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Title:
A SYSTEM FOR INTELLIGENT TRAFFIC CONTROL
Document Type and Number:
WIPO Patent Application WO/2014/104869
Kind Code:
A1
Abstract:
The invention provides a system that intelligently manages traffic. It is comprised of a plurality of junction servers (110a, 110b, 110c, 110d, 110e) located at the intersections being controlled. The servers communicate real time traffic data among each other via a mesh network. A central server (200) remotely updates settings and software of the junction servers (110a, 110b, 110c, 110d, 110e) but it does not control the signal timing. The junction servers (110a, 110b, 110c, 110d, 110e) determine average delays per vehicle for each movement at their respective intersections.

Inventors:
CHONG FUI THUNG DAVID (MY)
TAN BOON CHIAT (MY)
WANG SUI JIUN (MY)
LIST GEORGE (US)
Application Number:
PCT/MY2013/000046
Publication Date:
July 03, 2014
Filing Date:
March 04, 2013
Export Citation:
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Assignee:
SENA TRAFFIC SYSTEMS SDN BHD (MY)
International Classes:
G08G1/00; G08G1/07; G08G1/081; G08G1/095
Foreign References:
US20020116118A12002-08-22
US20080074289A12008-03-27
Attorney, Agent or Firm:
CHUAH, Jern Ern (Suite 609 Block D, Phileo Damansara 1,,No. 9, Jalan 16/11, Petaling Jaya, Selangor ., MY)
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Claims:
CLAIMS

1. A system of intelligent junction servers comprising:

a plurality of junction servers (1 10a, 1 10b, 1 10c, H Od, l lOe) located at various traffic intersections communicates real time traffic data between each other via a mesh network;

said junction servers (1 10a, 1 10b, 1 10c, H Od, l l Oe) determine average delays per vehicle for traffic flows associated with movements at their corresponding intersection; and

a central server (200) that remotely updates settings and data of said junction servers ( 1 10a, 1 10b, 1 10c, 1 1 Od, 1 1 Oe).

2. A system of intelligent junction servers as claimed in claim 1 , whereby said junction servers ( 1 10a, 1 1 0b, 1 10c, 1 1 Od, l l Oe) receive traffic data from adjacent junction servers ( 1 1 0a, 1 1 0b, 1 1 0c, 1 1 Od, 1 l Oe) and determine stage sequences and associated switching times that best accommodate vehicle arrivals, providing minimal delays and stops for vehicles.

3. A system of intelligent junction servers as claimed in any one of claims 1 to 2, whereby said junction servers (1 10a, 1 10b, 1 10c, 1 1 Od, l l Oe) receive traffic data about arrivals from at least one arriving vehicle and at least one upstream controller; develop an evolving switching plan; track the actual signal timing decisions relative to that plan; and passes information to neighboring controllers about their departing vehicles and switching plans.

4. A system of intelligent junction servers as claimed in any one of claims 1 to 3 , whereby said traffic data is that of traffic performance metrics such as average delay time per vehicle, percentage of green light utilization, queue length, platoon arrival times, long gaps in the arriving traffic stream, or a combination thereof.

5. A system of intelligent junction servers as claimed in any one of claims 1 to 4, whereby said junction servers (1 1 0a, 1 1 0b, 1 1 0c, 1 1 Od, 1 l Oe) independently and collectively determine switching sequences and switching times that provide minimal delays and stops for the vehicles.

6. A system of intelligent junction servers as claimed in any one of claims 1 to 5, whereby said junction servers (1 10a, 1 10b, 1 10c, H Od, H Oe) provide minimum delay trajectories by providing at least a green band for oncoming vehicles just before they arrive or soon thereafter as possible.

7. A system of intelligent junction servers as claimed in any one of claims 1 to 6, whereby said junction servers (1 10a, 1 10b, 1 10c, H Od, H Oe) use dynamic markers to convey messages with one another about when to provide green time for specific movements.

8. A system of intelligent junction servers as claimed in claim 7, whereby said dynamic marker indicates the next point in time when a subject junction controller should be commencing green for a specific movement.

9. A system of intelligent junction servers as claimed in any one of claims 7 to 8, whereby said dynamic markers are dynamic in that the time interval between successive markers is variable.

10. A system of intelligent junction servers as claimed in any one of claims 1 to 9, whereby said system employs traffic performance metrics such as average delay time per vehicle, percentage of green light utilization, queue length, platoon arrival times, long gaps in the arriving traffic stream, or a combination thereof.

1 1. A system of intelligent junction servers as claimed in any one of claims 1 to 10, whereby said system uses static markers to establish patterns of coordination between and among the intersections.

12. A system of intelligent junction servers as claimed in claim 1 1 , whereby said static markers indicate fixed intervals between a beginning of green for specific movements.

