Traffic flow measuring method and apparatus

• US 5,530,441 A
• Filed: 04/05/1995
• Issued: 06/25/1996
• Est. Priority Date: 04/27/1990
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takatou, Masao, Kikuchi, Kuniyuki, Takenaga, Hiroshi, Takahashi, Kazunori, Morooka, Yasuo, Kitamura, Tadaaki, Hamada, Nobuhiro
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US08/417,275
• Time in Patent Office: 447 Days
• Field of Search: 340/937, 340/933, 340/934, 340/935, 348/113, 364/436, 364/437
• US Class Current: 340/937
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors
• CPC Class Codes: G08G 1/08 according to detected number or speed of vehicles

Abstract

A method and an apparatus for measuring traffic flows, or in other words the flows of vehicles, inside and near a crossing. The method and apparatus are capable of extracting vehicles with a high level of accuracy. Overlap of vehicles can be avoided by setting the field of a camera to exclude a range from the inflow portion to the vicinity of center of the crossing but to include a range from the center to the vicinity of the outflow portion of the crossing. Accordingly, accuracy of traffic flow measurement can be improved.

Claims

1. A method of measuring traffic flow near a crossing, comprising the steps of placing 2n cameras at an n-way crossing, with two of the cameras covering each of the n ways of the crossing;

for each way of the crossing setting the field of one of the two cameras covering the way to cover a first area which extends from an inflow portion to the vicinity of the center of the crossing, and setting the field of the other camera covering the way to cover a second area which is located in the vicinity of the center of the crossing and encompassed within said first area.

2. An apparatus for measuring traffic flow near a crossing, comprising 2n cameras positioned at an n-way crossing, and means for supplying image data from two of the 2n cameras as input data to measuring means for measuring traffic flow, the field of one of said two cameras being set to cover a first area ranging from the inflow portion to the outflow portion of said crossing and the field of the other of said two cameras being set to cover a second area near the center of the crossing and encompassed within said first area.

3. A traffic flow measuring apparatus, comprising:

image input means for taking images of scenes near a crossing;

image processing means for processing images taken by said image input means, extracting possible vehicles from the images, and providing characteristic quantities of said possible vehicles; and

measuring means for determining position data of vehicles based on said characteristic quantities obtained by said image processing means, tracking said vehicles by use of said position data, and calculating a number of vehicles moving in at least one direction of the crossing;

wherein the field of said image input means is restricted to a range from the center of said crossing to the vicinity of the outflow portion, of said at least one direction.

4. A method of measuring traffic flow near a crossing, comprising the steps of locating a camera at said crossing;

restricting the field of said camera to a range from the center portion of the crossing to the vicinity of the outflow portion of said crossing;

obtaining images with said camera; and

calculating a number of vehicles moving in at least one direction of the crossing based on the obtained images.

5. A traffic flow measuring method according to claim 4, wherein the restricting step includes setting the field of said camera to exclude a traffic signal at the crossing.

6. A traffic flow measuring apparatus comprising:

image input means for taking images of scenes near a crossing of roads;

image processing means for processing images taken by said image input means, extracting possible vehicles from the images, and providing characteristic quantities of said possible vehicles; and

measuring means for determining position data of vehicles based on said characteristic quantities obtained by said image processing means, tracking said vehicles by use of said position data, and calculating the number of vehicles moving in at least one direction of the crossing;

wherein said measuring means includes means for calculating the number of vehicles moving in each vehicle direction by use of measurement values of other traffic flow measuring apparatuses and the number of inflowing and outflowing vehicles of each road of the crossing during four time zones of a phase of the signal lights of the traffic signal controller, including a first time zone occupying time of a red signal after the passage of a preset time from the start of the red signal, a second time zone occurring after the start of a green signal, a third time zone occupying the remaining time of the green signal after passage of the second time zone and a time of a yellow signal, and a fourth time zone occurring after the start of the red signal.

7. A traffic flow measuring and controlling apparatus comprising:

image input means for taking images of scenes near a crossing of roads;

image processing means processing images taken by said image input means, extracting data representing possible vehicles, and providing characteristic quantities of said possible vehicles;

measuring means for determining position data of a vehicle based on said characteristic quantities obtained by said image processing means, tracking said vehicles by use of said position data, and calculating the number of moving vehicles in at least one direction of the crossing; and

control means for controlling a traffic signal on the basis of an output of said measuring means;

wherein said measuring means includes means for calculating the number of vehicles in each vehicle moving direction and the number of inflowing and outflowing vehicles of each road of the crossing during four time zones of a phase of the signal lights of the traffic signal controller, including a first time zone occupying time of a red signal after the passage of a preset time from the start of the red signal, a second time zone occurring after the start of a green signal, and a third time zone occupying the remaining time of the green signal after the passage of the second time zone and a time of a yellow signal.

