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A simpler way to navigate

South Australia’s road network includes an alphanumeric route system—providing you with a simpler way to navigate our State.

The letter and number system is designed to help you navigate your next road trip with ease. Simply look for and follow the yellow letters and numbers on our green road signs to reach South Australian destinations, without having to remember multiple road names.

The alphanumeric route system has been in place since 1997 and, as our road network grows and more popular travel paths are identified, new alphanumeric routes are added to continuously update this navigational network.

Why use and navigate with the alphanumeric route system?

Understanding the system will improve your travel by:

  • making it easier to find popular tourist destinations
  • guiding you through areas in Adelaide and South Australia that you are less familiar with
  • providing a backup navigational system for when your GPS or other navigational tool doesn’t work.

Travel paths linking useful, popular locations or areas of significance are given a unique alphanumeric name. Instead of needing to follow a series of roads or streets to find a destination, road users can refer to the alphanumeric letter and number which will take them to, or near, the area they want to reach.

Examples:
When planning your next road trip, you could hop on the A1 to get to Port Wakefield or take the A13 to Victor Harbor.
If you are a South Australian road user travelling across the city for work, you could take the M2, also known as the North-South Motorway, which runs from Gawler in the north to Noarlunga in the south.

Google Maps also uses this system, both here and interstate—the letter-and-number combination in Google Maps directions match our signs to help you navigate your travel without referring to a map.

Signs are clearly visible at the start and end of various routes with additional signs at junctions along the way, so you can join a route or be reassured you are still on the right road.

What do the letters and numbers mean?

The letter in the alphanumeric route system references the road classification, while the numbers are unique identifiers for each route. Learn about each route type using the tabs below.

M
is a motorway or expressway
These roads keep traffic moving and are likely to have no traffic lights and higher speed limits.
A
is a main or arterial route
These roads link to and from M roads and provide access to major towns and places of interest across metro and regional SA.
B
is a secondary or local arterial road
These roads link to and from A and M roads and provide access to places of interest across metro and regional SA.
C
is a major collector road
These roads link local roads and streets to the arterial road network for inter-state travel.
R
is for the Adelaide city ring route
These roads provide a path around the city, rather than travelling through it.

Click on the interactive map to view the five different route classifications in South Australia and where these roads take you.

Use the filters Filter icon on the map to toggle between route types.