Traffic signal control method

• US 6,937,161 B2
• Filed: 04/08/2003
• Issued: 08/30/2005
• Est. Priority Date: 05/13/2002
• Status: Expired due to Fees

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Nishimura, Shigeki
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US10/408,578
• Publication Number:
  US 20030210156A1
• Time in Patent Office: 875 Days
• Field of Search: 340/907, 340/916, 340/917, 340/919, 340/921, 340/922, 340/923, 340/929, 340/933, 340/918, 701/117, 701/118, 701/119
• US Class Current: 340/917
• CPC Class Codes: G08G 1/08 according to detected number or speed of vehicles

Abstract

In traffic signal control for setting a green light time to a value between the lower limit time and the upper limit time in real time depending on a traffic volume sensed by vehicle sensors Sa, Sb, and so forth, the upper limit time G_max is set longer with an increase of a traffic volume on an access road corresponding to a phase in question (Steps T8 and T9). This arrangement is effective for use at an intersection where a traffic volume in one direction is far heavier than in any other direction, and thereby makes it possible to forestall the occurrence of traffic jam (FIG. 6).

Claims

1. A traffic signal control method for setting a green light time to a value between a lower limit time and an upper limit time in real time depending on a traffic volume sensed by a vehicle sensor, wherein:

an evaluation value is found for each phase, the evaluation value being a sum of the traffic volume in a past cycle and a set value given to the number of vehicles waiting on a red light in a case where the green light time in a last cycle had reached the upper limit time, and in a case where the green light time in the last cycle had not reached the upper limit time, the evaluation value being the traffic volume in the past cycle; and

a longer upper limit time is allocated to a phase in question as the evaluation value becomes greater, and a shorter upper limit time is allocated to the phase in question as the evaluation value becomes smaller.

3. The traffic signal control method according to either of claims 1 or 2, wherein, of a plurality of phases involved in traffic signal control at an intersection, the traffic signal control is performed for a part of the phases.

2. A traffic signal control method for performing processing (a) through processing (d) as follows:

(a) in a case where a green light dine in a last cycle had reached an upper limit time, a load factor λ

in one phase is found in accordance with an equation;

λ

=(Q+E)/S, where Q is the number of vehicles (vehicles/time) on an access road corresponding to the phase sensed in a past cycle, E is a set value given to the number of vehicles (vehicles/time) waiting on a red light on the access road corresponding to the phase, and S is a saturation traffic volume (vehicles/time) on the access road corresponding to the phase, and in a case where the green light signal in the last cycle had not reached the upper limit time, the load factor is calculated in accordance with an equation;

λ

=Q/S;

(b) the processing (a) is performed for any other phase;

(c) when the processing (a) is completed for all phases, an upper limit time for each phase is determined by distributing a value obtained by subtracting a predetermined constant time L from a maximum cycle length (fixed value) to the upper limit times in respective phases according to a ratio of the load factors λ

in the respective phases; and

(d) a green light time in a phase in question is set to a value between a lower limit time and the upper limit time, determined in the processing (c) above, in real time depending on a traffic volume sensed by a vehicle sensor.