Design

Ground surveys help form a ‘Digital Terrain Model’ in the final design of the project.

This survey data ensures that the project better ‘fits’ the area through which it will pass, ie. that visual, landscape and noise impacts are minimal and that the road is of a high standard.

Typical features recorded by the surveyors included services (phone, electricity, water, sewer) property boundaries, nearby property improvements, vegetation (in particular the location of any threatened species), drainage paths, creeks, high flood marks, railway details, heritage details, existing highway and side roads, extent of wetlands etc. The survey data collected also provides important information for the studies such as noise modelling, flooding and hydrology.

All survey works were carried out in accordance with an Environmental Management Plan. An ecologist identified threatened and endangered species in advance of the investigation works to ensure they were not harmed.

Geotechnical investigations verified ground conditions and identified materials likely to be encountered during construction along the highway route.

Information was collected using a range of techniques (eg. test pits, bores, seismic etc) and these were used to assist in determining:

• Ground moisture conditions.
• Types, strengths and quantities of materials suitable for excavation.
• The extent of soft soils, acid sulphate soils and contaminated soils (hydrocarbon, agricultural).
• Foundation conditions for bridges and retaining walls.

A specially equipped barge was used to allow a mobile drilling rig to carefully recover core samples from below the bed of the river.

The photographs below show aspects of the initial geotechnical investigations during the design phase, for the Brunswick to Yelgun Upgrade.