Building the road system

Building a road

The time it takes to build a road from the concept, planning and design to construction can vary. It can take many years.

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 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 impact.

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 size of project.The stages of construction:Site preparation. Clearing buildings and vegetation. Topsoil is kept for landscaping later. Pavement is laid. First a sub-base of crushed rock or gravel, then a base of crushed rock, concrete or both. The wearing course or surface is then laid.

Landscaping takes place, often using topsoil removed in stage one. Line-markings are put down. There are sometimes delays, caused by property resumptions, funding availability, weather conditions and availability of materials.

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 (<5,000 per day):

  • This is a tar mixture with aggregate rolled into it.
  • Bitumen forms a waterproof seal.
  • It needs to be replaced around every nine years.
  • It is used extensively, including most of the Bruce Highway.

Asphalt is used on approximately 10% of state-controlled roads:

  • This can withstand heavier traffic loads but it is more expensive than sprayed bitumen.
  • It needs to be replaced around every 11 years.

Concrete is used on major highways and motorways:

  • It is the most expensive but the most durable.
  • The surface lasts around 40 years with only minor maintenance.

Last updated: 14 June 2009