80 Reinforced Earth structures, 50 000m2, 38 sites
Construction: 2007 to 2010

The Gautrain Rapid Railway was constructed by a PPP between the Gauteng Provincial Government and the Bombela Concession Company (Pty) Ltd involving Murray & Roberts Ltd. Bouygues Travaux Publics SA and Bombardier Transportation UK Ltd.

RESA designed, supplied materials and provided technical assistance to some 80 structures on 38 Sites.

The structures comprise retaining walls, both supporting and alongside the tracks, bridge abutments -road over rail, rail over road, road over river and first span viaduct abutments.

The design was undertaken together with Bombela CJV and several of its consulting engineer subcontractors. The Reinforced Earth® catered for vibration loadings; seismic accelerations of 0.3g; a service life of 100 years.

The Gautrain is powered with AC current while the Metro railway lines running alongside parts of the Gautrain are powered with DC current.

RESA proposed steel rather than synthetic reinforcing strips for the project .One of the viaduct approaches is situated near an electrical sub-station and alongside a number of DC railway tracks. The risk of electrolysis in this area was such that the use of synthetic reinforcements was required.

TerraTrel facing was selected for aesthetic reasons on one of the structures. The facing was bonded and earthed as a safeguard against electrolysis.

The constituent materials for the Reinforced Earth structures:

  • The facing elements were primarily precast concrete of which approximately one quarter had a basket weave pattern; TerraTrel facing backed with geofabric was used for the construction of several temporary structures. The precast concrete facing panels and the coping units were cast on Site by RESA. Bombela CJV provided concrete, water, electricity and a tower crane. RESA supplied 80 facing moulds and 12 coping moulds.
  • The reinforcing strips used were medium tensile, ribbed, padded, hot dip galvanized steel. GeoStrap® and Geo Mega® connections were used for the approached to a viaduct at Pretoria station where the risk of electrolysis with steel strips was deemed to be unfavourably high.
  • High resistivity weathered granite backfill meeting design specifications was used for the RE backfill

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