When setting maximum speed limits, most states and territories in Australia follow the model national road rules. Under these rules:
- Posted speed limits are capped at 110km/h
- Where there is a no speed limit posted, default speed limits are 50km/h in built-up areas, and 100km/h in rural areas
Western Australia and Northern Territory are the only two locations that don’t follow these rules. In the Northern Territory, posted speed limits can be as high as 130km/h, while default speed limits are 60km/hr for built-up areas, and 110km/h in rural areas. In Western Australia, posted speed limits are capped at 110km/h, while default speed limits are 50km/h for built-up areas, and 110km/h in rural areas.
When driving interstate, it’s also important to be aware of school zones. School zones have a speed limit of 40km/h, with the exception of South Australia where the limit is 25km/h. In South Australia, this speed limit is not only enforced in school zones, but also at children’s crossings whenever the lights are flashing.