Default speed limits
A speed limit sign often indicates the speed limit [Australian Road Rules r 20] or if there are no signs, the default speed limit applies. In a built-up area the default speed limit is 50 kph or outside of built-up areas, 100 kph [Australian Road Rules r 25].
Speed limits applying to classes of vehicles
There are also some special speed limits applying to certain classes of vehicles, for example buses exceeding 5 tonne gross vehicle mass (GVM) and vehicles exceeding 12 tonne GVM must not exceed 100 kph.
Speed limit when passing an emergency service speed zone
From 1 September 2014 drivers must also slow down and drive at a safe speed, and in any case no greater than 25 km/h when passing an emergency service speed zone.
An emergency service speed zone is an area of road in the immediate vicinity of an emergency vehicle that has stopped and is displaying a flashing blue or red light, or between 2 sets of flashing blue or red lights on a length of road on which an emergency vehicle has stopped [Road Traffic Act 1961 (SA) s 83].
The speed restriction does not apply where a person is driving on a road that is divided by a median strip and the emergency service speed zone is on the other side of the road.
Drivers are required to be alert and responsive to such situations as the speed restriction applies in any case where a police patrol car’s red and blue lights have been activated. This includes, for instance, where a driver has been pulled over by police for speeding on a freeway and the patrol car’s red and blue lights are flashing, even though this is not technically an emergency.
Drivers of emergency vehicles such as police and emergency workers are exempt from these provisions. The definition of an "emergency worker" includes members of the armed forces, the Australian Federal Police and the Australian Border Force.
Further offence of dangerous driving
Drivers who excessively speed may also be charged with an offence of dangerous driving [Road Traffic Act 1961(SA) s 46], see Dangerous driving.
Proof of speeding
Police will generally seek to prove a speeding offence through use of radar, laser devices, speed cameras or through the observation of a police officer. Speed cameras must be set up and photographs processed in accordance with the Road Traffic (Miscellaneous) Regulations 2014 (SA) [regs 32-36]. There are also provisions to allow better detection of speeding on rural highways through the use of average speed evidence [Road Traffic Act 1961 ss 79B, 175A]. Average speed evidence is calculated by measuring the speed of a vehicle between two separate speed camera locations rather than at a single point. Average speed camera locations can be situated from 14 to 50 km apart.
An expiation notice will be sent to the registered operator of the motor vehicle who must be given the opportunity to view the photograph and if she or he is not the driver, can complete a declaration nominating the actual driver. These photographs can be viewed online at: https://expiationphoto.police.sa.gov.au/ .
Other devices used to measure speed must be approved and also properly calibrated. A driver may be able to defend an offence if the police did not comply with any of these procedures, legal advice should be sought in these circumstances.
The content of the Law Handbook is made available as a public service for information purposes only and should not be relied upon as a substitute for legal advice. See Disclaimer for details. For free and confidential legal advice in South Australia call 1300 366 424.