Building roads

The time it takes to build a road from the concept, planning and design to construction varies.

Concept

The 'concept' stage can happen years ahead. It can involve working with federal and local governments, planning authorities, industry and the community.

Planning

This can take at least three to five years for major projects.

When the decision is made to build a road, the best location has to be found.

Other considerations are:

• the cost
• amount of land needed
• how it will affect the community and business
• environmental impacts.

Design

This can take one to two years for major projects. This stage decides the size, type and location of the road. Traffic volumes, type of road, general location and landscape are considered at this stage.

Construction

This can take between one and four years, depending on the size of the project.

Road layers

A major highway is typically one layer of gravel followed by four layers of asphalt or two layers of concrete. Other highways and secondary roads have three layers of gravel followed by two layers of sprayed bitumen. This can vary according to the type of ground and the expected traffic load.

Types of surfaces

• Sprayed bitumen is used for areas of lower traffic volumes (less than 5000 vehicles per day).
• Asphalt is used on approximately 10% of state-controlled roads.
• Concrete is used on major highways and motorways.