Kwinana Freeway, Cockburn Central

Kwinana Freeway is a 72km freeway in and beyond the southern suburbs of Perth, Western Australia, linking central Perth with Mandurah to the south. This particular project involved the provision of a new overbridge, Collector-Distributor roads and amendment of Kwinana Freeway on and off-ramps and local road network in the vicinity of Cockburn Central Station, South Perth.

Main Roads Western Australia (MRWA) commissioned MIEngineers to provide a concept level parallel estimate for the proposed works. We provided a first principles concept estimate for each of the components and the combined scheme.

A probabilistic estimate was also required in accordance with MRWA guidelines. Estimates were prepared using Benchmark Estimating Software to produce a probabilistic output for Base Estimates and inherent risk using Monte Carlo simulation on three point estimates at first principles. As no risk register was available, we derived contingent risk levels by applying risk profiles from similar schemes

MIEngineers’ significant parallel estimating and cost estimate negotiating experience was utilised in reconciling the estimate to under a 3% difference with the other parallel estimator.