Heaviest trains

The heaviest trains in the world are freight trains hauling bulk commodities such as coal and iron ore.

The weight of trains generally do not include the weight of the operating locomotives; this is not considered dead weight so is not included. If for example a train had two locomotives operating and was simply hauling a third off line, this third locomotive would be included in the payload weight.

If the track and its alignment are strong, gauge is not so important. Among railways with over 20,000 t (19,684 long tons; 22,046 short tons), the Sishen–Saldanha railway line use 1,067 mm (3 ft 6 in), while the others use 1,435 mm (4 ft 8 ¹⁄₂ in) standard gauge.

Most Pilbara region Railways operate on pre-stressed 68 kg/m (137 lb/yd) rail, meaning that each metre of track weighs 68 kg or each yard of track weighs 137 pounds. This gives the track the strength to carry such heavy loads.

The highest permitted weight per axle is:

Compare:

The track bed and the strength of the rails themselves limit the axle load.

line load is the weight per metre or foot of train length. The strength of bridges is what mainly limits this. Examples:

Curves must not be too sharp, otherwise wagons may be pulled off the track and derailed, especially with general freight trains where light and heavy wagons are intermixed. The meaning of "too sharp" depends as much on experience as on a specific formula.

The couplers must be strong enough in heavy trains. Janney couplers are used for the heaviest trains. The SA3 couplers handle trains of 6,000–8,000 tonnes (5,910–7,870 long tons; 6,610–8,820 short tons), as Russian trains limited by loop lengths, etc.; maximum load of SA3 couplers have not been tested. The standard buffers and chain couplers used in Europe can only handle 3,000–4,000 tonnes (2,950–3,940 long tons; 3,310–4,410 short tons) train weight, but trials are made to push this limit to 5,400 tonnes (5,310 long tons; 5,950 short tons).

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Wikipedia