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Mon 21st Apr 14

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Traffic Operations

Road Signs

Road signs help to regulate, warn and guide road users for the safe and efficient movement of traffic.

Transport is responsible for the installation and maintenance of

  • traffic signs on arterial roads
  • standard Clearway signs
  • regulatory signs on Council maintained side roads which relate to Transport SA roads.

Parking restriction signs are, however, determined and maintained by Councils.

The type and placement of road signs is very important and is carefully considered. For signs to be effective they need to
command attention
make meaning clear at a glance
allow adequate response time.

Signs and other traffic devices lose effectiveness if used unnecessarily or too frequently, so their use is restricted to the minimum consistent with safety requirements.

Application Form for Tourism and Services Road Signs

Online form.

Categories of road signs

There are 4 categories of road signs in Australia

Regulatory signs

Regulatory signs instruct road users of their legal obligations eg speed limits, prohibited or permitted movements at intersections, and parking controls.

Most regulatory signs are rectangular with a black legend on a white background.


  • stop signs (octagonal)
  • give way and roundabout signs (triangular)
  • speed restriction signs (symbol enclosed in a red circle)
  • no right hand turn signs (red slash to indicate the prohibition of a movement)
  • prohibitive parking signs (red legend on a white background)
  • permitted parking signs (green legend on a white background)

Warning signs

Warning signs indicate hazards which may not be obvious to the approaching driver.

Warning signs are a diamond shape with a black legend or symbol on a yellow background to indicate caution.

Warning signs include

  • advisory speed signs (to safely negotiate bends)
  • advance warning of traffic control devices (such as traffic lights)
  • road conditions (eg slippery when wet).

Guide signs

Guide signs inform motorists of

  • routes
  • direction and / or distance to destinations
  • points of interest and roadside facilities

Route numbering signs in the metropolitan area

Transport SA has introduced a route numbering system to South Australia.

The alpha-numeric system consistent with interstate practice complements the existing metropolitan route systems and will guide both local and visiting road users through unfamiliar areas by the most efficient routes

  • expanding residential development to the north and south means that local road users are no longer familiar with the whole of metropolitan Adelaide and it is becoming increasingly difficult to find an easy and safe route to, and through, other areas
  • changing nature of work and lifestyles has created a diversity of travel patterns and trip purposes
  • increasing number of tourists and country visitors have reported that there is a lack of directional assistance to newcomers.

The new route numbering is gradually replacing the National Highways route system in the metropolitan area. National highways are shown by the alfa-numeric number and the word National on the route number shield by the side of the road.

The route numbering marker signs are rectangular with

  • letter and number in gold on a green background
  • M for freeway or expressway
  • A for a main route
  • B for a secondary route.

Traffic signs, especially at major intersections, will gradually be modified or replaced to show the road user the

  • new route numbers.
  • name of the road being travelled.
  • name of the major crossroads being approached.
  • destinations along each leg of an intersection.

Transport SA has signposted designated routes covering the

  • metropolitan area
  • selected country areas including main tourism locations of Victor Harbor and the Barossa Valley.

Future phases will involve rural areas and outer metropolitan areas.

Route numbers give road users a short ‘burst’ of information that is easier to see and remember than changing road names, and forms part of the overall system of sign information.

A road user unfamiliar with areas of Adelaide will find it easier to arrive at their destination by using a combination of

  • route numbers
  • map
  • improved signing.


A sales representative based in Salisbury but needing to call on a potential customer in the Marion Shopping Centre would currently be advised to follow these directions

  • leave Salisbury via the Salisbury Highway to cross the Port Wakefield Road and join the South Road-Salisbury Connector to pick up South Road. Follow South Road to the junction of Sturt Road. Turn right on to Sturt Road and follow until you reach the Marion Shopping Centre.

In future, the directions could be as simple as

  • take the A13 from Salisbury, then turn right at Sturt Road.

Truck noise advisory signs

You may have noticed signs asking truck drivers to Avoid Using Noisy Exhaust Brakes around the metropolitan and country areas.

These advisory signs are

  • currently being trialed at specific locations in the urban area
  • located at strategic sites in Adelaide and the State borders
  • specifically target long distance heavy vehicle operators.

Transport SA has responded to community concern about excessive truck noise in residential areas. Noisy engine brakes are a common complaint and yet it is one of the easiest problems to fix.

Next to the USA, Australia relies on private road transport more than any other country in the world.

Use of engine brakes has become a normal driving habit but is unnecessary in most situations and especially in flat residential areas.

Transport SA is asking freight transport industry associations, owners and operators to cooperate in changing driver’s habits.

Ongoing education of the transport and freight industries is also a key platform for the success of reduced heavy vehicle noise in urban areas

A supporting information brochure has been distributed to operators to

  • raise awareness of the signs
  • increase appreciation of the need to reform driving behaviour.

With advances in technology it is expected that future auxiliary braking systems will be much quieter.

Over time noise emissions should reduce through

  • improvements to the vehicle fleet
  • changes in driver behaviour.


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