**DOT HS 812 159 June 2015**  

# Review and Analysis of Potential Safety Impacts of and Regulatory Barriers to Fuel Efficiency Technologies and Alternative Fuels In Medium- and Heavy-Duty VehiclesDISCLAIMER This publication is distributed by the U.S. Department of Transportation, National Highway Traffic Safety Administration, in the interest of information exchange. The opinions, findings, and conclusions expressed in this publication are those of the authors and not necessarily those of the Department of Transportation or the National Highway Traffic Safety Administration. The content is not intended to be used for determination of federal grant programs. The United States Government assumes no liability for its contents or use thereof. If trade or manufacturers’ names or products are mentioned, it is because they are considered essential to the object of the publication and should not be construed as an endorsement. The United States Government does not endorse products or manufacturers. Suggested APA Format Citation: Brecher, A., Epstein, A. K., & Breck, A. (2015, June). Review and analysis of potential safety impacts of and regulatory barriers to fuel efficiency technologies and alternative fuels in medium- and heavy-duty vehicles . (Report No. DOT HS 812 159). Washington, DC: National Highway Traffic Safety Administration.i TECHNICAL REPORT DOCUMENTATION PAGE 1. Report No. DOT HS 812 159 2. Government Accession No. 3. Recipient's Catalog No. 4. Title and Subtitle Review and Analysis of Potential Safety Impacts of and Regulatory Barriers to Fuel Efficiency Technologies and Alternative Fu els in Medium - and Heavy - Duty Vehicles 5. Report Date June 2015 6. Performing Organization Code 7. Author(s) Aviva Brecher, Alexander K . Epstein, & Andrew Breck 8. Performing Organization Report No. DOT - Volpe - NHTSA - 14 - 0 1 9. Performing Organization Name and Address U.S. Department of Transportation Research and Innovative Technology Administration John A. Volpe National Transportation Systems Center Cambridge, MA 02142 10. Work Unit No. (TRAIS) 11. Contract or Gra nt No. Intra - Agency Agreement HS9AA1 12. Sponsoring Agency Name and Address

National Highway Traffic Safety Administration 1200 New Jersey Ave nue SE . Washington, DC 20590 13. Type of Report and Period Covered Technical Report 14. Sponsoring Agency Code

NHTSA/NVS - 132 15. Supplementary Notes Prepared for: James MacIsaac - Contracting Officer’s Representative (COR) NHTSA Fuel Economy Division 16. Abstract This report summarizes a safety analysis of medium - and heavy - duty vehicles (MD/HDVs) equipped with fuel effici ency (FE) technologies and/or using alternative fuels (natural gas - CNG and LNG, propane, biodiesel and power train electrification). The study included a comprehensive literature review, complemented with inputs from subject matter experts (SMEs), and a sc enario - based hazard analysis. Specific FE technologies examined include: Intelligent Transportation Systems (ITS) and telematics, speed limiters, idle reduction devices, tire technologies (single - wide tires, tire pressure monitoring systems - TPMS and Automa ted Tire Inflation Systems - ATIS), aerodynamic components, long combination vehicles (LCVs) and lightweighting materials. Federal and State safety regulations, and voluntary technical standards affecting MD/HDV fleet adoption of FE technologies and alternat ive fuels were discussed, and potential regulatory barriers identified. The findings suggest that the potential safety hazards identified can be prevented or mitigated by complying with safety regulations and voluntary standards and industry best practices . The study did not identify any major regulatory barriers to rapid adoption of FE technologies and alternative fuels by the MD/HDV fleet. Note: This report was subjected to external peer review per OMB guidelines for a Highly Influential Scientific Asses sment (HISA). Materials from the peer review process are publicly available in accompanying documents . 17. Key Words Safety impacts, fuel Efficiency technologies; alternative fuels; Medium and Heavy - duty Vehicles (MD/HDVs); truck fleet; bus fleet; idle reduc tion; intelligent transportation systems (ITS); aerodynamics; tire technologies; speed limiters; Long combination vehicles (LCV); lightweighting materials; hazard scenarios; subject matter experts (SMEs); crash rates; driver training; scenario hazard anal ysis. 18. Distribution Statement Document is available to the public from the National Technical Information Service www.ntis.gov

