Published on March 3, 2014
Ali Emad Jehad P71084 KKKA 6424 INTELLIGENT URBAN TRAFFIC CONTROL SYSTEM Ir. Dr. Riza Atiq Abdullah O.K. Rahmat
is a traffic management strategy in which traffic signal timing changes, or adapts, based on actual traffic demand. This is accomplished using an adaptive traffic control system consisting of both hardware and software.
Adaptive Traffic Signal Control optimizes traffic flow by applying algorithms such as SCOOT, SCATS or ITACA to name a few. The challenge is that there can be hundreds of intersections requiring real-time connectivity to the Traffic Management Center.
MAXBAND is a portable, off-line, FORTRAN IV computer program for setting arterial signals to achieve maximal bandwidth. Special features of the program include (a) automatically choosing cycle time from a given range, (b) permitting the design speed to vary within given tolerances, (c) selecting the best lead or lag pattern for left-turn phases from a specified set, (d) allowing a queue clearance time for secondary flow accumulated during red, (e) accepting user-specified weights for the green bands in each direction, and (f) handling a simple network in the form of a three-artery triangular loop. Green splits can be provided or, alternatively, flows and capacities can be given and splits calculated by using Webster's theory. The program produces cycle time, offsets, speeds, and order of left-turn phases to maximize the weighted combination of bandwidths. The optimization uses Land and Powell's MPCODE branch and bound algorithm. As many as 12 signals can be handled efficiently. The program is available from the Federal Highway Administration.
Figure 2 shows the overall structure of the MAXBAND system. The system consists of five modules: an overall control module (MAXBAND); and four modules which handle specific subtasks (INPUT, MATGEN, MPCODE and OUTPUT). The latter four modules execute sequentially.
SCATS® is a fully adaptive urban traffic control system that optimizes traffic flow. Its self-calibrating software minimizes manual intervention, which can result in substantial operational cost savings. SCATS has been continually developed for over 40 years and sold to 27 countries, delivering real and measurable reductions in road travel times and delays.
SCATS® (Sydney Coordinated Adaptive Traffic System) is an adaptive urban traffic management system that synchronizes traffic signals to optimize traffic flow across a whole city, region or corridor. SCATS is more than just a way of linking traffic signals to provide road management coordination, it’s a sophisticated traffic engineering system that allows you to implement complex, objective-oriented, traffic management strategies.
A A SCATS-compatible Traffic Signal Controller. centralized computer system to manage all Traffic Signal Controllers. A reliable communications network for the centralized computer system to exchange data with all Traffic Signal Controllers in your city. Vehicle detectors at each intersection, usually in the form of loops in the road pavement.
SCOOT is the world's leading adaptive traffic control system. It coordinates the operation of all the traffic signals in an area to give good progression to vehicles through the network. Whilst coordinating all the signals, it responds intelligently and continuously as traffic flow changes and fluctuates throughout the day. It removes the dependence of less sophisticated systems on signal plans, which have to be expensively updated.
Information on the physical layout of the road network and how the traffic signals control the individual traffic streams are stored in the SCOOT database. Any adaptive traffic control system relies upon good detection of the current conditions in real-time to allow a quick and effective response to any changes in the current traffic situation.
SCOOT detects vehicles at the start of each approach to every controlled intersection. It models the progression of the traffic from the detector through the stop line, taking due account of the state of the signals and any consequent queues. The information from the model is used to optimize the signals to minimize the network delay.
SCOOT was originally designed to control dense urban networks, such as large towns and cities. It is also successful in small networks, especially for areas where traffic patterns are unpredictable. With over 200 systems worldwide SCOOT is working effectively in a wide range of conditions in places as diverse as big congested cities: Beijing, Bangkok and London, to small towns or networks such as: Heathrow airport and systems localised round individual junctions of the M25.
Controlled by SCOOT.
The Spanish fully adaptive system ITACA is very much a SCOOT look alike system which was developed by Sianco Traffico with the assistance of an ex Plessey engineer. ITACA has many of the characteristics of SCOOT but has been developed as one might expect in a slightly different manner. Validation is referred to as calibration, STOC values reflect discharge values, vehicles left at the end of green, max queue, journey time and a percentage weighting until correlation exercise reflecting the number of vehicles left at the end of green between street and the model output is achieved.
The placement of inductive loops or video detectors in ITACA follows the same general rules as SCOOT i.e. typically 110 meters from the stop line and at the mouth of the junction for the identification of turning vehicles. Link diagrams and Sub Areas and Regions are also defined.
RONDO, that is ROlling-horizoN based Dynamic Optimization of signal control, is a newly developed realtime traffic adaptive signal control system that aims to reduce the response delay against the sudden changes of traffic flow. RONDO project started in 1998. Since then we have added continuous enhancements to RONDO. Now, RONDO is challenging the new problems, which are to promote traffic safety and to protect the environments with keeping traffic efficiency. In this paper, we introduce the latest additional functions to solve these problems. And we have a plan to install the pilot system at the beginning of 2001. To prepare that, we have conducted two traffic field surveys. We will also introduce the simulation experiment results using the real field data.
RONDO also has the other function, which is called “the dilemma zone actuated control”. It detects the presence and the speed of the vehicle in the dilemma zone, where vehicles cannot stop at the stop-line with safety deceleration and cannot go through the intersection before the signal turns red. Then green signal is lengthened or shortened according to the information.
Fig.1 shows the image of RONDO cycle length movements, when restriction is given. The second is to use both RONDO and right-turn actuated control. It is so difficult to predict the right-turn timings of vehicles in advance correctly that RONDO cannot always control right-turn vehicles well. Therefore, RONDO entrusts right-turn vehicles handling to right-turn actuated control that lengthens and shortens right arrow phases according to the detection of the vehicles presence in right-exclusive lane.
UTOPIA is an adaptive traffic control system designed to optimize flows and give selective priority to public transport without sacrificing travel times for private traffic.
UTOPIA Urban Traffic Control System offers a wide range of strategies designed to suit any road network. In the fully adaptive mode, it constantly monitors and forecasts the traffic status and optimizes the control strategy according to flow efficiency and/or environmental criteria. This gives high performance even with unpredictable traffic conditions.
The system can assign weighted, selective or absolute priority to specific vehicles (e.g. buses/trams running behind schedule) without penalizing other traffic.
UTOPIA was developed during the 1980s. Constant innovation and enhancements have made it one of the most advanced Urban Traffic Control systems in the world. It is successfully operating in dozens of metropolitan areas today.
UTOPIA offers unmatched performance, especially in congested and unpredictable traffic conditions. Field trails have demonstrated the following benefits: 15% decrease in travel times for private traffic 50% reduction in queuing time 10% decrease in emissions and fuel consumption in urban areas. A range of strategies are available: from plan selection to traffic responsive and fully adaptive, to permit the ideal solution for each specific site.