A concept design for duplication of the sections of the Hume Highway to be upgraded was developed during the environmental assessment period. Following the award of the contract to the Alliance, the Northern Hume Alliance commenced further investigations to gather the data required for the development of the detailed design plans. This included site survey, geotechnical information, utility locations, and background monitoring.

As part of the concept design options, design principles were developed taking into account the RTA and Aus Road Design Guidelines. These principles included:

• Use of excavated materials for fill.
• Minimise impacts to Aboriginal heritage items and respect values.
• Minimise impacts to non-Aboriginal heritage items and respect values.
• Minimise impact to threatened species.
• Minimise impacts to native vegetation and waterways.
• Provide safe access to properties.
• Provide safe access to school buses.

Corridor Design Requirements
Design requirements for the duplication typically results in an average highway corridor width of 50 metres. However, the design takes into account constraints adjacent to the corridor and opportunities to reduce impacts on the surrounding environment. This has resulted in a variable corridor along the alignment.

Detailed design, commenced in February 2007, will be undertaken for all aspects of the project. It includes:

• Structural design including road bridges and stock underpasses.
• Environmental works and acoustic design.
• Geotechnical design including foundations, earthworks, subgrade and batters.
• Stormwater and drainage design.
• Safety design including guardrail and line marking.
• Services design including lighting, electrical design and services relocations.
• Urban and landscape design.
• Signage and roadside infrastructure.
• Local roads.
• Property adjustments.