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Road User Effects

Road User Effects. Rodrigo Archondo-Callao ETWTR. The World Bank. Motorcycle Small Car Medium Car Large Car Light Delivery Vehicle Light Goods Vehicle Four Wheel Drive Light Truck Medium Truck Heavy Truck Articulated Truck Mini-bus Light Bus Medium Bus Heavy Bus Coach. Bicycles

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Road User Effects

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  1. Road User Effects Rodrigo Archondo-CallaoETWTR The World Bank

  2. Motorcycle Small Car Medium Car Large Car Light Delivery Vehicle Light Goods Vehicle Four Wheel Drive Light Truck Medium Truck Heavy Truck Articulated Truck Mini-bus Light Bus Medium Bus Heavy Bus Coach Bicycles Rickshaw Animal Cart Pedestrian Representative Vehicles MotorizedTraffic Non-Motorized Traffic

  3. Road User Costs Models Vehicle Operating Costs • Fuel • Lubricant oil • Tire wear • Crew time • Maintenance labor • Maintenance parts • Depreciation • Interest • Overheads • Passenger time • Cargo holding time Time Costs Accidents Costs

  4. Vehicle Speed and Physical Quantities Road Roughness and Terrain and Vehicle Characteristics Vehicle Speed Unit Costs Physical Quantities Road User Costs

  5. Terrain Characteristics: Rise Plus Fall and Horizontal Curvature Vertical Profile Rise Plus Fall = (R1+R2+R3+F1+F2) / Length(meters/km) Horizontal Profile Horizontal Curvature = (C1+C2+C3+C4) / Length(degrees/km)

  6. Physical Quantities Component Quantities per Vehicle-km Fuel liters Lubricant oil liters Tire wear # of equivalent new tires Crew time hours Passenger time hours Cargo holding time hours Maintenance labor hours Maintenance parts % of new vehicle price Depreciation % of new vehicle price Interest % of new vehicle price

  7. Free-Flow Speeds Model Free speeds are calculated using a mechanistic/behavioral model and are a minimum of the following constraining velocities. • VDRIVEu and VDRIVEd = uphill and downhill velocities limited by gradient and used driving power • VBRAKEu and VBRAKEd = uphill and downhill velocities limited by gradient and used braking power • VCURVE = velocity limited by curvature • VROUGH = velocity limited by roughness • VDESIR = desired velocity under ideal conditions

  8. Free-flow Speed and Gradient VCURVE VBRAKE VROUGH VDRIVE VDESIR Speed Roughness = 3 IRI m/kmCurvature = 25 degrees/km

  9. VDRIVE DriveForce Grade Resistance Air Resistance Rolling Resistance - Driving power- Operating weight- Gradient- Density of air- Aerodynamic drag coef.- Projected frontal area- Tire type- Number of wheels - Roughness- Texture depth- % time driven on snowcovered roads- % time driven on watercovered roads

  10. VROUGH VROUGH is calculated as a function of roughness. VROUGH = ARVMAX/(a0 * RI) RI = Roughness ARVMAX = Maximum average rectified velocitya0 = Regression coefficient

  11. VDESIR VDESIR is calculated as a function of road width, roadsidefriction, non-motorized traffic friction, posted speed limit, and speed enforcement factor. VDESIR = min (VDESIR0, PLIMIT*ENFAC)PLIMIT = Posted speed limit ENFAC = Speed enforcement factor VDESIR0 = Desired speed in the absence of posted speedlimitVDESIR0 = VDES * XFRI * XNMT * VDESMUL XFRI, XNMT = Roadside and NMT factors VDESMUL = Multiplication factor VDES = Base desired speed

  12. Traffic Flow Periods To take into account different levels of traffic congestion at different hours of the day, and on different days of the week and year, HDM-4 considers the number of hours of the year (traffic flow period) for which different hourly flows are applicable. Flow Periods Flow Peak Next to Peak Medium flow Next to Low Overnight Number of Hours in the Year

  13. Passenger Car Space Equivalent (PCSE) To model the effects of traffic congestion, the mixed traffic flow is converted into equivalent standard vehicles. The conversion is based on the concept of ‘passenger car space equivalent’ (PCSE), which accounts only for the relative space taken up by the vehicle, and reflects that HDM-4 takes into account explicitly the speed differences of the various vehicles in the traffic stream.

  14. Speed Flow Model To consider reduction in speeds due to congestion, the “three-zone” model is adopted. Speed (km/hr) S1 S2 S3 S4 Sult Flow PCSE/hr Qnom Qo Qult

  15. Speed Flow Model Qo = the flow below which traffic interactions are negligibleQnom = nominal capacityQult = ultimate capacity for stable flowSnom = speed at nominal capacity (0.85 * minimum free speed)Sult = speed at ultimate capacityS1, S2, S3…. = free flow speeds of different vehicle types Speed-Flow Model Parameters by Road Type

  16. Speed Flow Types Speed (km/hr) Four Lane Wide Two Lane Two Lane Flow veh/hr

  17. Roadside Friction

  18. Congestion Modelling

  19. Effects of Speed Fluctuations(Acceleration Noise) • Vehicle interaction due to: • volume - capacity • roadside friction • non-motorised traffic • road roughness • driver behaviour & road geometry • Affects fuel consumption & operating costs

  20. dFUEL Values by Acceleration Noise and Vehicle Speed

  21. Fuel Model • Replaced HDM-III Brazil model with one based on ARRB ARFCOM model • Predicts fuel use as function of power usage

  22. Parts and Labor Costs • Usually largest single component of VOC • Function of new vehicle price and maintenance labor cost • Function of vehicle age (service life) • Function of roughness

  23. Capital Costs • Comprised of depreciation and interest costs • Depreciation based on a straight line depreciation function of the service life • HDM-4 uses ‘Optimal Life’ method or constant service life method • Optimal life method varies service life as a function of roughness

  24. Roughness on Depreciation

  25. Road Safety • HDM-4 does not predict accident rates • User defines a series of “look-up tables” of accident rates • The rates are broad, macro descriptions relating accidents to a particular set of road attributes • Fatal • Injury • Damage only

  26. Accident Rates Examples Number per 100 million vehicle-km - South Africa: Economic Warrants for Surfacing Roads, 1989, SABITA and CSIR- Canada : The Economic Appraisal of Highway Investment “Guidebook”, 1992, Ministry of Transportation

  27. Non-Motorised Transport

  28. NMT User Costs and Benefits • Travel speed and time • Wear and tear of some NMT vehicles and components • Degree of conflicts with MT traffic • Accident rates • Energy consumption

  29. Emissions Model • Hydrocarbon • Carbon monoxide • Nitrous oxides • Sulphur dioxide • Carbon dioxide • Particulates • Lead Estimate quantities of pollutants produced as a function of: • Road characteristics • Traffic volume/congestion • Vehicle technology • Fuel consumption

  30. HDM Series – Volume 4

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