Traffic signal control method
First Claim
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 the upper limit time is set longer with an increase of the traffic volume on an access road corresponding to a phase in question.
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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 Gmax 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.
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Citations
5 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 the upper limit time is set longer with an increase of the traffic volume on an access road corresponding to a phase in question.
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2. 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 the upper limit time is set longer with an increase in value of a sum of the traffic volume and the number of vehicles waiting on a red light per cycle on an access road corresponding to a phase in question.
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3. 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:
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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.
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4. A traffic signal control method for performing processing (a) through processing (d) as follows:
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(a) in a case where a green light time 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)/Swhere 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 λ
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.
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Specification