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?