Freight Trains for Heavy Haul

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Today the term “heavy haul” conjures up visions of exceptionally long and heavy trains carrying iron ore, coal, phosphates, and so on, on dedicated, privately-owned railways.

This is not accepted by a large number of North American Railroads, where it has been the practice for many years to run long and heavy trains of more general merchandise over considerable distances. It must be said, though, that the specialized mineral railways do have their own problems and are of particular interest. Here we shall discuss two of them.

Early railways developed from horse-drawn wagonways for the haulage of coal in the north-east of England and in Wales. The Stockton and Darlington Railway was the world’s first public railway.

Although it carried passengers, it was constructed primarily for the conveyance of coal and coke and, compared to the horse-worked wagonways, in 1825 rated as “heavy haul”. In the first nine months of operation with steam traction it carried almost 43,000 tons of coal and coke with 4400 tons of general merchandise.


In the United States and Canada in particular, it is economical to run very long and heavy trains over very difficult terrain. Some of the largest steam locomotives were developed in the United States for just such trains, and there are few followers of railways who do not know of the Big Boys, those huge 772,000 lb (345 ton) 24 monsters of the Union Pacific Railroad.

They were built by the American Locomotive Company (Alco) from 1941 primarily for the line between Cheyenne, Wyoming over the 2442 m (8013 ft) Sherman Summit, where a pair would haul 90-100 freight cars with an overall efficiency of no more than 8 per cent at the drawbar. They lasted to the end of steam and one is now preserved.

Individual axle loads of 30-35 tons are not unusual on North American railroads, and some even seek to go to 37 tons. There is commercial pressure in the United States to go to the “125 (load) ton car” with an axle load of 35.7 tons. This worries the Chief Engineers, who are well aware that even with 30-35 tons track and bridge repair costs are “rising at an alarming rate”.

Today there are a number of lines that have been constructed solely for the purpose of conveying coal, iron ore, phosphates, and so on from mines to coastal ports. Descriptions follow of two of these lines, in South Africa and Australia, the first now electrified and the second with diesel traction. There are others in the United States and Canada but, apart from local differences, the principles are similar.

The Minnesota-based Missabe Iron Ranger is one of the few heavy-haul railways specifically dealing in iron ore freight in the US. It is a notable feature of the American scene that more general merchandise us transported in trains with 100 vehicles or more.


The iron ore mines at Sishen in Cape Province are operated by ISCOR (Iron and Steel Corporation). Sishen is over 800 km (500 miles) from the coast, where a specially constructed ore terminal for deep-water vessels has been built at Saldanha. Sishen is some 1300 m (4280 ft) above sea level and the two are joined by 864 km (537 miles) of railway. So that parts of the line could be used by trains of the South African Railways, their gauge of 1067 mm (3 ft 6 in) was chosen The line runs northwards for

175 km (108 miles) in the coastal region then over the next 200 km (125 miles) climbs to around 950 m (3125 ft), mainly in semi-desert terrain. The remaining 490 km (304 miles) undulate between 800 and 1300 m (2600 and 4300 ft). There is one tunnel and a few bridges, but in the main the line runs through open country.

The terrain traversed is particularly unfriendly. In the coastal region there is frequently salt-laden spray from the ocean; much of the line runs through semi-desert with wind-driven sand. Many severe electrical storms occur, with particularly bad lightning. None of this is particularly attractive to electric traction engineers.


At first trains of 202 wagons with a gross laden weight of 20,200 tons (19,840 tons) were hauled by five diesel-electric locomotives, but it was planned from the beginning that the line would be electrified. The South African Railways are electrified on the 3000V dc system, but it was clear from the outset that it would not be suitable for the ISCOR operation. ISCOR chose a 50kv (rather than 25kV) single-phase ac system as only six feeder stations would be required as opposed to 21 for a 25kv system. The operator would have had to fund the additional feeder stations and transmission lines in a very sparsely populated area.

