Sydney Chapter

Highly Constrained Railway Widening Project within a Previously Unrecorded Diatreme at Hornsby, NSW

Greg Kotze and Benjamin Rouvray

As part of the NSW Government’s Rail Clearways Program, GHD Geotechnics was the detail designer for the Hornsby Platform 5 and Stabling Project that was highly commended at the 2009 Engineering Excellence Awards. This case study relates to the widening of an existing railway embankment that is over 100 years old, under live rail traffic, located within a tightly constrained urban environment.

During the development of the detail design it became apparent that the subject site was significantly constrained by the existing embankment condition and adjacent development. These constraints prompted further detailed geotechnical investigations that revealed that the site overlies a previously unrecorded diatreme or volcanic vent.

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