19. Security Classif. (of this report) Unclassified 20. Security Classif. (of this page) Unclassif ied 21. No. of Pages 19 3 22. Price Form DOT F 1700.7 (8 - 72) Reproduction of completed page authorizedi i TABLE OF CONTENTS List of Tables ................................ ................................ ................................ ................................ . vi List of Figures ................................ ................................ ................................ ............................... vii Acronyms and Selected Glossary ................................ ................................ ................................ viii Acknowledgments ................................ ................................ ................................ .......................... xi Executive Summary ................................ ................................ ................................ ........................ 1 1 Introduction: Background and Objectives ................................ ................................ ............... 6 1.1 Safety Performance of the National Medium Du ty/Heavy - Duty Vehicle Fleet and Technical Approach ................................ ................................ ................................ ........ 6 1.2 National Heavy - Duty Fleet Crash Statistics and Trends ................................ ................ 9 2 Review of Liter ature on Adoption of FE Technology Clusters, Alternative Fuels, and Operational Safety of MD/HDV Fleets ................................ ................................ ................. 16 2.1 Introduction ................................ ................................ ................................ ................... 16 2.2 Adoption of Alternative Clean Fuels ................................ ................................ ............ 16 2.2.1 Natural Gas Benefits and Safety Issues ................................ ................................ .. 16 2.2.1.1 Penetration/Adoption ................................ ................................ ....................... 17 2.2.1.2 Benefits ................................ ................................ ................................ ............ 21 2.2.1.3 Safety Considerations of CNG - Fueled MD/HDVs ................................ .......... 22 2. 2.1.4 Safety Considerations for LNG - Fueled Vehicles ................................ ............ 28 2.2.1.5 Findings and Conclusions ................................ ................................ ................ 31 2.2.2 Biodiesel ................................ ................................ ................................ ................. 33 2.2.2.1 Penetration/Adoption ................................ ................................ ....................... 33 2.2.2.2 Benefits ................................ ................................ ................................ ............ 34 2.2.2.3 Safety Considerations ................................ ................................ ...................... 35 2.2.2.4 Findings and Conclusions ................................ ................................ ................ 36 2.2.3 Liquefied Petroleum Gas (Propane) ................................ ................................ ....... 36 2.2.3.1 Penetration/Adoption ................................ ................................ ....................... 37 2.2.3.2 Benefits ................................ ................................ ................................ ............ 3 8 2.2.3.3 Safety Considerations ................................ ................................ ...................... 39 2.2.3.4 Conclusions and Recommendations ................................ ................................ 40 2.3 Drivetrain Hybridization and Electrification ................................ ................................ 41 2.3.1 P enetration/Adoption ................................ ................................ .............................. 43 2.3.2 Benefits ................................ ................................ ................................ ................... 45 2.3.3 Safety Considerations ................................ ................................ ............................. 47 2.3.4 Findings and Conclusions ................................ ................................ ....................... 51 2.4 ITS and Telematics for Fuel Efficiency and Operational Safety ................................ .. 51iii 2.4.1 Driver and Vehic le Monitoring ................................ ................................ .............. 51 2.4.1.1 Penetration/Adoption ................................ ................................ ....................... 52 2.4.1.2 Benefits ................................ ................................ ................................ ............ 53 2.4.1.3 Safety Considerations ................................ ................................ ...................... 53 2.4.1.4 Findings and Conclusions ................................ ................................ ................ 54 2.5 FE Technologies Affecting Operations ................................ ................................ ........ 54 2.5.1 Speed Limiters ................................ ................................ ................................ ........ 54 2.5.1.1 Penetration and Adoption ................................ ................................ ................. 55 2.5.1.2 Benefits ................................ ................................ ................................ ............ 