The increasing number of road users calls for new assessments and measures to manage the transportation system in the near future. In addition to that, with the current interest in the development of autonomous, cooperative and connected vehicles, management systems should develop their technologies to use the most of such advancements. (Smart) traffic signal controllers as part of intelligent transportation systems (ITS) are responsible for providing technology to improve the road user’s comfort and safety and efficiency of traffic flow at intersections and ramps. This paper reviews the main features of traffic light controllers that makes them suitable for the rapidly developing technologies of car manufacturers and expansion of data sources. As an example, traffic model predictive controller “Smart Traffic”- developed by Sweco- is introduced and applied to oversaturated intersections in Amsterdam (The Netherlands).
Traffic light controller, Automated vehicles, Model predictive controller.
Rapidly growing population demands new ways of managing transportation systems and equipping smart cities. Intelligent transportation systems(ITS) are important part of future management systems aim to enhance comfort, safety and efficiency of all transportation modes ranging from public transport to individual mobility.
ITS applications use sensor technologies, communication systems, information processing and control technology and are assimilated in vehicle manufacturing functions and large scale management applications. Traffic light controllers play a crucial role in success and effectiveness of ITS applications by regulating traffic flow at intersections to decrease the lost time, avoid dangerous situation and decrease pollution.
Traditionally, traffic lights are designed with fixed-time control where the green time and cycle length is fixed during the control time. Despite the low maintenance and high predictivity of signal schedule, fixed time controllers are not efficient and they induce a lot of unused green. The arriving pattern of vehicles is dynamically changing and the fixed time controller cannot adapt to such change of d-the arriving pattern of vehicles at the stop line for the next cycle. This kind of controller requires more data to function properly which includes far-away detectors and floating car data.
Several established systems using model-based control methods are developed and function, e.g. UTOPIA (7), OPAC (8), PRODYN (9), and RHODES (10).
The rise of intelligent technologies such as detectors, sensors, wireless communication, vehicle-to-vehicle, and vehicle-to-infrastructure communications provides a platform for model based controllers to utilize available data and perform intelligibly.
In this paper, the effect of data expansion and cooperative ITS on the new generation of traffic light controllers is discussed and elaborated. The domains that are covered in this papers are:
- Connected, cooperative and automated vehicles: this section reviews the usefulness of new (in-car) sensor technologies to improve the performance of traffic light controllers. Also the cooperation and role of traffic light controller on the performance of different level of vehicle automation is discussed.
- Integration of traffic management systems: many ITS applications are developed in the past years, e.g. route guidance(11) and variable speed advice(12). Integration of these applications and traffic light controllers are reviewed in this paper in order to synchronize large-scale management tools.
“Smart traffic” as an innovative model based controller- developed and launched by Sweco- is introduced in this paper and its main features and characteristics is reviewed. To show the capability of “Smart Traffic” in simulating over-saturated urban intersections and incorporation of new technologies (i.e. usage of floating car data), a simulation of 4 intersection in Amsterdam(the Netherlands) is carried on.