Windsor Flood Evacuation Route, Australia

The Roads and Traffic Authority of NSW (RTA) initiated the development of a new flood evacuation route for the town of Windsor in Sydney’s north-west, which could also serve as a new arterial road.

Aurecon has been involved in this project from the outset, initially undertaking the options identification and evaluation, preparing the environmental impact statement and concept design from 2000 to 2003. This commenced with the identification of six alignment options. These options were developed and assessed in order to select the two preferred routes – one that served as a flood evacuation route and the other that provided a dual role of flood evacuation and arterial traffic relief. The assessment involved detailed environmental impact studies and concept design over the three kilometre routes.

The project team was faced with many challenges including community consultation, environmental sensitivities (wetlands, heritage and visual), soft soils and design of the flood evacuation route approximately 12 metres above the floodplain. The design of the elevated roadway required an innovative and practical approach to property access and visual impacts through residential and industrial areas and to mitigate the potential for extensive wind generated wave impacts and erosion during flood times.

Following the selection of the northern alignment as the preferred and approved route, Aurecon was commissioned to carry out the detail design and contract documentation. The approved route involved a viaduct, more than one kilometre in length, across the floodplain of South Creek with the rest of the alignment elevated via retaining walls and embankments.

During this detail design commission Aurecon undertook survey, geotechnical investigation, utility investigation, bridge and retaining wall design, road and drainage design, utilities design, flora and fauna management plans, urban and landscape design, construction staging, community consultation and contract documentation.

During construction, Aurecon also provided a technical advisory role to the RTA. This enabled any construction related design changes to be managed efficiently without any impact to the construction programme.

After years of planning and two years of construction, the Windsor Flood Evacuation Route opened in September 2007, forming the final link in providing four lanes all the way to Windsor. This combined 2.6 kilometre flood evacuation route and arterial road provides relief for congestion on Windsor Road as well as a long awaited primary flood evacuation route for the township of Windsor.