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Ballast after degradation test

Degradation of railway ballast for high-speed rail

What requirements should be set for macadam ballast for high-speed track? In the project, the degradation processes are studied, test methods and the availability of materials is mapped around previously planned routes for high-speed tracks (> 250 km/km) in Sweden. Today's requirements abroad for ballast for high-speed lines are compiled.

Macadam ballast in railway tracks

In a ballasted track, the loads from passing trains are transferred down to the railway embankment via sleepers. Sleepers are embedded in the ballast in the track superstructure at the top of the embankment. The ballast is subjected to high and repeated loads when the track is in operation. This leads to a gradual degradation of the aggregate grains that differs at different locations in the ballast layer.

The degradation processes are complex and depend not only on the loads but also on the basic properties of the chosen rock material, microcracks in the grains, grain shapes and grain size distribution, how the material is laid out and compacted in the track. The design of the substructure has an impact on bed stiffness. Degradation also occurs during track mainenance work, e.g. in conjunction with track alignment. The production methods of aggregates affect the quality of the aggregates and their resistance to degradation.

A literature review is conducted where the degradation mechanisms are studied and research on aggregate degradation is compiled. The relevance of today's requirements and standardized test methods is evaluated.

Availability of materials for high-speed lines

The geological conditions and existing aggregate quarries along the routes are described. Materials from a number of selected quarries are selected and evaluated using the test methods specified in the standard for railway ballast; EN 13450. The materials represent different ballast grades that have a spread in technical properties within today's requirements for railway ballast for conventional tracks that are not intended for high speed.

Summary

Project name

Railway ballast for high-speed rail

Status

Completed

RISE role in project

Projektledare, deltagare

Project start

Duration

1 år, 6 månader

Total budget

1 600 000 kr

Partner

The Geological Survey of Sweden, SGU

Funders

Swedish Transport Administration

Project members

Supports the UN sustainability goals

9. Industry, innovation and infrastructure
11. Sustainable cities and communities
Lars Jacobsson

Contact person

Lars Jacobsson

Senior forskare

+46 10 516 56 19

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Björn Schouenborg

Contact person

Björn Schouenborg

Filosofie doktor

+46 70 520 25 51

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