55 2.5.1.3 Safety Considerations ................................ ................................ ...................... 56 2.5.1.4 Findings and Conclusions ................................ ................................ ................ 59 2.5.2 Idle Reduction ................................ ................................ ................................ ......... 59 2.5.2.1 Penetration/Adoption ................................ ................................ ....................... 60 2.5.2.2 Benefits ................................ ................................ ................................ ............ 60 2.5.2.3 Safety Considerations ................................ ................................ ...................... 61 2.5.2.4 Findings and Conclusions ................................ ................................ ................ 61 2.6 Longer Combination Vehicles ................................ ................................ ...................... 61 2.6.1 Penetration/Adoption ................................ ................................ .............................. 62 2.6.2 Benefits ................................ ................................ ................................ ................... 62 2.6.3 Safety Considerations ................................ ................................ ............................. 63 2.6.4 Literature Findings ................................ ................................ ................................ . 65 2.7 Tire Technologies ................................ ................................ ................................ ......... 65 2.7.1 Tire Pressur e Monitoring Systems and Automatic Tire Inflation Systems ............ 65 2.7.1.1 Penetration/Adoption ................................ ................................ ....................... 66 2.7.1.2 Benefits ................................ ................................ ................................ ............ 66 2.7.1.3 Safety Considerations ................................ ................................ ...................... 67 2.7.1.4 Literature Findings ................................ ................................ ........................... 67 2.7.2 Single Wide Ti res ................................ ................................ ................................ ... 67 2.7.2.1 Penetration/Adoption ................................ ................................ ....................... 68 2.7.2.2 Benefits ................................ ................................ ................................ ............ 68 2.7.2.3 Safety Considerations ................................ ................................ ...................... 69 2.7.2.4 Findings and Conclusions ................................ ................................ ................ 69 2.7.3 Low Rolling Resistance Tires ................................ ................................ ................ 69 2.7.3.1 Penetration/Adoption ................................ ................................ ....................... 70 2.7.3.2 Benefits ................................ ................................ ................................ ............ 70 2.7.3.3 Safety Considerations ................................ ................................ ...................... 70 2.7.3.4 Findings and Conclusions ................................ ................................ ................ 71 2.8 Aerodynamic Components ................................ ................................ ........................... 71iv 2.8.1 Penetra tion/Adoption ................................ ................................ .............................. 71 2.8.2 Benefits ................................ ................................ ................................ ................... 73 2.8.3 Safety Considerations ................................ ................................ ............................. 74 2 .8.3.1 Side Skirts ................................ ................................ ................................ ........ 75 2.8.4 Findings and Conclusions ................................ ................................ ....................... 76 2.9 Lightweight Materials ................................ ................................ ................................ ... 77 2.9.1 Penetration/Adoption ................................ ................................ .............................. 78 2.9.2 Benefits ................................ ................................ ................................ ................... 79 2.9.3 Safety Considerations ................................ ................................ ............................. 79 2.9.4 Findings and Conclusions ................................ ................................ ....................... 80 3 Summary of Subject Matter Expert Inputs on MD/HD Safety Impacts of FE Technologies ................................ ................................ ................................ .......................... 81 3.1 Introduction: Respondents and Fleet Profiles ................................ ............................... 81 3.2 Fuel Efficiency Technology Clusters and Safety Concerns Reported .......................... 83 3.2.1 Alternative Clean Fuels ................................ ................................ .......................... 83 3.2.2 Drivetrain Hybridization and Electrification Safety ................................ ............... 85 3.2.3 Intelligent T ransportation Systems and Telematics ................................ ............... 87 3.2.4 Speed Limiters ................................ ................................ ................................ ........ 87 3.2.5 Idle Reduction (Auto Stop - Start) ................................ ................................ ............ 88 3.2.6 Driver Training: Human Factors and Operation Issues ................................ .......... 88 3.2.7 Tire Systems: Wide Base, LRR, and TPMS Safety Issues ................................ ..... 89 3.2.8 Aerodynamic Components and Safety ................................ ................................ ... 90 3.2.9 Lightweighting Materials ................................ ................................ ....................... 90 3.3 Conclusions Rega rding Key Safety Issues ................................ ................................ ... 91 4 Scenario Hazard Analysis and Prevention/Mitigation Strategies ................................ .......... 94 4.1 Technical Approach to Hazard Ana lysis of FE Technologies and Fuels in MD/HDVs ................................ ................................ ................................ ..................... 94 4.2 Scenario Analysis of Safety Hazards identified by SMEs ................................ ............ 97 4.2.1 Hazard Analy sis of CNG - Fueled Trucks and Buses ................................ .............. 97 4.2.1.1 Incidents of Vehicle Fires or Explosion Due to CNG Tank Rupture .............. 98 4.2.1.2 Rupture o f Degraded or Expired CNG Tanks ................................ .................. 99 4.2.1.3 Prevention and Mitigation of CNG Tank Failure and Refueling Hazards ..... 100v 4.2.2 Safety o f LNG - Fueled MD/HDVs and Refueling Systems ................................ .. 101 4.2.3 Flammability of Lightweighting Materials and Toxicity of Burning Byproducts ................................ ................................ ................................ ............ 103 4.2.4 Safety Performance of Single Wide Base Tires and Low - Rolling Resistance Tires ................................ ................................ ................................ ...................... 104 4.2.5 Longer Combination Trucks . . ................................ ................................ ............. 105 4.2.6 Aerodynamic Components ................................ ................................ ................... 108 4.2.7 Potential Fires from Overheated EV/PHEV Battery ................................ ............ 111 4.2.7.1 Electrical Hazards Preventi on and Mitigation ................................ ............... 113 5 Regulatory Barriers Analysis ................................ ................................ ............................... 115 5.1 Introduction ................................ ................................ ................................ ................. 115 5.2 Adoption of Alternative Clean Fuels ................................ ................................ .......... 116 5.3 Hybridization and Electrification ................................ ................................ ................ 117 5.3.1 Electric Drivetrain ................................ ................................ ................................ 117 5.3.2 Hybrid Hydraulic Drivetrain ................................ ................................ ................ 117 5.4 ITS and Telematics ................................ ................................ ................................ ..... 117 5.5 Human Factors and Operations ................................ ................................ ................... 118 5.5.1 Idle Reduction ................................ ................................ ................................ ....... 118 5.5.2 Speed limiters ................................ ................................ ................................ ....... 118 5.6 Longer Combination Vehicles and Truck Size and Weight Limits ............................ 118 5.7 Tire Technologies ................................ ................................ ................................ ....... 120 5.7.1 Tire Pressure Management Systems and Automatic Tire Inflation Systems ....... 120 5.7.2 Single Wide Tires ................................ ................................ ................................ . 121 5.7.3 Low Rolling Resistance Tires ................................ ................................ .............. 121 5.8 Aerodynamic Components ................................ ................................ ......................... 122 5.9 Lightweight Components ................................ ................................ ............................ 122 5.10 F indings and Conclusions Regarding Regulatory Barriers ................................ ......... 123 6 Conclusions and Recommendations ................................ ................................ .................... 129 7 Appendices ................................ ................................ ................................ .......................... 133 7.1 Operations/Human Factors Bibliography ................................ ................................ ... 133 7.2 Regulatory Bibliography ................................ ................................ ............................. 139 7.3 Gr een Vehicle Deployment Bibliography ................................ ................................ .. 142 7.4 Safety Bibliography ................................ ................................ ................................ .... 147 7.5 Advanced Fuels Bibliography ................................ ................................ .................... 159 7.6 Fuel Efficiency Technology Bibliography ................................ ................................ . 169vi LIST OF TABLES Table 1 - 1: FMCSA Safety Statistics 2009 - 2011. ................................ ................................ ......... 11 Table 1 - 2: Truck Fatalities in 2010 - 11 ................................ ................................ ......................... 1 2 Table 1 - 3: Estimated Numbers of Trucks in All Crashes, by Critical Reasons ............................ 12 Table 1 - 4: Alternative - Fuel Vehicles in Use by Fleet Operators: 2010 ................................ ....... 13 Table 1 - 5: Alternative - Fuel Vehicles in Use 2011 by Weight Class and Fuel Type .................... 13 Table 2 - 1: Alternative Fuel Vehicles in Use in the United States by Fleet Operators: 2010 ....... 38 Table 3 - 1: Broad Cross - Section of Subject Matter Experts Interviewed ................................ ..... 81 Table 5 - 1: Summary of Potential Regulatory Barriers for the Adoption of MD/HDV Fuel Efficiency Technologies ................................ ................................ ........................... 125vii LIST OF F IGURES Figure 1 - 1: Medium and Heavy - Duty Vehicles Types by Gross Vehicle Weight Rating (GVWR). ................................ ................................ ................................ ..................... 6 Figure 1 - 2: Heavy - duty vehicles share of national fleet, fuel consumption and GHG emissions .. 7 Figure 1 - 3: Relative potential fuel savings from six FE technologies applied to: tractor - trailers (TT), Class 3 - 6 box and bucket vehicle s, transit buses and motor coaches; Class 8 - refuse trucks; and Class 2b pickups and vans. ................................ ............................ 8 Figure 2 - 1: Estimated Consumption of Alternative Fuel by AFVs in the United States (Ref. 15) ................................ ................................ ................................ ..................... 18 Figure 2 - 2: Alternative Fueled Vehicles in Use in the United States ................................ ........... 19 Figure 2 - 3: Carbon Intensity of Various Fuels in California HDV s. ................................ ........... 22 Figure 2 - 4: CNG Tank Failures Frequencies by Cause ................................ ................................ 25 Figure 2 - 5: Prevalence of Aftermarket Conversions in CNG Failures ................................ ......... 28 Figure 2 - 6: U.S. Biodiesel Production and Consumption ................................ ............................. 34 Figure 2 - 7: Schematic of a Parallel Hybrid - Electric Utility Truck ................................ ............... 43 Figure 2 - 8: Hydraulic Hybrid Refuse Truck ................................ ................................ ................. 46 Figure 2 - 9: Smith Electric Truck ................................ ................................ ................................ .. 47 Figure 2 - 10: GreenRoad On - Board Driver Behavior and Telematics ................................ .......... 53 Figure 2 - 11: Single Wide Base Tires Replacing Duals at Each Wheel Site ................................ . 67 Figure 2 - 12: FE Technology Adoption Across Eight Major Fleets ................................ .............. 72 Figure 2 - 13: Aerodynamic Trailer Skirt Survivability to Impacts ................................ ................ 75 Figure 4 - 1: A Summary Risk Assessment Matrix Ranking and Prioritizing Hazards ................. 94 Figure 4 - 2: A Hazard Level Matrix Showing Ranked Event Probability and Consequence Severit y. ................................ ................................ ................................ ..................... 95 Figure 4 - 3: Refueling a Waste Management LNG Truck ................................ .......................... 102 Figure 4 - 4: Three Types of LCV Configurations ................................ ................................ ....... 