S signaling control systems are ITS products that provide an interface between the human operator and the signalling equipment. They can be utilized for rail traffic systems, as well as road intersection traffic lights. These ITS products employ cutting edge technologies to ensure the safe passage, and flow of traffic.
According to the National Transportation Library, traffic system control systems help to coordinate individual traffic signals for overall network objectives. These signaling and control systems include the intersection traffic signals, a communications network, and a central computer management system. Coordinating the signals is managed by this central management system, and traffic officials. Furthermore, it is critical that information be shared across jurisdictions to ensure the safe flow of traffic. More modern systems can now include video surveillance, which offers more powerful traffic-control algorithms, and the possibility of predictive surveillance.
Once a traffic system is installed it can be controlled by either pretimed, or actuated operation. In pretimed operation the red, yellow, and green signals of a traffic light, for example, are pretimed at fixed intervals. On the other hand, actuated operation involves vehicle detectors, which monitor traffic at intersections. Actuated operation is mainly concerned with the green light. A green light can be terminated in actuated operation in a few different ways: the maximum green light time is met, traffic flow slows down approaching the green light, a force-off is applied, or when a priority vehicle approaches the intersection.
Interconnected signals can be achieved through distributed systems, or central systems. Distributed systems are more beneficial for projects with limited budgets. Furthermore, if wireless communications technologies must be utilized, distributed systems would work best. Keep in mind that distributed systems often do not provide real time surveillance. However, distributed systems do provide very powerful local intersection control.
Central systems, on the other hand, provide an excellent real time surveillance response time. However, they are quite expensive. Central systems can cost upwards of $80,000 per intersection. Central control systems should be utilized if your system will share data with other systems, or computer networks.
Closed loop systems are utilized in signaling control systems and consist of system detectors, local control equipment, controller master communications, on street master, central computer, and master-central communications.
Signaling control for rail transport used to be conducted via a decentralized network of control points known as signal boxes. However, with the modernization of technology, the signaling control systems are also being revamped in the digital era. Now, these decentralized systems are being consolidated into dispatch offices. Traditional signal boxes are now quite rare, and are mostly seen on heritage railways. However, some countries such as the UK, and Ireland, still use mechanical signaling to some extent. East Germany also has quite a few railway tracks that use mechanical signaling. However, for the most part, modern countries now use signal cabins, which are located near main railways stations. These control centers control the entire railway track network using electronic ITS systems.