Enhanced Prediction of Vehicle Fuel Economy and Other Vehicle Operating Costs (FHWA DTFH61-14-C-00044)

Transcription

1 Enhanced Prediction of Vehicle Fuel Economy and Other Vehicle Operating Costs (FHWA DTFH61-14-C-00044) ISAP Technical Committee: Pavement Field Evaluation (TC-PFE) Washington D.C. January 7, Making a world of difference. sm Slide No. 1 Overall Project Objective FHWA DTFH61-14-C to improve the state-of-the-art in vehicle operating cost estimation for use in benefit cost analysis. Vehicle Fuel Economy (FE) Non-Fuel VOCs: Tire Wear Oil Consumption Repair and Maintenance Mileage-Related Vehicle Depreciation Considerations to changes in vehicle technology, vehicle operating speeds, traffic management and driving cycles. Making a world of difference. sm Slide No. 2 Pavement Engineering & Science Program 1

2 Project Team Organization Federal Highway Administration Mr. Matthew A. Phelps, CO Mr. Valentin Vulov, COR Principal Investigators Dr. Elie Y. Hajj (PI) Dr. Peter E. Sebaaly, P.E. (Co-PI) Contracts Manager Ms. Charlene Hart, MBA, CPA, CFE, CRA Nevada Automotive Test Center Dynatest Consulting Traffic Engineering (Operations & Simulations) Dr. Hao Xu, P.E. Dr. Zong Tian, P.E. Vehicle Modeling & Simulations/Fuel Economy Dr. Muluneh Sime Mr. Gary Bailey Non-Destructive Pavement Testing & Characteristics Dr. Alvaro Ulloa Dr. Per Ullidtz Dr. Gabriel Bazi, P.E. Pavement Engineering/ Vehicle-Pavement Interaction Dr. Elie Y. Hajj Dr. Peter E. Sebaaly, P.E. Making a world of difference. sm Slide No. 3 Enhanced Prediction of Vehicle Fuel Economy & Other Vehicle Operating Costs FHWA DTFH61-14-C PHASE I: MODELING THE RELATIONSHIP BETWEEN VEHICLE SPEED AND FUEL Task 1 -- Driving Cycle Development for Controlled Access Facilities Task 2 -- Driving Cycle Development for Roadways with Partial or No Access Control Task 3 -- Fuel Consumption Estimates for Controlled Access Facilities Task 4 -- Fuel Consumption Estimates for Roadways with Partial or No Access Control Task 5 -- Phase I Report Task 6 -- Support in Implementing Phase I Equations into HERS Model PHASE II: MODELING THE RELATIONSHIP BETWEEN PAVEMENT ROUGHNESS, SPEED, ROADWAY CHARACTERISTICS AND VEHICLE OPERATING COSTS Task 7 -- Effects of Infrastructure Physical & Operating Characteristics on Non-Fuel VOC Task 8 -- The Effects of Road Curvature on Fuel Consumption Task 9 -- Incremental Fuel Consumption Due to Pavement Roughness Task Phase II Report Task Support in Implementing Phase II Equations into HERS Model Making a world of difference. sm Slide No. 4 Pavement Engineering & Science Program 2

3 Full Access Control; all access via gradeseparated interchanges PHASE I Partial Control; access via gradeseparated interchanges and direct access roadways No Access Control Source: TxDOT, Transportation Planning & Programming Division Driving Cycle Development for Controlled Access Facilities Fuel Consumption Estimates for Controlled Access Facilities PHASE I: MODELING THE RELATIONSHIP BETWEEN VEHICLE SPEED AND FUEL Source: TxDOT, Transportation Driving Cycle Development for Roadways with Partial or No Access Control Fuel Consumption Estimates for Roadways with Partial or No Access Control Source: FDOT RCI Field Handbook, Nov FE = f(as, GR, SL, NSIG) Making a world of difference. sm Slide No. 5 PHASE II MODELING THE RELATIONSHIP BETWEEN PAVEMENT ROUGHNESS, SPEED, ROADWAY CHARACTERISTICS AND VEHICLE OPERATING COSTS Effects of Infrastructure Physical and Operating Characteristics on Non- Fuel Vehicle Operating Costs The Effects of Road Curvature on Fuel Consumption Incremental Fuel Consumption Due to Pavement Roughness Making a world of difference. sm Slide No. 6 Pavement Engineering & Science Program 3

