Scats scats (Sydney Coordinated Adaptive Traffic System)
Scats (Sydney Coordinated Adaptive Traffic System) is an urban traffic control system developed by Sims and others in Australia in the late 1970s and put into use in the early 1980s. Scats adopts a hierarchical control structure. Its control center is equipped with a monitoring computer and a management computer, which are connected by serial data communication lines. The regional computer automatically sends all kinds of data to the management computer. The monitoring computer continuously monitors the signal operation of all intersections and the working condition of the detector. The regional master controller is used to analyze the traffic flow data sent by the intersection controller, determine the control strategy, and carry out real-time control of each intersection in the region. At the same time, all the collected data are sent to the control center as operation records and used for offline analysis. The intersection controller mainly collects and analyzes the traffic data provided by the detector, transmits it to the regional master controller, and receives the instructions from the regional master controller to control the intersection signal. Scats adopts the control mode of on-line control at regional level, on-line control at central level and off-line control at the same time. The system goal is to maximize the comprehensive flow of similar saturation. There is no real-time traffic model. The control parameters are green signal ratio, phase difference and cycle.
Scats system, together with TRANSYT and scoot, is a representative traffic control system which has achieved good application effect in traffic practice.
In the 1980s, scats system was introduced into Shanghai, China. In the first phase, more than 20 junctions were applied, and then several junctions were installed. Up to now, Shanghai has the largest number of junctions installed in China, nearly 3500. Then, due to its excellent control concept and effect, it gradually extended to other cities.
The cities covered by scats are mainly provincial capitals or municipalities, such as Shanghai, Guangzhou, Shenyang and Tianjin. Up to 2014, about 10000 intersections have been installed in China.
There are two kinds of industrial Ethernet switches used in scats system:
Four 100m electrical ports, four 100m optical ports and two RS232 / 422 / 485 serial ports are transmitted in gigabit optical fiber
8ch 100M Ethernet port + 2ch RS232 / 422 / 485 serial port transmit in gigabit optical fiber
Scats traffic control system applications:
Scats optimal adaptive traffic system uses RS232 mode as its traffic light controller. The switch can be equipped with 8 IP HD intersection cameras, 4 of which are connected to the 100m receiver through optical fiber, corresponding to different angles of camera; Scats controls the intersection traffic light controller through RS232, and RS232 interface is connected to the traffic police command center through optical fiber and Gigabit Ethernet.
The equipment of traffic police command center is 2U card type 1ch Gigabit Ethernet + 1ch RS232 card, which can insert 17 2U cards in total and control up to 17 intersections.