THE EFFECT OF VERTICAL GEOMETRY ON VEHICULAR STREAM DYNAMICS

UPON EXAMINATION OF EXPERIMENTAL DATA OF VEHICULAR TRAFFIC FLOW THROUGH THE HOLLAND TUNNEL DURING PERIODS OF DENSE FLOW , IT WAS NOTED THAT A MARKED SIMILARITY EXISTED BETWEEN THE CYCLIC FLOW PATTERNS FOR TRAFFIC AND THE OUTPUT OF A HIGHLY RESONANT SYSTEM THAT IS SUBJECTED TO A NOISE INPUT. BASED UPON THIS SIMILARITY, AN INVESTIGATION WAS UNDERTAKEN TO DETERMINE THE DEPENDENCE OF A STREAM DYNAMICS UPON THE CHANGING LONGITUDINAL SLOPE OF THE TUNNEL ROADWAY. A DYNAMIC MODEL IS DEVELOPED WHICH RELATES THE BEHAVIOR OF THE NTH VEHICLE IN A STREAM TO THAT OF ALL N-1 PRECEDING VEHICLES. THE DERIVATION IS BASED ON TYPICAL KINEMATIC EQUATIONS FOR VERTICAL MOTION WITH THE INTERVEHICLE COUPLING PROVIDED BY A LINEAR CAR FOLLOWING RELATIONSHIP. THE LINEARIZATIONS USED ARE OF THE TYPE USUALLY ACCEPTED AS VALID APPROXIMATIONS, AND THE RESULTANT SYSTEM CHARACTERIZATION IS ONE THAT IS COMMON IN ENGINEERING ANALYSIS. AS A RESULT, IF THE MODEL ADEQUATELY DESCRIBES THE BEHAVIOR OF THE SYSTEM (AS IS BELIEVED IT DOES), A POWERFUL MODEL FOR WHICH EXHAUSTIVE ENGINEERING ANALYSIS IS POSSIBLE AND FOR WHICH EXTENSIVE UNDERSTANDING EXISTS, IS AVAILABLE FOR USE IN VEHICULAR TRAFFIC ANALYSIS. IN PARTICULAR, THE EFFECTS OF GEOMETRY AND CAR FOLLOWING ON STREAM DYNAMICS IS CLEARLY AND USABLY EXHIBITED. AS ONE OF THE RESULTS, IT IS CONCLUDED THAT A STREAM OF CARS ON THE ROADWAY OF THE HOLLAND TUNNEL CONSTITUTES A RESONANT SYSTEM IN WHICH RESONANCE IS ATTRIBUTABLE TO ROADWAY GEOMETRY. THIS RESONANCE IS MOST APPARENT TO A STATIONARY OBSERVER DURING PERIODS OF DENSE TRAFFIC WHEN THE OBSERVED VARIATION IN STREAM VELOCITY IS THE DOPPLER-SHIFTED NARROW-BAND NOISE SIGNAL THAT EXISTS IN THE STREAM DUE TO THE TUNING INHERENT IN RESONANT SYSTEMS THAT ARE SUBJECTED TO BROAD-BAND NOISE INPUTS. THE MAGNITUDE AND PERIOD OF THE OBSERVED VARIATIONAL SIGNAL ARE BOTH DIRECTLY DEPENDENT UPON THE AVERAGE SPEED OF THE STREAM. /AUTHOR/

• Supplemental Notes:
  • Vol 1, pp 139-153
• Authors:
  • Mcshane, W R
  • Yagoda, H N
• Publication Date: 0

Media Info

• Serial:
  • High Speed Ground Transportation Journal
  • Issue Number: 0

Subject/Index Terms

• TRT Terms: Analysis; Car following; Geometry; Highway traffic; Highways; Mathematical models; Slopes; Traffic; Traffic flow; Traffic speed; Travel patterns
• Uncontrolled Terms: Models; Traffic analysis; Traffic patterns
• Old TRIS Terms: Overall travel speed; Vehicular traffic
• Subject Areas: Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00227056
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS
• Created Date: Aug 13 2004 6:56PM