4 Vehicle Models NATC (Nevada Automotive Test Center) Vehicle fleet 30 vehicles simulated (20 chassis with different engine types) Gasoline, diesel, gasoline-ethanol blend of up to 85% ethanol (E85), hybrid-electric (HE), and liquid natural gas (LNG). Making a world of difference. sm Slide No. 7 Vehicle Models NATC (Nevada Automotive Test Center) (Cont d) Combination trucks (2 vehicles) Tractor trailer Small light duty vehicles (6 vehicles) Subcompact Compact Mid size sedan Large sedan Small SUV Minivan Large light duty vehicles (5 vehicles) Small Pickup Large SUV Class 1 truck Class 2 truck Commuter van Truck with 3 axles (1 vehicle) Vocational Dump Truck (Gravel truck) Two axle trucks with dual rear tires (3 vehicles) Class 3 truck Class 4 truck Class 5 truck Busses (3 vehicles) School bus City bus Long distance bus Making a world of difference. sm Slide No. 8 Pavement Engineering & Science Program 4

5 Fuel Economy Simulation Process Driving Cycle (Synthetically Optimized using SHRP2 NDS & ATRI) Analogous process followed for Hybrid Electric (HE) vehicles Fuel economy calculation Physics-Based Vehicle Model Model calculates fuel burn rate Road Grade Road Profile Rolling Resistance Longitudinal Profile Elevation (in) Distance (ft) Making a world of difference. sm Slide No. 9 Making a world of difference. sm Slide No. 10 Pavement Engineering & Science Program 5

6 Incremental Fuel Consumption Due to Pavement Roughness APPROACH Components of Rolling Resistance (RR) Variations in normal force exerted on pavement have direct correlation with RR. On smooth surface the variations are small & RR is affected by the deformation of the tire due to vertical load and torsional loads on the tire. On rough road surface the excitation force due to roughness can result in the loading & unloading of the tire & suspension resulting in added RR. Additional force required to overcome the RR is proportional to change in the variation in vertical forces Components of Rolling Resistance Rolling resistance force for tire running on smooth road (RR ts ) Due to tire deformation and hysteresis Additional tire rolling resistance force due to road roughness (RR ta ) Due to excitation force resulting from the unevenness of the surface & vehicle speed Rolling resistance force due to increased motion in the suspension (RR s ) Due to excitation force transmitted through the tire & power dissipated through suspension damper Making a world of difference. sm Slide No. 11 Incremental Fuel Consumption Due to Pavement Roughness APPROACH Components of Rolling Resistance (RR) Forces derived based on QCM & extending the model to full vehicle dynamics. RR ts calculated using tire hysteresis coefficient, static vertical deflection & tire rolling radius RR ta & RR s are calculated using a frequency response function (FRF) First calculate the transfer function between the road input & tire center & to sprung mass vertical response for a QCM Magnitude & phase as a function of freq. required for each tire Also requires the road input to be defined as a PSD Left to right symmetry assumed but not for aft Integrate tire response to road input over the temporal freq. range of interest Add forces: RR = RR ts + RR ta + RR S Ratio of RR to the load carried by the tire is RRC Employ RR in the formulation of the vehicle dynamics model and perform simulation over the road roughness profile (elevation vs. distance) to estimate fuel consumption. Making a world of difference. sm Slide No. 12 Pavement Engineering & Science Program 6

7 Incremental Fuel Consumption Due to Pavement Roughness APPROACH: Road Roughness Input Select 7 roads ranging from very good to very poor pavement surface condition. Calculate spatial PSD (ft^2/cycle/ft) for each from the elevation profile. Convert spatial PSD to a temporal PSD (ft^2/hz) for each speed of interest. Each temporal PSD will have a different input freq. range (i.e., higher speed = higher freq. input) Spatial PSD ( English Unit) Making a world of difference. sm Slide No. 13 Additional Tire Rolling Resistance Due to Roughness Sample transfer function between ground and front axle tire center & suspension for Compact Car Linear analysis is performed to compute a state space model, which is used to calculate transfer function Making a world of difference. sm Slide No. 14 Pavement Engineering & Science Program 7

8 Effect of Roughness on Fuel Economy Sample simulation results for Compact Car 65 Compact Car (gas) Fuel Economy % Reduction in FE Relative to Good Road as a Function of Road Roughness and Speed 0.0 Fuel Economy (mpg) Speed (mph) Good Fair(A) Fair(B) Poor(B) Poor(C) Poor(D) % Speed (mph) Fair(A) Fair(B) Poor(A) Poor(B) Poor(C) Poor(D) Although the FE change is shown for up to 90 mph, there can be limitations in achieving the higher speeds due to potential damage to the vehicle or stability and control Making a world of difference. sm Slide No. 15 Effect of Roughness on Fuel Economy Sample simulation results for a Compact Car Making a world of difference. sm Slide No. 16 Pavement Engineering & Science Program 8

9 Modeling the Relationship Between Vehicle Speed & Fuel Consumption TRB Webinar on Wednesday, March 14 from 2:00-3:30PM ET PRESENTERS: Muluneh Sime (NATC) Gary Bailey (NATC) Hao Xu (UNR) Elie Hajj (UNR) MODERATOR: Valentin Vulov (FHWA) Making a world of difference. sm Slide No. 17 Thank You! Making a world of difference. sm Slide No. 18 Pavement Engineering & Science Program 9