ABSTRACT:

The Bulahdelah to Coolongolook Freeway, NSW, has been awarded as a design/construct/maintain (DCM) contract where the contractor is responsible for the design and construction of the 22 km highway and maintenance over a period of 10 years after completion of the project. One of the major criteria of the project is to control the post construction settlement of road embankments, which have been constructed as either "rockfills" or "earthfills". This paper presents the measures used to control the compaction and settlement of the fill embankments, as well as the results of field measurements and trials.

INTRODUCTION

The 22 km long Bulahdelah to Coolongolook Freeway, NSW, is part of the Pacific Highway Upgrade Program arranged by the Roads and Traffic Authority (RTA), NSW, and financed by both the Federal and State Governments. The project was awarded as a DCM (design/construct/maintain) contract and is one of the pioneering projects of this kind in NSW. The Contractor is responsible for the performance of the Deviation over a period of 10 years after completion of the project. The Deviation crosses rugged terrain where the existing landform requires major reshaping, involving cuttings up to 49m depth and fills up to 24m height. Approximately 4.8 million cubic metres of earthworks are involved including an estimated 1.3 million cubic metres of rock excavated by drilling and blasting. The materials recovered from the cuttings are used in the construction of the road embankments with an optimisation of material usage to achieve a cut/fill balance. The project is in an area underlain by complex geology including sedimentary, igneous and metamorphic rocks. The road embankments are constructed as either "rockfill" or "earthfill" embankments depending on the type of material used. Extensive field instrumentation has been installed to monitor the embankment performance during and after construction of the embankment.

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