Gateway WA Road Project Pavement Design

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The Gateway WA project is an AUD1 billion road infrastructure project that was developed to improve the movement of traffic around in the vicinity of the airport. It is a vital link to move freight around the city.

The Leach Tonkin Interchange, one of four new interchanges constructed as part of the project, is located at the approach to the airport runway and designed to meet height restrictions to enable aircraft to land and take off safely.

This requires the roads to be constructed below groundwater level. Innovative pavement designs not previously used in WA were constructed for the three stages of immersion of the pavement into the water, including:

  • Thicklift asphalt using revised specifications to reduce moisture sensitivity and thickness by the introduction of alternative stiffer binders
  • Continuously reinforced concrete pavement at the transition to the seasonal water level
  • Contained bath structure when the pavement was below the design ground water level

A complex hydrogeology ground water model was developed to identify the immersed pavement sections. Geotechnical and structural design included waterproof slab design and tension anchors to resist uplift pressures on bath structures. The drainage team designed a sump pumping system to remove storm water from the bath structures. The new pavement specifications for the thick lift asphalt reduced pavement thicknesses and cost by 10 percent, leading to an AUD8 million saving in pavement construction.

The technical innovations of this project have been adopted as the new industry standard by Main Roads Western Australia.

GHD’s Russell Clayton was presented with a Technical Leadership award by the Australian Asphalt Pavement Association for the innovative work on this project and for contributions to the asphalt industry.



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With you, our hydrogeologists work alongside our engineers, environmental consultants, planners, surveyors and GIS consultants to arrive at integrated solutions.

GHD has global hydrogeological experience in groundwater resource assessment, aquifer storage and recovery (ASR), mine dewatering, aquifer depressurisation, groundwater management and environmental assessment, salinity, acid sulfate soils (ASS) and acid and metalliferous drainage (AMD).

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Pavement Engineering


Your single most valuable asset is arguably the pavement system within your network. We understand that pavements are subjected to static and dynamic loads as well as exposure to the elements; only sound engineering judgment, informed by experienced and qualified staff, can provide cost concious and appropriate solutions to your pavement challenges.

We demonstrate an innovative, sustainable approach through our relationships with research centres of excellence at Delft (Holland) Wisconsin (USA) Stellenbosch (South Africa) Transit New Zealand UWA (Western Australia) and ARRB (Australia).

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Road Systems


For more than 50 years, we have delivered innovative road systems including rehabilitation, expansion and development of new highways, complex interchanges, toll roads, bridges and tunnels. Our planners and engineers provide integrated services to plan, design, construct, maintain and manage all aspects of the road corridor life cycle.

From planning and procurement through to feasibility and investigation, and design, construction, delivery and maintenance, our clients enjoy bespoke solutions for roads that incorporate masterplanning, funding and economic analysis, transport planning, asset management, environmental management, risk management and more.

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We have a strong reputation, a record of accomplishment in providing world-leading technical support and advice for all areas of structural design and assessment.

Demand for GHD’s services continues to grow as the company completes and advises on a number of significant structural projects for some of the world’s tallest buildings, inlcuding Al-Bidaa Tower, Dubai Tower and the Doha Convention Center and Tower in the United Arab Emirates.

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