road user effects the world bank rodrigo archondo-callao etwtr
TRANSCRIPT
Road User Effects
The World Bank
Rodrigo Archondo-CallaoETWTR
Representative Vehicles• 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
MotorizedTraffic
Non-Motorized Traffic
Road User Costs Models• Fuel• Lubricant oil• Tire wear• Crew time• Maintenance labor• Maintenance parts• Depreciation• Interest• Overheads
• Passenger time• Cargo holding time
Vehicle Operating Costs
Time Costs
Accidents Costs
Vehicle Speed and Physical Quantities
Road Roughness and Terrain and Vehicle Characteristics
Vehicle Speed
Physical Quantities Unit Costs
Road User Costs
Terrain Characteristics: Rise Plus Fall and Horizontal Curvature
Vertical Profile
Horizontal Profile
Rise Plus Fall = (R1+R2+R3+F1+F2) / Length(meters/km)
Horizontal Curvature = (C1+C2+C3+C4) / Length(degrees/km)
Physical Quantities
Component Quantities per Vehicle-km
Fuel litersLubricant oil litersTire wear # of equivalent new tiresCrew time hoursPassenger time hoursCargo holding time hoursMaintenance labor hoursMaintenance parts % of new vehicle priceDepreciation % of new vehicle priceInterest % of new vehicle price
Free-Flow Speeds Model
• 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
Free speeds are calculated using a mechanistic/behavioral model and are a minimum of the following constraining velocities.
Free-flow Speed and Gradient
0
50
100
150
200
250
300
-10 -8 -6 -4 -2 0 2 4 6 8 10
Gradient (%)
Spe
ed (
km/h
r)
Roughness = 3 IRI m/kmCurvature = 25 degrees/km
VCURVE
VROUGH
VDESIR
VDRIVE
VBRAKE
Speed
VDRIVE
Drive Force
Grade Resistance
Rolling Resistance
Air 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
VROUGH
VROUGH is calculated as a function of roughness.
VROUGH = ARVMAX/(a0 * RI)
RI = Roughness
ARVMAX = Maximum average rectified velocity
a0 = Regression coefficient
VDESIRVDESIR 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 limitENFAC = Speed enforcement factorVDESIR0 = Desired speed in the absence of posted speedlimit
VDESIR0 = VDES * XFRI * XNMT * VDESMUL
XFRI, XNMT = Roadside and NMT factorsVDESMUL = Multiplication factorVDES = Base desired speed
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.
PeakNext to Peak
Flow Periods
Medium flowNext to LowOvernight
Flow
Number of Hours in the Year
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.
Motorcycle 0.50 Medium Truck 1.40Small Car 1.00 Heavy Truck 1.60Medium Car 1.00 Articulated Truck 1.80Large Car 1.00 Mini-bus 1.20Light Delivery Vehicle 1.00 Light Bus 1.40Light Goods Vehicle 1.00 Medium Bus 1.50Four Wheel Vehicle 1.00 Heavy Bus 1.60Light Truck 1.30 Coach 1.70
Speed Flow Model
To consider reduction in speeds due to congestion, the “three-zone” model is adopted.
Speed (km/hr)
S1
S2
S3
Sult
Qo Qnom Qult
FlowPCSE/hr
S4
Speed Flow Model
Road Type Width (m)
Qo/ Qult
Qnom/ Qult
Qult (PCSE/h/lane)
Sult (km/h)
Single Lane Road < 4.0 0.0 0.70 600 10 Intermediate Road 4.0 to 5.5 0.0 0.70 900 20 Two Lane Road 5.5 to 9.0 0.1 0.90 1400 25 Wide Two Lane Road 9.0 to 12.0 0.2 0.90 1600 30 Four Lane Road >12.0 0.4 0.95 2000 40
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
Speed Flow Types
Speed (km/hr)
Flowveh/hr
Four Lane
Wide Two Lane
Two Lane
Roadside Friction
Congestion Modelling
Uncongested
Congested
0
Acceleration in m/s/s
Effects of Speed Fluctuations(Acceleration Noise)
Vehicle interaction due to:volume - capacity roadside frictionnon-motorised traffic road roughnessdriver behaviour & road geometry
Affects fuel consumption & operating costs
dFUEL Values by Acceleration Noise and Vehicle Speed
Vehicle Speed Acceleration Noice in m/s2Class (km/hr) 0.05 0.10 . . 0.70 0.75Car 10 0.0063 0.0701
15 0.0095 0.138620 0.0083 0.1813..
90 0.1092 0.195995 0.1133 0.1877
100 0.1255 0.1890Bus 10
1520.
Truck 1015.
Fuel Model
• Replaced HDM-III Brazil model with one based on ARRB ARFCOM model
• Predicts fuel use as function of power usage
TRACTIVE FORCESRolling, air, inertia, gradeand cornering resistance
ACCESSORIESCooling fan,
power steering,air conditioner,alternator, etc.
INTERNALENGINE
FRICTION
DRIVE - TRAININEFFICIENCIES
TOTAL POWER
ENGINE FUEL EFFICIENCY FACTOR
ESTIMATED FUEL CONSUMPTION
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
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
Roughness on Depreciation
0
1
2
3
4
5
6
7
0 5 10 15 20 25
Roughness in IRI m/km
Dep
reci
atio
n C
ost
in
Bah
t/km
.
PC LT MT
HT AT LB
MB HB MC
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
Accident Rates Examples
South Africa Gravel Road 2 Lane Paved Road
Economic Accidents 230.0 100% Accidents 100.0 100%
Evaluation w Fatality 25.0 11% w Fatality 8.0 8%
Manual w Injury 39.0 17% w Injury 27.0 27%
w Damage 166.0 72% w Damage 65.0 65%
Canada 2 Lane Paved Road 4 Lane Divided Expressway 4 Lane Freeway
British Columbia Accidents 121.0 100% Accidents 93.0 100% Accidents 50.0 100%
Economic w Fatality 1.9 2% w Fatality 1.1 1% w Fatality 0.5 1%
Evaluation w Injury 36.3 30% w Injury 30.0 32% w Injury 16.2 32%
Manual w Damage 82.8 68% w Damage 61.8 67% w Damage 33.4 67%
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
Non-Motorised Transport
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
Emissions Model
Estimate quantities of pollutants produced as a function of:– Road characteristics– Traffic
volume/congestion– Vehicle technology– Fuel consumption
– Hydrocarbon– Carbon
monoxide– Nitrous oxides– Sulphur dioxide– Carbon dioxide– Particulates– Lead
HDM Series – Volume 4