Traffic control method and apparatus

• US 20040204819A1
• Filed: 02/13/2004
• Published: 10/14/2004
• Est. Priority Date: 08/16/2001
• Status: Active Grant

• Current Assignee: Weiping Meng
• Original Assignee: Weiping Meng
• Inventors: Meng, Weiping
• Granted Patent: US 7,551,104 B2
• Time in Patent Office: Days
• US Class Current: 701/117
• CPC Class Codes: G08G 1/08 according to detected number or speed of vehicles

Abstract

A method called as a time-differential-ratio method and its apparatus used for intersection traffic control that differentially operates on the traffic so as to change pass-permit direction with traffic status in time is disclosed. The method includes the steps of starting, timing, vehicle-requesting, extra-moving, ratio-moving, and recycling. Unlike a common control method called as macro-estimate control method that forces changeable traffic to follow a given period and direction turn order to pass, which causes lots of stops and wait, a differential operations on the traffic are integrated with a common ratio control method and walker signals. It shows the operating features and the effective characteristic of both micro-time control and macro ratio control, which lets a vehicle arriving first pass first conditionally, is good for real-time arbitrary traffic pattern control, and leads to great reduction of stops and wait. The apparatus needed for the method includes sensing/detecting apparatuses and processing apparatus.

Claims

1. A method for intersection traffic control includes the steps of:

(1) Starting;

setting Ratio-Move as initial state; and

setting up all the other needed parameters;

(2) Time Processing;

measuring time, if a time unit is not obtained, run step (6) or (2);

(3) Vehicle Request Processing;

deciding if an Extra-Move permit is granted with reference to the state and its direction;

(4) Extra-Move Processing;

measuring Extra-Move time from the Extra-Move permitted and changing the permit when needed;

(5) Ratio-Move Processing;

measuring Ratio-Move time from the Ratio-Move permitted and changing the permit when needed;

(6) Recycling;

running step (2) directly or adding some sub-processes before it;

Said Ratio-Move is a state that follows RATIO;

Said Extra-Move is the other state that occupies some time of Ratio-Move and inserts an Extra-Direction beyond the turn order of Ratio-Directions;

Said Ratio-Direction holds a Ratio-Move permit;

Said Extra-Direction holds an Extra-Move permit;

Said permit comprises Move, Watch, and Clean;

Said permit time=move time+watch time+clean time;

Said RATIO is the most common method of intersection traffic control. It sets up a permit time for every direction according to some ratio, e.g., a ratio of north-south traffic volume over east-west;

initially after traffic-cleaning for some time, it gives the only pass-permit to a direction;

then it turns the only one permit to the next direction with its corresponding permit time in certain order from an initial direction on when the permit time of a current permitted direction runs out.

2. A method as defined in claim 1, wherein step (3) includes the sub-steps of:

(3.a) if the state is Ratio-Move and there is no vehicle-request in the Ratio-Direction, a vehicle request in another direction will receive an Extra-Move quasi-permit and certain time with a related time subtracted from the permit time of the Ratio-Direction;

if the permit time is not sufficient, the offset is subtracted from the permit time of the next Ratio-Direction with whose replacing the Ratio-Direction, set the state as Extra-Move;

Said “

there is no vehicle-request in the Ratio-Direction”

means “

, neither in its opposite”

, hereinafter;

Said quasi-permit will become an Extra-Move permit after the extra-watch time of a Ratio-Direction runs out;

Said extra-watch time is set for possible vehicles in the Ratio-Direction to brake before the permit is turned to an Extra-Direction;

it may be set 0;

Said certain time should be smaller than 10 sec or relates to the limit speed in the controlled direction;

Said related time is the sum of said certain time and extra-watch time when the Ratio-Move permit time doesn'"'"'t reach its watch time or just is the said certain time;

(3.b) skip step (3), or, if the state is Extra-Move and

(3.b.1) if there is a vehicle request in the Ratio-Direction, run step (4);

(3.b.2) skip step (3), or, if there is a vehicle request in a non-Extra-Direction and the next Extra-Direction is null, let the non-Extra-Direction be the next Extra-Direction, run step 3.b.4;

(3.b.3) skip step (3), or, keeping the permit for new vehicle requests in the Extra-Direction, and

(3.b.4) give the direction certain time with the time subtracted from the permit time of the Ratio-Direction;

if the permit time is not sufficient, the offset is subtracted from the permit time of the next Ratio-Direction with whose replacing the Ratio-Direction.

