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US005281964A
[ii] Patent Number: 5,281,964 [45] Date of Patent: Jan. 25,1994
[54] TRAFFIC FLOW CHANGE MONITORING SYSTEM
[75] Inventors: Hideaki Iida, Tokyo; Joji Kamata, Yokohama; Ko Itoh, Machida; Masahiro Kojima, Kawasaki, all of Japan
[73] Assignee: Matsushita Electric Industrial Co., Ltd., Osaka, Japan
[21] Appl. No.: 768,295
[22] PCT Filed: Feb. 26,1991
[86] PCT No.: PCT/JP91/00244
§ 371 Date: Oct. 4,1991
§ 102(e) Date: Oct. 4,1991
[87] PCT Pub. No.: W091/13418
PCT Pub. Date: Sep. 5,1991 [30] Foreign Application Priority Data
Feb. 26, 1990 [JP] Japan 02-44900
Feb. 26, 1990 [JP] Japan 02-44901
[51] Int. C1.5 G08G 1/01
[52] U.S. Q 340/933; 340/934;
340/936; 340/937; 340/942
[58] Field of Search 340/933, 934, 936, 937,
340/941, 942, 943
[56] References Cited
U.S. PATENT DOCUMENTS
3,906,438 9/1975 Kohnert .
4,201,908 5/1980 Johnson et al. .
FOREIGN PATENT DOCUMENTS
1420636 11/1965 France .
593800 10/1977 Japan .
01- 84600 7/1989 Japan 340/933
0168398 6/1990 Japan 340/936
02- 53499 10/1990 Japan 340/934
02-84297 11/1990 Japan :. 340/934
945381 12/1963 United Kingdom . 1027880 4/1966 United Kingdom .
OTHER PUBLICATIONS
Peter Uriot, et al "Das Optimum finden, Anwendungsbeispiel: Verkehrsfluss-Messystem fur Schnellstrassen", Elektronik, vol. 34, No. 16, Aug. 9, 1985, pp. 77-82.
Primary Examiner—John K. Peng
Assistant Examiner—Nina Tong
Attorney, Agent, or Firm—Stevens, Davis, Miller &
Mosher
[57] ABSTRACT
A traffic flow change monitoring system is disclosed, which uses data obtained from a vehicle perceiving sensor placed on a road and which can detect a traffic congestion or an unexpected event. Since a change in traffic flow is monitored on the basis of the speeds or the like of individual vehicles and the distances between successive vehicles, it is possible to monitor a positional relationship between successively running vehicles Also, it is possible to make a prompt detection of an unexpected event such as an accident by detecting a change in relative vehicle speed difference between traffic lanes at each measurement spot.
2 Claims, 4 Drawing Sheets
