Ruddlesden geotechnical


California Bearing Ratio (CBR) Testing

California Bearing Ratio (CBR) values are used for road pavement design.

Depending on the ground conditions, a number of methods of in-situ testing, which may be supplemented with laboratory testing, can used to obtain CBR values:

Conventional in-situ CBR testing in accordance with BS 1377: Part 9;

Dynamic Cone Penetrometer (DCP) testing; provides a CBR profile with depth and is a relatively rapid test; and

In-situ plate bearing testing, preferred in coarse-grained soils that are unsuitable for conventional CBR or DCP tests, can take a relatively long time.

Case Study

Highway Investigation Works Adjacent to Live Highway, Cornwall

In-situ California Bearing Ratio (CBR) testing was undertaken to provide a design CBR value for road pavement design.

The testing was to be undertaken within a highway verge of an existing A-road. Ruddlesden geotechnical obtained the necessary street works licence and organised the appropriate level of traffic management to protect site operatives.

Trial pits were excavated within the verge to reveal the underlying subgrade. A number of Transport Research Laboratory (TRL) Dynamic Cone Penetrometer (DCP) tests were undertaken to ascertain the strength of the subgrade and, combined with UKAS accredited laboratory testing, calculate a representative CBR value for design.

  • AGS
  • Constructionline
  • CSCS
  • SMAS
  • ECFC trust