Assessment of the stiffness of railway subgrade

Stiffness of the railway subgrade is a significant factor in maintaining good track quality. Lack of consistency in stiffness leads to various problems such as a poor quality of ride and higher maintenance costs. In order to achieve consistent stiffness along railway lines, an accurate and quick assessment of the existing stiffness is necessary before improvement of the subgrade. Currently, UK Railtrack Line Standards specify a repeated triaxial test to measure undrained modulus in the subgrade; or a plate load test can be used as an alternative method. These methods, however, are not always suitable for measuring the subgrade stiffness in terms of output rates, stress level applied and duration of the stress. This paper reviews conventional testing techniques and describes a novel cyclic penetration test, which is being developed using the California Bearing Ratio (CBR) test mould. The test reproduces conditions similar to those of the railway subgrade for assessment of stiffness properties. The paper shows a close relationship between permanent deformation and CBR values and concludes with a criteria for judging the subgrade stiffness. For the covering abstract see ITRD E125214.


  • English

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  • Accession Number: 01011754
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-947644-43-1
  • Files: ITRD
  • Created Date: Dec 19 2005 3:29PM