ISCOR specified the same gross load of 20,200 tons (19,840 tons). This meant that to provide sufficient traction for starting such heavy trains, three six-axle locomotives weighing some 168 tons (165 tons) with an output around 3780kw (5070hp) would be required. These are large locomotives for a narrow gauge railway. Loaded trains from the mines have to negotiate adverse gradients of 0.4 per cent (1 in 250) along stretches of up to 50 km (31 miles) in length, and it was specified that such gradients must be negotiated at a minimum speed of 34.5 km/h (21.5 mph). Also a train of 20,200 tons (19,840 tons) would have to be started on such a gradient and accelerated to the same speed. Down hill the gradients are steeper and even longer stretches of 1 percent (1 in 100) gradient have to be negotiated with the speed of the train held at around the same figure. To save mechanical wear and tear, electric “rheostatic” braking is provided, the motors acting as generators. The power produced is dissipated in resistances. The journeys are of necessity relatively slow and, because the line traverses substantially desert terrain, with tropical temperatures by day and relative cold at night (+45°C to —8°C), comfort for the crews is important. Air-conditioning is provided in the driving cabs, which are some of the largest in use and contain a number of comforts for the crew. An interesting item is a small “garage” on each locomotive, which houses a motorcycle. This is situated between the two bogies, and the motorcycle is used by one crew member who inspects the train. It is also useful in the case of a defect. One has to remember that each train is some 2.3 to 2.5 km (1.4-1.55 miles) in length!

The South African iron ore train, with a gross load of 20,200 tons (19,840 tons) and a length of up to 2.5 km (1.5 miles), has to negotiate a windy, semi-desert terrain.





Length of haul:

Max train weight:

Locomotives per train:

Speed on 0.4% (1 in 250) gradient:

Iron ore

1067 mm (3 ft 6 in)

846 km (526 miles)

22880 tons (22470 tons)


34.5 km/hr (21.5 mph)




50kV ac 50 hz



Number of motors:

Continuous rating:

Starting tractive effort:

Traction motor rating:

Motor type:

Maximum speed:

Length, over buffer beams:

Width over body:

Height of body from rail:

Distance between bogie pivots:

Bogie wheelbase:


Locomotive builder:

Electrical equipment:

Number of locomotives


168 tons (165 tons)


3780 kW

565 kN (127,160 lb)

670 kW at 1540 volts

Sep. excited, rectified ac

90 km/hr (56 mph)

20120 mm (66 ft)

2900 mm (9 ft 6 in)

3900mm (12 ft 9½ in)

127000 mm (41 ft 8 in)

3940 mm (12 ft 11 in)

GEC Traction, Manchester

Union Carriage & Wagon




The locomotives are an unusual shape, with a driving cab at one end only. The opposite end of the locomotive has a lowered roof section which houses the current collector and much of the high-voltage switchgear. This arises because, without passenger traffic and hence platforms, the overhead wire is carried lower than would otherwise be the case, and no screening is needed for the high- voltage roof equipment. This does not mean that passenger vehicles cannot be used, should the need arise, as long as they are of the same dimensions as the raised body and cab portions of the locomotives.

Hi-tech electrical equipment is used. The high voltage of 50kV led to some careful design of some components, notably the main protection equipment, particularly because the line passes through an area where there are many electrical storms. Current is collected from the overhead line by a single pantograph on each locomotive, and fed to a single transformer with an input of 5685kVA. To obtain the best performance, the locomotive has continuously-variable thyristor control. The transformer also provides all auxiliary supplies. Current from the transformer’s secondary windings is rectified and fed to the six traction motors.

The original study for the electrification of the line was based on moving some 17.5 million tons of ore each year. During the first 18 months of electric operation of the line, some 30 million tons of ore were shifted. Train loads were increased from the original 202 100- ton wagons to 210 wagons of 104 tons. Later tests were made with a train of 22,626 tons (22,221 tons). As a result, trains were increased to 220 wagons of 104 tons. Train lengths have of course also increased from 2.3 km, through 2.4 km to 2.5 km (1.55 miles).

The first order for 25 locomotives was placed by ISCOR. The line has now been taken over by the South African Railways (SAR), and the locomotives have been designated Class 9E. Subsequently six further locomotives were ordered by SAR, and these incorporated a number of changes dictated by SAR specification. The major differences between the two series are in the driving cabs, now in line with SAR standards, and the bogies.

As can be seen the wagons have also undergone some changes and now have a gross weight of 104 tons (228,800 lb). The terminals at each end of the lines have been specially designed to minimize the time taken for loading and unloading. Trains are normally formed with three locomotives in such a way that there is a driving cab at each end of the rake. Braking of such long and heavy trains is always difficult, especially where different parts of the train are on different gradients. This is particularly marked with a loaded train, and drivers have to take great care where the gradient changes from up to down and vice versa. The continuously-variable control of power of the locomotives assists the driver in making a smooth change from power to brake and back again.


The Pilbara district of Western Australia is one of the most remote and inhospitable places in the world, yet it has no fewer than four standard-gauge railways (1435 mm/4 ft 8 1/2 in) built specifically to carry iron ore. These are the Hamersley Railway, the Robe River Rail way, the Goldsworthy Railway and the Mount Newman Railway. Probably the best known is the Hamersley.