13. A system of intelligent junction servers as claimed in any one of claims 1 to

12, whereby said junction servers (1 10a, 1 10b, 1 10c, H Od, H Oe) manage traffic flow based on its last received traffic data and previously observed daily patterns when communication with other junction servers (1 10a, 1 10b, 1 10c, 1 1 Od, 1 1 Oe) is lost.

14. A system of intelligent junction servers as claimed in any one of claims 1 to

13, whereby said system employs a wireless means, a non-wireless means, or a combination to allow the central server (200) and the junction servers (1 10a, 1 10b, 1 1 0c, 1 1 Od, 1 1 Oe) to communicate with each other.

Description:
A SYSTEM FOR INTELLIGENT TRAFFIC CONTROL

TECHNICAL FIELD The technical field of the invention relates to intelligent traffic management.

BACKGROUND OF INVENTION Present traffic management systems for networks function on a cycle time model, whereby the changes of the traffic light stages at a junction are based on a predetermined, cycle-based pattern. During peak traffic periods the cycle times are increased to allow a greater volume of traffic to clear while during off peak periods the cycle times are reduced to reduce the delay time (i.e. waiting time) at a junction when the roads are clear of vehicles.

These systems are able to manage network traffic locally with the use of detectors to monitor the volume of traffic at a junction. Based on the volume of traffic the system adjusts the cycle times accordingly. However, no localized junction management system considers the traffic conditions of adjacent junctions and then capitalizes on this information.

With increases in the vehicle population especially in urban areas, there is a greater need to provide a more effective means to control traffic. There have been means to centralize the management of traffic, whereby a central server receives and processes traffic data from the network and instructs the junction nodes on how to manage traffic at their respective intersections. However, a disadvantage of such systems lies in their dependence on a central processing server. When there is a failure in the communications link between a junction node and the central processing server, management of traffic at the respective intersection deteriorates due to a lack of updated instructions. The present invention seeks to overcome the limitations of present intelligent traffic management systems.

SUMMARY OF INVENTION

The objective of the present invention is to improve the effectiveness and efficiency of traffic management systems.

The invention provides a system that intelligently manages traffic by using a plurality of intelligent junction servers located at the traffic intersections being controlled. The servers communicate real time traffic data between each other via a mesh network and use that information to control the signal timings.

Based on the data received from adjacent intersections, each junction server determines stage sequences and associated switching times that will best accommodate the vehicle arrivals. These decisions are based on traffic performance metrics such as average delay time per vehicle, percentage of green light utilization, queue length, platoon arrival times, long gaps in the arriving traffic stream, and combinations of these and possibly other metrics.

Each junction server updates its control parameter values by assessing the quality of the control it provides.

Each junction server passes information about its expected stage sequences and switching times to its neighboring controllers. It also passes information about its departing vehicles.

The junction servers create minimum delay trajectories by providing green bands for oncoming vehicles just before they arrive or soon thereafter as possible.

The junction servers manage the traffic flows at their respective intersections based on the last data received and previously recorded daily patterns when communications are lost. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 : illustrates a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Described below are preferred embodiments of the present invention with reference to the accompanying drawings. Each of the following preferred embodiments describes an example in which the intelligent traffic management system functions and provides improvements over existing prior art.

The configuration of the invention is not limited to the configuration mentioned in the following description. efering to Figure 1, an embodiment of the system is described. Junction servers (110a, 110b, 110c, 1 lOd, 1 lOe) are located at traffic intersections to collect real time traffic data and control traffic movements via signal timings. The data collected is shared with adjacent servers (110a, 110b, 110c, 1 lOd, 11 Oe) so that they can manage the traffic flows at their respective intersections (llOa, 110b, 110c, llOd, HOe). The direction of traffic flow may be departing or arriving or a combination of the two at every intersection. A central server (200) remotely updates the settings and data of the junction servers (110a, 110b, 110c, llOd, HOe) when updates become available. The central server (200) remotely tweaks the general traffic control guidance provided to the junction servers (110a, 110b, 110c, llOd, 11 Oe), such as the paths for green waves, but does not process real time data to instruct the junction servers (110a, 110b, 110c, llOd, 11 Oe) as to how to manage traffic.

The system is a decentralized traffic management system, whereby decisions are made by the junction servers (110a, 110b, 110c, llOd, llOe) independently and in parallel. This method provides greater efficiency, flexibility in determining decisions, as the junction servers (1 10a, 1 10b, 1 10c, 1 l Od, 1 l Oe) are not dependent on real-time instructions from a central server (200).

5 The junction servers ( 1 10a, 1 10b, 1 10c, 1 1 Od, 1 1 Oe) receive data from their upstream counterparts ( 1 10a, 1 10b, 1 10c, 1 1 Od, l l Oe) and individually determine stage sequences and associated switching times that will best accommodate the arriving vehicles. The data received come from at least one arriving vehicle and at least one upstream controller. Each junction server develops an evolving switching plan; and 10 tracks its actual signal timing decisions relative to that plan; and passes information to its neighboring controllers about its departing vehicles and switching plans.

