 136 km/h. This was still faster than any other service by up to an hour but due to the track limitations, it fell well short of what was expected, certainly when compared to other countries high-speed trains networks.

Amtrak removed their Turbotrains in 1976 and tried to sell them to Canadian National but due to their poor mechanical condition the sale fell through and they stood idle until were eventually scrapped.

The Canadian service was taken over by VIA rail 1978 and in 1979 one of the power cars on the last three trainsets caught fire after an oil leak and while no one was hurt, a rapid disembarkation was required and the power car and two coaches were burned out.

Even though the Turbo had a rocky start and a reputation for unreliability, after its reintroduction the service was performing well and achieving over 97% availability up until it was withdrawn in 1982.

As they say, a chain is only a strong as its weakest link and in the case of the Turbotrains the track infrastructure was that weak link but other external forces were also at work, the oil price rises in 1973 removed the economic advantage the Turbotrains had of being cheaper to run and other turbine-powered trains like the early TGV and the British APT also ended up ditching their turbines for electric motors.

In the end, the Turbotrains became a failed experiment. Their inability to run at the high speeds promised due to track conditions and their complexity and running costs compared to newer diesel-electric trains did in the end for the Turbotrain what OPEC started in 1973 with the oil price rises, and unlike other attempts at high-speed trains, none of them survived the scrap yard for future generations to visit and learn from.

This just went to prove that even if you have fast trains, if you don’t build the fast dedicated tracks to run them on, then you don’t have a high-speed network.

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Paul Shillito
Creator and presenter of Curious Droid Youtube channel and website

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