Each of Hamersley Railway’s 47 diesel-electric locomotives is equipped with various hi-tech features suited to local conditions. including air conditioning inside the cabs, extended- range dynamic braking and AAR Type F interlocking couplers.


The Hamersley Railway runs from Dampier on Western Australia’s northern coast south across arid country into a mountainous region, rich in iron ore. In 1964 Japan’s apparently insatiable appetite for iron ore resulted in an agreement between the Japanese and Hamersley Iron Property Ltd for the purchase of some 65.5 million tons (64.3 million tons) of ore over 16 years. The last 25 years have seen a large expansion of output from Pilbara to feed the steel industries of Korea and Taiwan. To service this industry there are today some 1150 km of track.

The Hamersley Railway was begun in June 1965 and construction was very rapid, reaching the first objective, Mount Tom Price, 288 km (179 miles) from Dampier in July 1966. Mount Tom Price rises a little over 700 m (2300 ft) above sea level. Today the terminus at Paraburdoo, reached in 1972, is a further 100 km (62 miles) on, at an altitude of about 400 m (1320 ft). Construction of the Mount Newman Railway, the longest of them all at 427 km (265 miles), was completed in even less time and was in operation 18 months after the contract was awarded.

htt-103cont102 Locomotives are scheduled for a visit to the heavy maintenance area after clocking up 30,000 km (18.600 miles). This picture shows one of the latest models, the Alco C-636R Rebuild (left) which features electronic control and monitoring and in-built toad testing.


In recent years it has been recognized that much useful information has been obtained from the mining lines. The Australians have introduced science into the empirical world of high tonnage, while the North Americans are seeking big financial gains through tight control based on dedicated radio data links. The two extremes get together through the International Heavy Haul Association, IHHA, which was incorporated in September 1986. The qualification for membership is that member railways must operate trains of a minimum of 5000 tons with axle loads of over 21 tons, and move in excess of 20 million gross tons per year.

A large iron-ore carrier, berthing at East Intercourse Island, Port of Dampier. soon to accept its mineral cargo from a Hamersley iron train.


A fleet of 47 3600hp diesel-electric locomotives provide the motive power for the Hamersley. Most were built in Australia under license from American or Canadian companies, all but five having General Electric 16-cylinder engines. The remainder have General Motors engines, installed by Clyde Industries, Adelaide. Until 1985, trains consisted of 180 wagons, each weighing about 20 tons and carrying 100 tons of ore — a gross weight of 21,000 tons (20,625 tons) with an overall length of just over 1.7 km (1.1 mile). Experiments were then carried out with trains of 210 wagons weighing 25,000 tons (24,555 tons) with an overall length of 2 km (1.25 miles). These are the world’s heaviest trains running with head-end power, that is with no helper locomotives along the train or at the rear.

Usually three locomotives haul the trains, which of course run back empty to the mines. In this direction they have to negotiate gradients as steep as 2 per cent (1 in 50) and even with three powerful locomotives hauling the 4200-tonne (4125-ton) train the speed falls to less than 20 km/h (12 mph). As mentioned in the first part of this chapter, the handling of these very long and heavy trains requires a great deal of skill, and today drivers are trained on an electronic simulator. Such training reveals the pitfalls that can be met on the road, and which have to be avoided if there are to be no expensive accidents.

HAMERSLEY RAILWAY ( Australia) specs:



Length of haul:

Max train weight:

Locomotives per train:

Speed on 1 in 140 gradient:

Iron ore


383 km (238 miles)

25000 tons (24555 tons)

6 (3 head end — 3 banking)

33—35 km/hr (20—22 mph)



Wheel arrangement:

Diesel-electric locomotives

5 Clyde-GM — 3600 hp

42 Comeng-Alco — 3600 hp



Weight of rails:

Sleepers (Ties):

American standard

68 kg/m (137 lb/yd)



33 hours

Ground Control

The main control center for the operation is at Seven Mile Yard, 11.2 km (7 miles) south of the port of Dampier. There a visual track diagram shows the location of all trains, and the condition of all signals and controlled points (switches). Taped radio telephone communication is maintained with train crews who can alert Control if there is any untoward incident which may affect the running of that or any other train. The whole area is subject to extreme weather conditions, and weather stations keep a constant watch for cyclones, which bring torrential rain with wind speeds up to 210 km/h (130 mph). The Hamersley aims to shut down about 12 hours ahead of any hurricane and when one is expected, train crews are collected and flown home to their bases, everyone remaining indoors until the danger has passed. Before operation can recommence, the line is inspected from the air and the track before trains are allowed to move again. Normally the railway operates every day except Christmas.

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