8. A traffic flow measuring apparatus comprising:

image input means for taking images of scenes near an m-way crossing, where m is an integer greater than two;

image processing means processing images taken by said image input means, extracting information representing possible vehicles, and providing characteristic quantities of said possible vehicles;

measuring means for determining position data of vehicles based on said characteristic quantities obtained by said image processing means, tracking said vehicles by use of said position data, and calculating the number of vehicles moving in at least one direction of the crossing; and

output means for providing an output of said measuring means indicative of the calculated number of vehicles;

wherein said measuring means includes first means for measuring (m^2- 3 m+1) values, each of the (m² -3m+1) values representing the number of vehicles moving in one of the (m² -3m+1) individual directions of the m-way crossing, second means for determining the numbers of inflowing and outflowing vehicles on each of the m ways of the crossing, and third means for calculating (2m-1) values, each of the (2m-1) values representing the number of vehicles which continue in one of the moving directions by use of outputs of said first and said second means.

9. A traffic flow measuring and controlling apparatus comprising:

image input means for taking images of scenes near an m-way crossing, where m is an integer greater than two;

image processing means for processing images taken by said image input means, extracting data representing possible vehicles, and providing characteristic quantities of said possible vehicles;

measuring means for determining position data of a vehicle based on said characteristic quantities obtained by said image processing means, tracking said vehicles by use of said position data, and calculating the number of moving vehicles in at least one direction of the crossing; and

control means for controlling a signal on the basis of an output of said measuring means;

wherein said measuring means includes first means for measuring (m² -3m+1) values, each of the (m² -3m+1) values representing the number of vehicles moving in one of the (m² -3m+1) individual directions of the m-way crossing, second means for determining the numbers of inflowing and outflowing vehicles on each of the m ways of the crossing, and third means for calculating (2m -1) values, each of the (2m -1) values representing the number of vehicles which continue in one of the moving directions, by use of outputs of said first and said second means.

10. A traffic flow measuring apparatus comprising:

image input means for taking images of scenes near a m-way crossing;

image processing means for processing images taken by said image input means, extracting possible vehicles, and providing characteristic quantities of said possible vehicles;

measuring means for determining position data of vehicles based on said characteristic quantities obtained by said image processing means, tracking said vehicles by use of said position data, and calculating the number of moving vehicles in at least one direction of the crossing; and

output means for providing an output of said measuring means indicative of the calculated number of vehicles;

wherein said measuring means includes first means for determining (m² -3m+1) values, each of the (m² -3m+1) values representing the number of vehicles running in one of the (m² -3m+1) directions of the m-way crossing, second means for determining the numbers of incoming and outgoing vehicles at the m-way crossing, and third means for performing a calculation, using equations relative to volumes of traffic per signal light cycle at the m-way crossing together with values representing the numbers of vehicles running from the (m² -3m+1) individual directions to other directions and values representing the numbers of incoming and outgoing vehicles, so as to calculate values representing the numbers of vehicles which continue running in the (m² -3m+1) individual directions; and

wherein said calculation performed using equations relative to volumes of traffic per signal light cycle at the m-way crossing includes values of switching timing of a signal of a traffic signal and a delay time due to different positions of measurement for a given vehicle.

11. A traffic flow measuring apparatus comprising:

image input means for taking images of scenes near a m-way crossing;

image processing means for processing images taken by said image input means, extracting data representing possible vehicles, and providing characteristic quantities of said possible vehicles;

measuring means for determining position data of a vehicle based on said characteristic quantities obtained by said image processing means, tracking said vehicles by use of said position data, and calculating the number of moving vehicles in at least one direction of the crossing; and

control means for controlling a signal on the basis of an output of said measuring means;

wherein said measuring means includes means for determining (m² -3m+1) values, each of the (m² -3m+1) values representing the number of vehicles running in one of the (m² -3m+1) individual directions of the m-way crossing, second means for determining the numbers of incoming and outgoing vehicles at the m-way crossing, and third means for performing a calculation, using equations relative to volumes of traffic per signal light cycle at the m-way crossing together with values representing the numbers of vehicles running from the (m² -3m+1) individual directions to other directions and values representing the numbers of incoming and outgoing vehicles, so as to calculate values representing the numbers of vehicles which continue running in the individual directions; and

wherein said calculation performed using equations relative to volumes of traffic per signal light cycle at the m-way crossing includes values of switching timing of a signal of a traffic signal and a delay time due to different positions of measurement for a given vehicle.