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Transportation Decision Making Principles of Project Evaluation and Programming
Chapter 15
Energy Impacts of Transportation Projects and Policies
Kumares C. Sinha and Samuel Labi
IntroductionTransportation is movement of people/freight from one point to another
Energy is needed to carry out this activity
Where does the energy come from?- Before 18 century: Energy for Land transportation -- muscles of
donkeys and horsesEnergy for Sea transportation – wind
- 18 to19 century: Steam engines- After 19 century: petroleum, electricity, etc. (petroleum is dominant)
Transportation and EnergyCURRENT ENERGY USES:
TransportationIndustrialCommercialResidential
CURRENT ENERGY SOURCES:
PetroleumElectricityNuclearWind*Solar*Plant waste (biomass)*Animal waste (biogas)*Human or animal muscle
* Renewable energy sources
Transportation and Energy (Cont’d)
Industrial37%
Transportation27%
Residential/Commercial/
Other36%
Transportation65%
Industrial25%
Residential/Commercial/
Other10%
Transportation uses up a significant fraction of all energy sources, particularly petroleum
Total Energy Use Petroleum Energy Use
Transportation and Energy (Cont’d)
Transportation’s share of petroleum use is increasing
18%
26%
Energy Use by ModeTransportation energy use by mode (2005)
Air 8%Pipeline 3%Water 4%Rail Freight 2%Rail Transit 0.4%Highway: Heavy Duty Trucks 19%
Buses 0.7%,Light Duty Vehicles 61%
Highway vehicles account for over 80% of transportation energy use.
Factors That Affect Transportation Energy Consumption
Fuel price and taxesDemand elasticity with respect to fuel price
Regulation (CAFE: Corporate Average Fuel Economy)27.5mpg for passenger cars; 20.7mpg for LDT
Vehicle sales/mixtureSUV sales, Cohort mix
Factors That Affect Transportation Energy Consumption (cont’d)
Vehicle technologyICE type, weight, alternative fuels
Road geometrygrade, curvatureHERS model
Transportation interventionNew construction, operation, preservationProject-based approach
Energy Intensity
Also known as “Energy consumption rates”
Commensurate energy unit Btu1 Btu = 1 pound of water by 1°F1 gal gasoline = 125,000 Btu; 1 gal diesel = 139,000 Btu
Energy IntensityAmount of energy needed to transport one passenger;to operate one vehicle unit
Btu per passenger-mile, Btu per vehicle-mile
Enables comparison btwn different mode, different energy source
Energy Intensity Trend by Mode
1000 Btu per vehicle-mile 1000 Btu per passenger-mile
Energy Intensity CalculationBus transit (Example)
Fuel efficiency = 7 mpg (diesel)Occupancy = 8 passengers/vehicleEnergy intensity= 1 gallon / (7·8) passenger-mile= 139,000 Btu / 56 passenger-mile= 2482 Btu/passenger-mile
EI depends not only on fuel efficiency (tech) but also occupancy (demand management)
Framework for Energy Impact AnalysisAreas of Transportation involving Energy Use
Facility construction, maintenance, and operation
Vehicle operationAmount of travelModal shiftsVehicle occupanciesFuel economies
Vehicle manufacturing and maintenance
Secondary effects due to relocation of activities
Energy Impact Estimation
Macroscopic assessmentDirect / Indirect energy consumption
Project screening level analysisChange in veh-mi, congestion level
Simulation-based analysisSpeed profile
SimTraffic example
1. Macroscopic AssessmentDirect energy consumption
Passengertransportation
Freighttransportation
Indirect energy consumption
Macroscopic Assessment Example
Highway corridor congestion mitigation projectTSM? Bus Exclusive lane construction?
Example Cont’d
Direct Energy Savings
Alt A, energy consumed by LDTs= 3,202M VMT * 5,952 Btu/veh-mi =19,059B Btu
Passengertransportation
Indirect consumption
Example Cont’d
Indirect Energy Savings
Alt C, energy consumed for roadway construction= $340M * 15,778 Btu/$ / 50 yrs = 107,290M Btu
Example Cont’d
Total Energy Savings
2. Project Screening Level Analysis (IMPACTS)
Can be done using the established relationship between congestion and fuel consumptionChange in Transportation System
Changes in VMT and Congestion
Change in Total Energy Used
FC = ∑i {CVM,i*VMi + CCD,i*CDi}FC = Change in fuel consumption in gallons;
VM = Change in VMT;
CD = Change in congestion delay in vehicle-hours;
i = Vehicle type; CVM,i and CCD,i = Coefficients
CVM,i(gals. per vehicle-
mile)
CCD,i(gals. per hr. of
delay)
Automobiles 0.04 0.42
Heavy Trucks 0.16 1.87
Buses 0.25 -
Values of CVM,i and CCD,i
– Comparison with the macroscopic analysis= 0.04 gal/veh-mi = 125,000 * 0.04 Btu/veh-mi= 5000 Btu/veh-mi (vs. 5952 Btu/veh-mi)
Project-Screening Level Example
IMPACTS spreadsheet modelhttp://www.fhwa.dot.gov/steam/impacts.htm
Transportation corridor congestion mitigation project
Bus introduction? Additional lane? Toll?
3. Simulation-Based Analysis
Kinetic information for individual vehiclesSpeed, acceleration, number of stops, etc.
Basic modelsF (gal/mile) = a0 + a1 / V (mph)
Coeff. a0, a1: Estimated through experiments
Elaborated modelsRT = RD + RI + RGRIG = RI + RGae = a + (G/100)g
Models Embedded in Traffic Simulation Packages
FREFLO
SYNCHRO
Models Embedded in Traffic Simulation Packages (cont’d)
SimTraffic10-5 gal/sec
Simulation-Based Analysis Example
Corridor Improvement Project– Signal Coordination? Left-turn bay?
Example Cont’d
Fuel consumption (gal/hr) at individual intersections
Example Cont’d
Fuel consumption along the entire corridor
Transportation energy sources –What the future holds …
High strength, light weight automotive materials
Improved efficiency of existing fuels (petroleum) through improved engines or improved fuel quality
New energy sources for vehicles - alcohol fuels (methanol and denatured ethanol)- natural gas (compressed or liquefied)- liquefied petroleum gas (LPG)- hydrogen- coal-derived liquid fuels- fuels derived from biological material- electricity (including solar energy)
Overall transportation energy consumption levels –What the future holds …
Supply side: (1) Increase diversity of energy sources (previous slide)
Increase supplyDecrease cost of energy
Demand Side:(1) Reduce energy intensities (through enhanced technology)(2) Reduce amount of travel trough
- improved commercial vehicle operations (CVO)- better system-wide traffic signal management- use of advanced traveler information systems (ATIS), - freeway incident management- travel demand management (TDM)
Questions?