Traffic signal control apparatus optimizing signal control parameter by rolling horizon scheme

• US 6,339,383 B1
• Filed: 11/03/2000
• Issued: 01/15/2002
• Est. Priority Date: 11/05/1999
• Status: Expired due to Term

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Kobayashi, Masafumi, Usami, Tsutomu, Oota, Toshifumi
• Primary Examiner(s): Lefkowitz, Edward
• Application Number:
  US09/704,574
• Time in Patent Office: 438 Days
• Field of Search: 340/907, 340/909, 340/910, 340/916, 340/917, 701/117, 701/118, 701/119
• US Class Current: 340/907
• CPC Class Codes: G08G 1/08 according to detected number or speed of vehicles
• CPC Class Codes: G08G 1/164 Centralised systems, e.g. external to vehicles

Abstract

In a traffic signal control apparatus that can correspond to sudden change in the traffic status, traffic information is collected from a sensor provided at the road to obtain the status of a street intersection from the past to the future as profile data. By the rolling horizon scheme, optimization of the signal timing is carried out. The collect cycle of traffic information and the cycle of optimization are defined independently, and the cycle of optimization is set variable according to the cycle of signal control or the traffic status.

Claims

1. A traffic signal control apparatus comprising:

a collector unit collecting traffic information through a sensor provided at a road, and

an optimization unit predicting change in traffic status from the present to the future to optimize a signal control parameter according to a rolling horizon scheme,

wherein a collect cycle of said traffic information and a cycle of said optimization can be defined independently, and the cycle of said optimization is set variable according to a cycle of signal control or the traffic status.

2. The traffic signal control apparatus according to claim 1, wherein optimization of a signal control parameter is executed individually for each street intersection while maintaining integrity with an entire network by exchanging traffic information and signal control contents between adjacent street intersections.

3. The traffic signal control apparatus according to claim 2, further comprising a portion estimating timing of a vehicle from a traffic flow from the present to the future arriving at a stop line using a traffic flow measurement unit installed upstream a link and an estimated flow-in traffic flow amount obtained from an upstream intersection.

4. The traffic signal control apparatus according to claim 3, having a function to realize signal control taking into consideration individually or simultaneously reduction in risk of danger of a traffic accident, influence to an environment, and reduction of stops at a signal of a bus and other public transportation.

5. The traffic signal control apparatus according to claim 4, having a self correction function to correct estimated flow-out amount according to a relationship between history of a traffic signal light color and traffic volume measured by a traffic flow measurement device of a flow-out destination link.

6. The traffic signal control apparatus according to claim 5, having a function to correct an estimated traffic jam length according to a jam length measured by an image sensor or a jam length calculated from traffic information obtained by the traffic flow measurement device.

7. The traffic signal control apparatus according to claim 6, having a function to alter a weight coefficient of each cost element of an evaluation function of a signal control parameter according to traffic status, region characteristics and control target.

8. The traffic signal control apparatus according to claim 7, having a function to switch the control target from cost minimization to handling amount maximization, or to switch to priority control giving priority to a particular direction when traffic demand exceeding intersection processing ability flows to a street intersection.

9. The traffic signal control apparatus according to claim 8, having a function to, when excessive traffic jam occurs locally at some links, expedite a processing amount by said some links by alleviating a blue light time maximum restriction and setting a weight coefficient of downstream delay which is one cost element to 0.

10. The traffic signal control apparatus according to claim 9, including a portion to switch a signal control method according to traffic status of nonsaturation, near-saturation and over-saturation, in an abnormal status, or in response to an instruction.

11. The traffic signal control apparatus according to claim 1, further comprising a portion estimating timing of a vehicle from a traffic flow of the present to the future arriving at a stop line using a traffic flow measurement unit installed upstream a link and an estimated flow-in traffic flow amount obtained from an upstream street intersection.

12. The traffic signal control apparatus according to claim 1, having a function to realize signal control taken into consideration individually or simultaneously reduction of risk of danger of a traffic accident, influence to an environment, and number of signal stops of a bus and other public transportation.

13. The traffic signal control apparatus according to claim 1, having a self correction function to correct an estimated flow-out amount according to a relationship between history of a traffic signal light color and a traffic volume measured by a traffic flow measurement device of a flow-out destination link.

14. The traffic signal control apparatus according to claim 1, having a function to correct an estimated traffic jam length according to a jam length measured by an image sensor or a jam length calculated from a traffic information obtained by a traffic flow measurement device.

15. The traffic signal control apparatus according to claim 1, having a function to alter a weight coefficient of each cost element of an evaluation function of a signal control parameter according to traffic status, region characteristics and control target.

16. The traffic signal control apparatus according to claim 1, having a function to switch the control target from cost minimization to handling amount maximization, or to switch to priority control giving priority to a particular direction when traffic demand exceeding intersection processing ability flows to a street intersection.

17. The traffic signal control apparatus according to claim 1, having a function to, when excessive traffic jam occurs locally at some links, expedite a processing amount by said some links by alleviating a blue light time maximum restriction and setting a weight coefficient of downstream delay which is one cost element to 0.

18. The traffic signal control apparatus according to claim 1, including a portion to switch a signal control method according to traffic status of nonsaturation, near-saturation and over-saturation, in an abnormal status, or in response to an instruction.