South Australia is distinctly divided into two main areas; the well watered and populated southeastern corner and the arid outback for the rest of the state. As a result, highways are concentrated mainly in the southeast. The Eyre Highway to Perth and Stuart Highway to Darwin are the only significant highways for the remaining part of the state. The remaining roads are outback tracks. This is the list of highways in South Australia.
Since 1955 South Australia had major rural roads numbered as part of national routes and Highways. In 1998/1999 South Australia introduced "Trailblazers" with A, B and M route numbers in the Metropolitan area and tourist areas of Victor Harbour and the Barossa Valley. This system was extended to cover country areas starting in 1999/2000.
These route numbers are used on signs and maps and distinct from the four digit numbers for major roads and eight digit numbers for streets used internally by the Highways Department and later Departments of Transport to identify each road.
In South Australia, expressway may refer to a controlled access highway with no at-grade intersections or a limited access road of slightly lower standard with at-grade intersections at some locations. Currently there are three constructed expressways in Adelaide:
Although not highways as such, unsealed outback tracks form important links to remote communities and areas, the significant ones include;
Trailblazers is a new route numbering system that guides both local and visiting road users through unfamiliar areas by the most efficient routes. This brochure includes a map illustrating the 19 designated routes in the metropolitan area extending to main tourism locations of Victor Harbour and the Barossa Valley. The new signs display the route number, the name of the road being travelled on, major crossroads being approached and destinations along each leg.
In terms of each class of output to be delivered by Transport SA in the year 1999-2000, the highlights are as follows: ... extension of the route numbering system across the rural arterial network ...