Faster Freight Trains within Existing Systems

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Hans Boysen

Faster Freight Trains within Existing Systems 25 May 2016 The speeds in freight operation can be raised significantly by adapting existing systems. The slower freight trains on the mainlines are presently limited to a highest permissible speed of 70 km/h, but even for these trains speeds in the interval of 100 km/h to 120 km/h can be achieved. The solution is among other things finer brake tables and to use partly already existing through-signalling. The basis is to realize the practical performance that is there in the existing systems. The majority of freight wagons in Europe have running gear of UIC standard types, single axles with double links or bogies (Y25), which run stably up to 120 km/h (marked ) loaded as well as empty. Utilizing existing locomotives and wagons, practical target speeds can be selected as, for example: -

highest permissible speed 120 km/h, to be used as needed normal speed 110 km/h, considering aerodynamic drag, curtain trailers and noise, possibly lower speed in densely built-up areas average speed including any stops for passes approximately 100 km/h in prioritized corridors, which high-priority freight trains already achieve today on certain sections.

The highest permissible speed of the slower freight trains is constrained mainly by the train’s braking performance versus the infrastructure’s signalling system and by the axle load of constituent vehicles versus the load bearing capacity of the track, whereas the achieved average speed of an individual train is constrained by priorities against other trains in the corridor. Examples of present performance of freight trains, typical of the transportation of heavy goods such as paper: train make-up: locomotive+20 wagons, gross mass 90 tons/wagon, braked weight 58 tons/wagon, brake ratio 64 %, brake mode P, train length 484 m. Train maximum permissible speed on various lines with different signalling is, according to: -

Swedish brake table B (applies in many corridors, without through-signalling): 70 km/h Swedish brake table C (Southern Mainline, with through-signalling): 70 km/h (!) German brake table for brake distance 1000 m and gradient 10 ‰: 90 km/h Norwegian brake table IV for brake distance 1500 m and gradient 10 ‰: 140 km/h

The above limits apply at present. The Swedish brake tables differ by larger steps than those of our neighbouring countries. The tables depend on available brake distances and are not interchangeable with each other, but the German and Norwegian examples still show what is possible within existing systems. Permissible speeds in the interval 100 km/h to 120 km/h could be achieved even for the presently slower freight trains with the aid of: -

brake calculation with continuous functions or new brake tables with finer steps new brake tables which take into account the partly already existing through-signalling even for trains with low brake performance, brake percentage less than or equal to 82 %

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investigating actual signalling distances and extending or changing ATC coding at short distant signals, especially at stations continued upgrading of the track structure for axle load 22.5 tons and 25 tons (and heavier on the Ore Line) when track renewal is carried out.

A key is to utilize the inherent properties of the systems, both for infrastructure and for vehicles, investigate what constrains their performance, and better adapt the systems to each other. The examples here of 120 km/h even with low brake ratios show what can be achieved within already existing systems. For this, neither disc brakes, EP brakes nor ETCS signalling is necessary. The suggested margin between the highest permissible speed of 120 km/h and normal speed of 110 km/h could be used to roll through the troughs between two grades or to make up for delays. Higher speeds for freight trains and smaller differences in speed between different train types can result in fewer passes, longer distances between passes, passage of busy line segments during a longer portion of the day, shorter transport and cycle times, and in some relations step effects with fewer train consists in operation for the same transport flow, and in addition capacity can be freed for more train paths on the line, in all potentially very large benefits even within the existing systems. The industry needs to utilize the possibilities that exist to raise speeds, in particular for the slower freight trains, and to reduce the speed differences for a more even traffic flow on the line. This can contribute to increasing the competitiveness of freight transportation and to raising the capacity of the railway system. This is a large and low-hanging fruit, ripe for picking! Hans Boysen, Lic.Eng. Department of Transport Science Royal Institute of Technology (KTH)

Vocabulary ATC brake ratio (%) disc brake EP brake ETCS signalling highest permissible speed through-signalling tread brake UIC

automatic train control a measure of the brake performance of a train consist; the higher the brake ratio, the higher the deceleration brake with friction pads that grasp separate brake discs electropneumatic brake European Train Control System (part of ERTMS) limited by vehicles as well as infrastructure reduced speed beyond the next home signal is indicated in advance in the ATC brake with friction shoes that are pushed against the wheel treads International Union of Railways (Union Internationale des Chemins de Fer)

http://hallbarlogistik.se/2016/05/25/snabbare-godstag-inom-befintliga-system-2/

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