3. A method as defined in claim 1, wherein step (4) includes the sub-steps of:

(4.a) if the state is Ratio-Move, run step (5);

(4.b) if there is extra-watch time, take off one unit from it, run step (6);

otherwise, turn a quasi-permit into a Extra-Move permit, that'"'"'s, change the permit direction from the Ratio-Direction into the Extra-Direction, and set the permit as Move;

(4.c) if Extra-Move still has its permit time to run, take off one time unit from the time;

if not, if the next Extra-Direction is not null, turn the Extra-Move permit to it, i.e., let the next Extra-Direction replace the Extra-Direction and the next Extra-Direction null;

else turn the permit to the Ratio-Direction entering Ratio-Move, run step (5);

(4.d) if the Extra-Move permits time reaches Extra-Move watch time, turn the permit into Watch;

(4.e) run step (6).

4. A method as defined in claim 2, said certain time should, under the guarantee of traffic safe, with relating to the limit speed in the corresponding direction, be as small as possible, usually smaller than 10 seconds.

5. A method for intersection traffic control includes a method as defined in claim 2 and the steps of:

(21) Walk Request Processing;

deciding if a walk-permit is granted with referring to the state and its direction;

(31) Walk Processing;

measuring walk-time from walk-permit and changing the permit if needed;

Said (21) means that the step (21) should be inserted between step (2) and (3), so reasoning, (31) between (3) and (4), and (201) between (2) and (21), and (22) between (21) and (3), (211) between (21) and (22), (31) between (3) and (4), and so on;

step (xy) should be between step (x) and (x+1) also between step (x[y−

1]) and (x[y+1]) if needed. Said x and y are digits;

0-9.

6. A method as defined in claim 5, wherein step (21) includes the sub-steps of:

(21.a) if the state is Ratio-Move and permit is Move and the rest time of Move is sufficient for walker to cross, give a walk permit to any walk request in a non-Ratio-Direction with the corresponding time.

7. A method as defined in claim 5, wherein step (3) includes all the sub-steps of step (3) with its sub-steps (3.a) and (3.b.1) redefined as:

(3.a) if the state is Ratio-Move and there is no vehicle-request in the Ratio-Direction and no walk requests in the other directions, a vehicle request in another direction will receive an Extra-Move quasi-permit and the said certain time with the said related time subtracted from the permit time of the Ratio-Direction;

if the permit time is not sufficient, the offset is subtracted from the permit time of the next Ratio-Direction with whose replacing the Ratio-Direction, set the state as Extra-Move;

(3.b.1) if there is a vehicle request in the Ratio-Direction or walk requests in non-Ratio-Directions, run step (4).

8. An apparatus for intersection traffic control for a method as defined in claim 5 includes:

apparatus for vehicle requests called as Requester, analysis apparatus as Analyzer, apparatus for traffic signal display as Displayer, and apparatus for walk request called as Walk-Requester;

said Walk-requesters and said Requesters take walker'"'"'s and vehicle'"'"'s requests and send them to said Analyzer;

after analyzing these requests, Analyzer, which may be local, distributed, remote, or centered, sends the analysis results as traffic signals to Displayers in every directions;

Said Requester includes a sensing/detecting apparatus that is capable of recognizing vehicle'"'"'s distance from it within certain range;

Said Walk-requester includes a sensing/detecting apparatus that is capable of recognizing walker'"'"'s distance from it within some range;

Said Analyzer includes a Request-Inputor, a Processor, a Signal-Outputor;

said Request-Inputor collects walker'"'"'s requests from said Walk-Requesters and vehicle'"'"'s requests from said Requesters in every direction and delivers them into said Processor;

after processing, said Processor sends results to said Signal-Outputor which controls the change of traffic signals in said Displayers.

9. An apparatus as defined in claim 8, said certain range of Requesters should, under the guarantee of traffic safe, with relating to the limit speed in the corresponding direction, be as small as possible, usually smaller than 50 meters.