Find out how the Sydney Coordinated Adaptive Traffic System (SCATS) improves traffic flow and safety for all road users.


Victoria’s traffic signals are managed by the Sydney Coordinated Adaptive Traffic System (SCATS).

SCATS is a sophisticated and dynamic intelligent transport system, and is considered one of the best traffic management systems in the world. 

SCATS was developed by traffic engineers in New South Wales in 1974. It was trialled in Melbourne in 1978 and adopted for use throughout Victoria in 1980. It is now used in almost all major cities in Australia, New Zealand and many others internationally.

In 2018, SCATS controlled more than 4,000 sets of traffic signals across Melbourne and other Victorian rural cities such as Ballarat, Bendigo, Traralgon, Geelong and Mildura.

Internationally recognised

SCATS is internationally recognised as one of the world’s best traffic signal systems and is used in about 150 cities over 27 countries, including:

  • USA
  • Brazil
  • Singapore
  • India
  • Malaysia
  • Ireland
  • South Africa
  • Fiji
  • China.

VicRoads engineers are some of the leading SCATS experts and have contributed to the development, deployment and review of SCATS systems nationally and internationally.

Learn more at VicRoads international 

How SCATS works

SCATS adapts traffic signal timing in real time to match the traffic conditions. SCATS controls 3 signal timing parameters:

  • Phase splits: green time for each movement/phase'
  • Cycle time: total time to run all movements/phases
  • Linking offsets: time difference between the start of green at nearby intersections.

In addition to counting vehicles passing in each lane, detectors also measure the density of traffic. 

These measures are reported back to the central computer at the end of every green period, then SCATS adjusts the 3 timing parameters to meet the traffic conditions.

SCATS can also decide which sites are coordinated at any point in time, although  some intersections operate more efficiently without coordination when traffic is light.

Many other signal systems around the world do not have this level of flexibility to respond to changing conditions, and instead rely on fixed time plans.


Studies have shown that optimising signal operation via SCATS has significant benefits, including reducing:

  • travel times by 21%
  • stops by 40% 
  • fuel consumption by 12%.
  • With smoother traffic flow, SCATS also helps reduce road crashes.

The adaptive nature of SCATS means that the benefits are magnified during irregular conditions, such as:

  • school or public holidays
  • bad weather
  • unexpected lane closures
  • crashes and special events.


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