A TRAFFIC ANALYZER: ITS DEVELOPMENT AND APPLICATION

THE HISTORY OF THE DEVELOPMENT AND USE OF A 2-LANE DIGITAL SPEED-PLACEMENT EQUIPMENT UNIT WHICH SERVED THE BUREAU OF PUBLIC ROADS WELL FOR TEN YEARS IS REVIEWED BRIEFLY. IN 1956 THE RECORDING CAPABILITIES OF THIS EQUIPMENT WERE INCREASED TO COVER FOUR LANES OF TRAFFIC. THE AUTOMOTIVE DIGITAL RECORDING OF DATA FOR THE TWO LANES OF TRAFFIC IN THE OLD DEVICE WAS PROVIDED BY MATCHING HAND-WOUND SOLENOIDS OVER THE KEYS OF A STANDARD ADDING MACHINE AND DEVISING A DIGITAL CLOCK TO INDICATE THE TIME OF EACH RECORDING. SOME PARTS OF THE BASIC DESIGN WERE IMPROVED WITH THE DEVELOPMENT OF EQUIPMENT TO COVER THE FOUR LANES OF TRAFFIC USING DIFFERENTLY DEVELOPED ELECTRONIC COMPONENTS. THE TRAFFIC ANALYZER DESCRIBED WAS DEVELOPED BY MODERNIZING AND REDESIGNING THE OLDER SPEED-PLACEMENT RECORDING EQUIPMENT. FIELD SETUPS ARE SHOWN OF DETECTORS ON THE FOUR-LANE DIVIDED HIGHWAY. THE SPEED DETECTORS ARE SPACED FROM 12 TO 36 FEET APART TO PROVIDE A KNOWN DISTANCE FOR SPEED TIMING. VEHICLE DETECTORS ARE CONNECTED BY EXTENSION CABLES TO PLACEMENT RELAYS AND TO SEVERAL CONTROL RELAYS FOR EACH LANE OF DATA RECORDING. THE DATA WHICH ARE AUTOMATICALLY RECORDED FOR EACH VEHICLE ARE SPEED, TRANSVERSE PLACEMENT REFERENCED TO A DESIGNATED TRAFFIC LANE, AND TIME OF DAY EACH VEHICLE PASSES THE POINT OF OBSERVATION. ALL OF THE DATA ARE RECORDED THE INSTANT THE FRONT AXLE OF EACH VEHICLE PASSES THE SECOND SPEED DETECTOR. USING AN ELECTRONIC DIGITAL COMPUTER, VEHICLE SPEED IS CALCULATED FROM THE TRAVEL TIME AND THE DISTANCE BETWEEN DETECTOR TUBES, THE POSITION OF THE CENTER OF THE VEHICLE IS COMPUTED FROM THE WHEEL PLACEMENTS, AND TIME SPACINGS BETWEEN VEHICLES ARE DETERMINED. THE COMPUTER IS ALSO USED TO DETERMINE THE SPEED AND THE TRANSVERSE AND TRANSVERSE AND LONGITUDINAL POSITIONS OF EACH VEHICLE RELATIVE TO ALL OTHER VEHICLES WHICH ARE AHEAD, BEHIND OR ADJACENT TO IT. A TECHNICAL FIELD SETUP OF THE EQUIPMENT ON A 6-LANE DIVIDED CONNECTICUT TURNPIKE IS SHOWN IN A FIGURE. SPEED, PLACEMENT AND HEADWAY DATA WERE OBTAINED FOR A TOTAL OF 183,000 MOTOR VEHICLES FOR NINE DIFFERENT CONDITIONS OF DELINEATION AND ILLUMINATION DURING DAY AND NIGHT. THE EQUIPMENT HAS BEEN USED FOR SUCH STUDIES AS THE EFFECT ON TRAFFIC OPERATION OF VARIOUS SHOULDER WIDTHS AND TYPES, THE EFFECT OF EDGE MARKING ON TRAFFIC OPERATION, LATERAL PLACEMENT GUIDES FOR THE AASHO ROAD TEST, EFFECT OF MEDIAN DIVIDERS ON DRIVER BEHAVIOR AND HIGHWAY CAPACITY, AND THE TRUCK EQUIVALENT FACTOR ON VARIOUS HIGHWAYS. MORE RECENTLY IT IS BEING UTILIZED TO DETERMINE THE RELATIVE SPACE THAT SMALL CARS OCCUPY IN THE TRAFFIC STREAM. THE ACCURACY OF THE MOBILE TRAFFIC ANALYZER UNIT HAS CAUSED IT TO BECOME RELIED UPON AS THE STANDARD MEASURE IN ITS FIELD.

• Supplemental Notes:
  • pp 263-273, 4 FIG, 11 PHOT
• Authors:
  • Taragin, A
  • Hopkins, R C
• Publication Date: 0

Media Info

• Serial:
  • Institute of Traffic Engineers Proc
  • Publisher: NATIONAL SAFETY COUNCIL

Subject/Index Terms

• TRT Terms: Analysis; Digital computers; Electronic equipment; Highway operations; Highway traffic; Measurement; Measuring instruments; Operations research; Spacing; Speed; Speed indicators; Speed measurement; Traffic; Traffic speed; Travel time; Vehicle detectors
• Uncontrolled Terms: Traffic analysis
• Old TRIS Terms: Digital systems; Electronic devices; Traffic operations research; Vehicular traffic
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00227752
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 15 2004 1:45AM