HOW SCOOT WORKS
The Kernel software at the heart of a SCOOT system is standard to all installations. The additional software (the "knitting" or UTC software) which links the SCOOT Kernel to on-street equipment and which provides the user interface is specific to the supplier.
The operation of the SCOOT model is summarised in the diagram above. SCOOT obtains information on traffic flows from detectors. As an adaptive system, SCOOT depends on good traffic data so that it can respond to changes in flow. Detectors are normally required on every link. Their location is important and they are usually positioned at the upstream end of the approach link. Inductive loops are normally used, but other methods are also available.
When vehicles pass the detector, SCOOT receives the information and converts the data into its internal units and uses them to construct "Cyclic flow profiles" for each link. The sample profile shown in the diagram is colour coded green and red according to the state of the traffic signals when the vehicles will arrive at the stopline at normal cruise speed. Vehicles are modelled down the link at cruise speed and join the back of the queue (if present). During the green, vehicles discharge from the stopline at the validated saturation flow rate.
The data from the model is then used by SCOOT in three optimisers which are continuously adapting three key traffic control parameters - the amount of green for each approach (Split), the time between adjacent signals (Offset) and the time allowed for all approaches to a signalled intersection (Cycle time). These three optimisers are used to continuously adapt these parameters for all intersections in the SCOOT controlled area, minimising wasted green time at intersections and reducing stops and delays by synchronising adjacent sets of signals. This means that signal timings evolve as the traffic situation changes without any of the harmful disruption caused by changing fixed time plans on more traditional urban traffic control systems.