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Operational and “Vehicular” Characteristics

Operational and “Vehicular” Characteristics. Dr. Wen Cheng, P.E., T.E., PTOE June 24 th , 2010 Cal Poly Pomona. Learning Objectives. Highway vehicle characteristics Highway traffic stream characteristics Air vehicle characteristics Waterborne Vessels Characteristics

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Operational and “Vehicular” Characteristics

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  1. Operational and “Vehicular” Characteristics Dr. Wen Cheng, P.E., T.E., PTOE June 24th, 2010 Cal Poly Pomona

  2. Learning Objectives • Highway vehicle characteristics • Highway traffic stream characteristics • Air vehicle characteristics • Waterborne Vessels Characteristics • Railway vehicles-related characteristics • Train resistance calculation

  3. Mode selection Mode choice= f (safety, convenience, price, speed, capacity) • Capacity vs. Speed • Low speed, low capacity • High speed, low capacity • Our goal is high speed, high capacity

  4. Energy consumption of transport The U.S. is an extremely mobile society. Transportation: 2/3 of petroleum, 27.5% of total energy.

  5. Propulsive efficiency of modes

  6. Highway mode-related characteristics

  7. Highway vehicles

  8. Vehicle classification adopted by FHWA

  9. Vehicle characteristics • Dimension • Width • Length • Height • Weight • Operating characteristics • Acceleration rate • Deceleration rate • Etc. • Design vehicle: selected to represent all vehicles on the highway. It is typically the largest vehicle likely to use the highway with considerable frequency. • AASHTO has designated 15 design vehicles (P, BUS, P/B, etc.)

  10. How to determine the design vehicle One road section example • Obtain the existing road use data • Predict the proportions of various vehicle types • Select the design vehicles (accommodation vs. economy) , usu. should be greater than 2% of the traffic volume

  11. Turning path for passenger car (P)

  12. Traffic stream characteristics • Speed • Volume • Density • Time headway • Space headway

  13. Travel Speed Definition: Total distance traversed divided by the travel time Units: (m/s; ft/s; mph; km/h)

  14. Three Types of Travel Speeds • Spot Speed (instantaneous speed) • Relatively short distance • Measured by laser, radar, camera, or manually by stop watch • Running Speed • Relatively long distance • Travel time: motion time only, stop-delay time excluded • Overall Speed • Relatively long distance • Travel time: motion time + stop-delay time

  15. Dash-mounted radar Hand-heldlaser Camera Stop Watch

  16. Two Types of Avg. Spot Speeds Time-mean Speed Space-mean Speed Relationship:

  17. Traffic Volume Definition: The number of vehicles that pass a roadway point per unit of time Units: (veh/day; veh/hr; veh/min; etc.)

  18. Volume-Measuring Devices Video Detector Loop Detector Tube Detector Hand-held collector

  19. Four Major Types of Travel Volumes • AADT (Annual Avg. Daily Traffic: veh/day) • Avg. # over a period of 365 days • ADT (Avg. Daily Traffic: veh/day) • Avg. # over a period less than 365 days • DHV (Design Hourly Volume: veh/hr) • Usu. 30th highest hourly volume of the design yr. • DHV=AADT(or ADT)*k • DDHV (Directional Design Hourly Volume: veh/hr) • DDHV=AADT(or ADT)*D*k

  20. Rate of Flow vs. Hourly Volume Rate of Flow Properties • Used to account for variability or peaking that may occur within 1 hr. • Each 15-min has its own rate of flow. • The peak 15-min volume is V15, peak rate of flow =4*V15

  21. Peak Hour Factor (PHF) PHF=Hourly volume/peak rate of flow=V/(4*V15) Typical value: 0.88 (rural)~0.92 (urban) Q: In what situation PHF would be 1? Numerical Example

  22. Time Headway (ht) • Definition: The time between the arrival of successive vehicles at a specified roadway point. • Avg. ht is the reciprocal of volume, if expressed in secs/veh, then:

  23. Traffic Density • Definition: The avg. # of vehicles occupying a unit length of roadway at a given instant. • Units: veh/mi; veh/km; veh/mi/ln; veh/km/ln • It is hard tophysically measure, but it can be calculated as:

  24. Space Headway (hs) • Definition: The distance between successive vehicles, typically measured from front bumper to front bumper. • Avg. hs is the reciprocal of density, if expressed in ft/veh, then:

  25. Summary of various relationships Vf, V0, s, a, t Speed, density, volume Volume, time headway Density, space headway

  26. Air Vehicles Characteristics

  27. Various transport aircrafts Boeing 707 (1950’s) Boeing 787 (2007) Airbus A-300 (1970’s) DC-9 (1980’S)

  28. STOL (short takeoff or landing) aircraft General aviation aircraft

  29. General components of aircraft

  30. Aircraft characteristics and their effects • Dimension (fuselage length, wingspan, deck height, etc.) • Design of parking area • Runway and taxiway width • Turning radii • Hangars and maintenance sheds • Weight • Pavement thickness for runways, taxiways, aprons • Capacity • Terminal size • Baggage-handling facilities • Departure lounge • Gate positions • Fuel storage • Range • Frequency of operations, mix of type, and size of aircraft

  31. Trends of aircraft characteristics • Weight: continuing growth from 1930 to present • Note: due to elaborate landing gears, there is no similar increased thickness of airfield pavements • Fuselage length: grew steadily since 1945 • Note: aircraft most likely will approach a ceiling on length as designs with_______are introduced • Wing span: has increased only slightly • Note: great news, as aprons, hangars, etc. are slightly affected • Cruising speed: 190mph (1930’s) to 1800 mph (present) • Note: increased speed give steadily decreasing marginal returns in savings of travel time (benefits vs. costs) • Runway length: due to turbofan engine, the trend of increased runway length might stop. • Passenger capacity: increase significantly • Great news or bad news?

  32. Waterborne Vessels Characteristics

  33. Passenger ship General cargo carrier Tanker carrier Inland waterway barge

  34. Shipping types Definition Tanker service: designed for carriage of bulk liquid cargoes. Liner service: relatively frequent sailings with definite and advertised schedule Nonliner service: special sailings without predetermined or fixed schedule

  35. Operating characteristics example (passenger ships)

  36. World’s merchant fleet’s status

  37. Railway vehicles-related characteristics

  38. Railway train components & types

  39. Freight car types Covered hopper hopper Auto rack car Tank car

  40. Freight car types (cont’d) Flatcar Gondola Containers Boxcar

  41. Passenger train types and characteristics • Intercity • Hold sustained speeds for relatively long time • Urban rail transit • Accelerate and decelerate constantly • Scenic tour • Recreation purpose • High speed rail (HSR) • Acela, U.S.A. • Tgv, Europe • Bullet Train, Japan • Meglev, China

  42. Train resistance

  43. Level tangent resistance AAR formula

  44. THANK YOU!!!

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