Each junction server ( 1 10a, 1 10b, 1 10c, 1 1 Od, l l Oe) independently determines the switching sequences and switching times that provide minimal delays and stops for its I S arriving vehicles. Thus, it provides the best possible junction performance for the vehicles it is serving.

The junction servers ( 1 1 0a, 1 10b, 1 10c, 1 1 Od, l l Oe) provide minimum delay trajectories by providing green bands for oncoming vehicles just before they arrive or 0 soon thereafter as possible.

The system uses traffic performance metrics to determine when the stages should end and the sequence of movement combinations to service. The performance metrics are communicated between the junction servers ( 1 10a, 1 10b, 1 10c, 1 1 Od, 1 1 Oe), vehicles, 5 and upstream controllers. The following traffic performance metrics are among the most useful: average delay time per vehicle, percentage of green time utilization, queue length, platoon arrival times, long gaps in the arriving traffic stream. Other metrics can also be employed. 0 Minimizing the average delay per vehicle aims to keep all the queue lengths short and ensure that vehicles on the minor movements are serviced quickly. Queue lengths are also monitored when employing this metric. The average delay per vehicle is monitored by tracking the vehicle arrivals and departures. Total delay is computed by summing the delay for the vehicles in queue. As each vehicle departs, its delay is deleted from the total. The delay for every other vehicle is incremented as time progresses. The average delay is derived by dividing the total delay by the number of vehicles in queue.

Maximizing the percentage of green time utilization aims to keep the movement "servers" busy. Green time utilization is defined as the time required to service the vehicles divided by the duration of the green. This ensures that the processing capacity of the signal is used to the maximum extent possible, similar to minimizing the maximum average delay. It helps minimize the maximum volume-to-capacity ratio among the movements. Implementation of this metric requires the monitoring of the vehicle departures by lane and the green time durations. Monitoring the percentage of green time utilization can be implemented by utilizing vehicle actuated sensors, such as detectors at the stop bars. Vehicle actuated sensors detect the number of vehicles arriving at the stop bar during green.

Minimizing the maximum queue length aims to minimize total delay time. The maximum queue length is the difference between the total of vehicle arrivals and the total vehicle departures. When the vehicle actuated sensors are at the stop bar, gaps between vehicles are monitored between sensor actuations with each gap counted as a vehicle where the back of the queue is found when the first long gap occurs (for example more than 3 seconds).

Alternatively, if the vehicle actuated sensors are set back from the stop bar, the junction servers ( 1 10a, 1 10b, 1 10c, 1 l Od, 1 l Oe) count the number of vehicle arrivals during red, and take this as the queue length. If the upstream vehicle actuated sensors stay on during red, then the queue stretches back to at least the vehicle actuated sensor. Providing a green light when the platoon arrives at the traffic junction helps to minimize delay for all the platooned vehicles through the use of platoon arrival time. Thus, minimizing trip times, maximizing signal utilization on the main approaches, avoid delays, and minimizing traffic stops. The junction servers (1 10a, 1 10b, 1 1 0c, 1 l Od, 1 l Oe) use dynamic markers to convey messages with one another about when to provide green time for specific movements. A dynamic marker indicates the next point in time when a subject junction controller should be commencing green for a specific movement. Such markers are dynamic in that the time interval between successive markers is variable.

Long gaps in the arriving traffic stream provide opportunities for stages to end. When such long gaps occur, no vehicle is in a dilemma zone. It is especially important to find these gaps at high-speed intersections to provide sufficient warning to arriving traffic. A dilemma zone is a period of time where an approaching vehicle can neither stop short of the intersection nor pass through it before the signal turns red. It is typically 2-5 seconds before the signal turns yellow.

If a junction server ( 1 10a, 1 10b, 1 10c, 1 l Od, 1 l Oe) loses communications with other junction servers ( 1 1 0a, 1 1 0b, 1 10c, U Od, 1 l Oe) it manages traffic flow based on its last received data and previously observed daily patterns and operates independently.

The junction servers (1 10a, 1 10b, 1 10c, l l Od, H Oe) can also use static markers to establish patterns of coordination between and among the intersections. Static markers indicate fixed intervals between the beginnings of green for specific movements.

The system employs wireless means, non-wireless means, or a combination to allow the central server (200) and the junction servers ( 1 10a, 1 1 0b, 1 10c, U Od, H Oe) to communicate amongst each other. Wireless means include Wi-Fi protocols, mobile communication protocols such as, Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Wideband Code Division Multiple Access (W-CDMA), Code Division Multiple Access (CDMA), but not limited to these. In as much as the present invention is subject to many variations, modifications and changes in detail, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.