Jettrain

Less energy, more high speed

For a long time, gas turbines were not used for rail applications. But In the United States high speed rail began to be paid attention in some districts. The FRA expressed the next generation high speed rail project to realize high speed operation with less capital cost for infra-structures and electrification. For this purpose high performance, high efficient, emitting less greenhouse gases and non-electric regenerative locomotive was planned. To achieve the performance the same level as an electric locomotive, a gas turbine was the only choice. To regenerate non-electric locomotive, The  FRA requested  the university of Texas at Austin to develop the flywheel battery in 1996. In 1998 the FRA requested Bombardier to develop a turbine powered locomotive. The locomotive produced in 2002 named as "Jettrain".

Design concept

To achieve high speeds on existing non-electrified tracks light weight and high performance were locomotive's target. The locomotive was designed to meet Tier2 Passenger  Equipment Safety Standards established by the FRA.　To get the regenerative capacity, a flywheel battery was planned to add the locomotive. This system would also increase the peak power of the locomotive up to 8000 horse power.

Structure

The next schema illustrates the internal structure of the locomotive. The red part is a gas turbine (5000 horse power, 14800 rpm,525 kg). It occupies small space in the locomotive. The output shaft is coupled to the reduction gear (the reduction  ratio is about 1/4), and rotate 2 three phase A.C. alternators. Total mass of the locomotive is about 90 tons..

To understand the compactness of the gas turbine, let's compare a diesel locomotive with the same output. But there is no locomotive fitted for high speed in the same class. 5000 horse power class diesel locomotives are for freight and very heavy,  200 tons or more. Such a locomotive is not suitable for the high speed service. Recently in Europe, nearly 5000 horse power light weight diesel locomotive has been developed.

The next schema is the internal structure of Voith Maxima 40 CC, the most advanced  hydraulic diesel locomotive. The scale of both schema is almost same. The axle arrangement is C-C and the car body length is somewhat longer than that of Jettrain.

4770 horse power middle speed diesel engine and its auxiliary units occupies large space in the locomotive The red colored portion is the engine itself  and the green colored portion the radiator.　Although the hydraulic transmission is relatively light, a hydraulic converter alone weights 9 tons, far more heavier than Jettrain's  alternator.

Performance

Next schemas show the performance of both locomotive. The above is Maxima 40 CC, below is Jettrain. The vertical axis represents the tractive effort, the unit is KN.
There are large differences in the reduction ratio and adhesion weight between both locomotives but their features can be understood well by comparing schemas.

Maxima 40 CC has three hydraulic converters,  for low speed, middle speed and high speed. This system is as same as that of DD51 and maintains high efficiency in the wide range of speed and has no output discontinuity. But there have been little efficiency advancement of hydraulic converters and this system has no lock-up mechanism. So that the efficiency is inferior to that of the recent electric drive system. Its output at wheel is 15 % lesser than that of JetTrain in spite of a few percent difference between both locomotive's engine output. Yellow curves represent the tractive effort restriction caused by the heat  problem of the torque converter at low speeds according to the environmental temperature

The basic consist of  JetTrain is planned as 7 passenger cars with 2 locomotives at both end. The next table is the comparison between JetTrain and Maglev Transrapid.

In this table, the performance of JetTrain is  hauling 4 passenger cars with single locomotive. Of course Maglev shows the great superiority of the non-adhesive traction system. But for Japanese familiar with the high acceleration performance of Shinkansen, the performance of JetTrain is somewhat unsatisfactory. 5 cars formation has 5000 horse power and 1000 horse power per each car is similar to Shinkansen series 0 EMUs. The performance is similar to each other. But series 0 EMUs were developed over 50 years ago and we would like to expect the more performance although JetTrain is "not electrified". Other middle speed trains in Europe such as InterCity 125 or other middle speed DMUs take more than 6 minutes to achieve 200 km/h and exceeding 200 km/h is still highly challenging. If compared with these trains, JetTrain has obviously good performance.

In the United States, anything heavy, thick, long and large is favored and passenger cars usually weigh about 60 tons. This is quite different from Japan and Europe, where anything light, thin, short and small is favoured.
For example, in the case of locomotive hauled high speed train such as InterCity 125,  a passenger car weigh only 35 tons. If the train is consisted of 2 JetTrain turbine locomotives and 7 passenger cars weighing 35 tons, it will take only 150 seconds to achieve the speed of 200 km/h. This is nearly the same performance as series 700 EMUs. 
However, recent EMUs have far more performance. Series 500 and series N700 Shinkansen EMUs can achieve this speed only in 80 seconds. Recent Shinkansen EMUs have extraordinary acceleration performance in the world that uses the adhesion traction. 

Promotion

The next map shows high speed rail plans over the United States. Many of them are non-electrified high speed plans.

Bombardier actively promoted JetTrain in these areas
The next is the prognostic image planned for Canada.

This is the promotion video of JetTrain（QuickTime player is required)

Wreck of the plan

The strongest candidate for JetTrain was Florida high speed rail plan. In 2003 the high speed rail project was decided to start and JetTrain was adopted  But the inhabitant poll denied this project itself in 2004. There were active lobbing by opposing forces against high speed rail such as aviation related or road and automobile related industries.

The American society is ruled by the law of the jungle based on the market fundamentalism and there are strong antipathies to use public funds on such a project. Financial difficulties of the government are also the important reason. At last, Bombardier stopped the promotion and closed web sites jettrain.us andjettrain.ca.

JetTrain in Britain?

In UK, there has not been, what we call, modern high speed rail for many years. While the mainstream of the high speed rail operates at the speed of 300 km/h,  InterCity 125 remains 200 km/h operation. Some other new type of DMUs have put into service but the maximum operating speed has not increased. To break through the diesel limitation, As British Rail has long distance non-electrified lines, it has been in want of the non-electric high speed train for a long time.
In this century, Bombardier proposed 3200 horse power turbine powered high speed train, named "Jetrain" and  downgraded version of JetTrain for UK but there was no further advancement in this field.

In 2006, UK government's chief transport adviser, Sir Rod Eddington favored the plans for a new high speed rail link and JetTrain technology. But the high cost rise of fossil fuels disturbed the plan.

The JetTrain technology will be attractive when coupled with light weight passenger cars used in UK InterCity 125. As is already mentioned on other page, it can achieve the performance almost as same as that of Japanese seires 700 Shinkansen EMUs,. This is the former generation of Shinkansen EMUs but it is significant that the equivalent performance can be achieved on non-electrified lines.

Shale gas revolution

The shale gas revolution may change the high speed rail environment. Reduced fuel costs may give turbines superiority over an electrified rail where the traffic is  relatively small volume. The environmentally friendly natural gas burning is suitable for gas turbines Turbine powered trains may become active again just like 1960s.

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