106 Figure 4 - 5: Trailer Skirt Made From Resilient Composite Material ................................ .......... 109 Figure 5 - 1: Regulatory Environment for Longer Combination Vehicles in the United States .. 120viii ACRONYMS A ND SELECTED GLOSSARY ABS anti - lock brake system AFDC Alternative Fuels Data Center AFV alternative fueled vehicle AHSS advanced high strength steel ANL Argonne National Laboratory ANSI America n National Standards Institute APTA American Public Transportation Association APU auxiliary power unit ATIS automatic tire inflation system ATRI American Transportation Research Institute AVTA advanced vehicle testing activity BASIC Behavior Analys is and Safety Improvement Categories; a relative ranking of carriers among their peers according to safety performance, as measured by the SMS BCCS Bus Crash Causation Study BP best practice CAFE Corporate Average Fuel Economy CARB California Air Reso urces Board CC clean carrier ; a carrier that is a member of the DOE National Clean Fleets Partnership CF conventional fleet CDL commercial driver license CFRC carbon fiber reinforced composite CFRP carbon fiber reinforced plastics CMV commercial mo tor vehicle CNG compressed natural gas CO carbon monoxide CO 2 carbon dioxide CSA Compliance, Safety, Accountability; an FMCSA initiative to improve truck and bus carriers’ safety CTBSSP Commercial Truck and Bus Safety Synthesis Program DOC diesel oxid ation catalysts DOE Department of Energy DPF diesel particulate filter DTNA Daimler Truck North America EC European Commission ECM electronic control module EGR exhaust gas recirculation EIA Energy Information Administration EMT Emergency Manageme nt Technician EPA Environmental Protection Agency ESC electronic stability control ESS energy storage system EV electric vehicleix FARS Fatality Analysis Reporting System; a NHTSA database of fatal crashes FE fuel efficiency FEI fuel efficiency impr ovement FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FMCSR Federal Motor Carrier Safety Regulations FMVSS Federal Motor Vehicle Safety Standards FRP fiber reinforced plastics GEG g asoline - equivalent gallon (GEG) ; the amount of alternative fuel with equal the energy content of a gallon of gasoline GBO green bus operators ; these have signed the APTA sustainability commitment GES General Estimates System, a NHTSA crash database GGE gasoline gallon equivalent ( GGE ) ; the amount of alternative fuel that contains the energy of one gallon of gasoline GHG greenhouse gases GPS G lobal P ositioning S ystem GVWR gross vehicle weight rating H 2 hydrogen HDV heavy - duty vehicle HEV hybrid electric vehicle HHV hybrid hydraulic vehicle ICE internal combustion engine IIHS Insurance Institute for Highway Safety ISTEA Intermodal Surface Transportation Efficiency Act (1991) ITS I ntelligent T ransportation S ystems LBT Long Beach Transit LCV longer combination vehicle LDWS lane departure warning system L&I licensing and insurance ; a data set in MCMIS LNG liquefied natural gas LPG liquefied petroleum gas, propane, or autogas lpm liters per minute LRR low rolling resistance LTCCS Large Truck Crash Causation Study MAP - 21 Moving Ahead for Progress in the 21st Century Act (2012) MCMIS Motor Carrier Management Information System , a n FMCSA database MD/HDV medium - and heavy - duty vehicles MDV medium - duty vehicle mph miles per hour MSDS Material Safety Data Sheet MTBF mean time be tween failures MTBRC mean time between road calls MY model year (s) NACFE North American Council for Freight Efficiency NFPA National Fire Protection Association NGV natural gas vehiclex NHTSA National Highway Traffic Safety Administration NO x nitrogen o xides NREL National Renewable Energy Laboratory NTEA National Truck Equipment Association OEM original equipment manufacturer O&M operations and maintenance OOIDA Owner Operator Independent Driver Association PCIV plastics and composites intensive veh icles PHMSA Pipelines and Hazardous Materials Administration PM particulate matter PRD pressure relief device psi pounds per square inch PU power unit ; trucks or buses, excluding trailers RESS Rechargeable Energy Storage System R OI return on invest ment RSC roll stability control SAE Society of Automotive Engineers SBMTD Santa Barbara Municipal Transit District SCR selective catalytic reduction SME subject matter expert SMS Safety Measurement System; a process for assigning BASIC scores to carrie rs under the CSA initiative SOP standard operating procedure TARDEC United States Army Tank Automotive Research, Development And Engineering Center TPMS tire pressure maintenance system UMTRI University of Michigan Transportation Research Institute VMT vehicle miles traveled VRU vulnerable road user WMATA Washington Metropolitan Area Transit Authorityxi ACKNOWLEDGMENTS The principal authors of the report are Dr. Aviva Brecher, p rincipal t echnical a dvisor , and Dr. Alexander Epstein of the Energy Analys is and Sustainability Division in the Policy, Planning and Environment Technical Center at the USDOT Volpe National Transportation Systems Center , part of the Office of the Assistant Secretary for Research and Technology . Andrew Breck of the Organizational Performance Division contributed to Chapter 5 on regulatory analysis . The authors are also grateful for the valuable contributions and support from Volpe Energy and Sustainability Analysis Division colleagues , Scott Lian and Coralie Cooper , and Kevin Gree n, c hief of the Volpe CAF E Program Office . The authors thank the NHTSA Fuel Economy Division (NVS - 132) sponsors, James MacIsaac and J ames Tamm, c hief , for their guidance and feedback throughout the project, and Ken Katz , Lily Smith , and Ryan Hagen for thei r helpful reviews . We also acknowledge the Volpe Center editorial support team and our IAA officer Brunilda Santos.1 EXECUTIVE SUMMARY The 2010 National Research Council report Technologies and Approaches to Reducing the Fuel Consumption of Medium
- and He avy - Duty Vehicles evaluat ed technology options for improving the fuel efficiency (FE) of Class 2 - 8 medium and h eavy - d uty vehicles and recommended that NHTSA perform a thorough safety analysis to identify and evaluate potential safety issues . In 2011, NHTSA and EPA issued joint rulemaking for fuel efficiency and Gre enhouse Gas (GHG) emissions of m odel year (MY) 2014 - 2018 MD/HDVs. This report summarizes research and analysis findings on potential safety issues associated with both the diverse alternative fue ls (natural gas - CNG and LNG, propane, biodiesel , and power train electrification), and the specific FE technologies recently adopted by the MD/HDV fleets . These include Intelligent Transportation Systems (ITS) and telematics, speed limiters, idle reduction devices, tire technologies (single - wide tires, and tire pressure monitoring systems TPMS and automated tire inflation systems - ATIS), aerodynamic components, vehicle light weighting materials, and long combination vehicles (LCVs). Chapter 1 provid es an ove rview of the study rationale, background , and key objective , namely to identify the technical and operational/behavioral safety benefits and disbenefits of MD/HDVs equipped with FE technologies and using emerging alternative fuels. Recent MD/HDV national f leet crash safety statistical averages are also provided for context , although no information exists in crash reports relating to specific vehicle FE technologies and fuels . Chapters 2 and 3 are organized by clusters of functionally - related FE technologies (e.g., tire systems, ITS, light weighting materials, and aerodynamic systems) and alternative fuels, which are described and their respective associated potential safety issues are discussed . Chapter 2 summarizes the findings from a comprehensive review of available technical and trade literature and Internet sources regarding the benefits, potential safety hazards, and the applicable safety regulations and standards for deployed FE technologies and alternative fuels . C hapter 2 safety - relevant fuel - specif ic findings include: • Both CNG - and LNG - powered vehicles present potential hazards, and call for well known engineering and process controls to assure safe operability and crashworthiness . However, based on the reported incident rates of NGVs and the experi ences of adopting fleets, it appears that NGVs can be operated at least as safely as diesel MD/HDVs . Using natural gas instead of diesel fuel helps fleets comply with the MD/HD greenhouse gas rules that require up to 20 percent emissions reduction by 2018 . • There are no safety contraindications to the large scale fleet adoption of CNG or LNG fueled h eavy - d uty trucks and buses, and there is ample experience with the safe operation of large public transit fleets . Voluntary industry standards and best practice s suffice for safety assurance, though improved training of CMV operators and maintenance staff in natural gas safety of equipment and operating procedures is needed. • Observing CNG and LNG fuel system and maintenance facility standards , coupled with s ound design, manufacture and inspection of natural gas storage tanks will further reduce the potential for leaks, tank ruptures, fires, and explosions.2 • Biodiesel blends used as drop - in fuels have presented some operational safety concerns dependent on blending fraction, such as material compatibility, bio - fouling sludge accumulation, or cold - weather gelling . However, best practices for biodiesel storage, and improved gaskets and seals that are biodiesel resistant, combined with regular maintenance and leak inspe ction schedule for the fuel lines and components enable the safe use of biodiesel in newer MD/HDVs. • Propane (LPG, or autogas) presents well - known hazards including ignition (due to leaks or crash) that are preventable by using overfill prevention devices ( OPD s ) , which supplement the automatic stop - fill system on the fueling station side, and pressure release devices (PRD s ). Established best practices and safety codes (e.g. , NFPA) have proven that propane fueled MD/HDVs can be as operationally safe as the co nventionally - fueled counterparts . • As the market penetration of hybrid and electric drivetrain accelerates, and as the capacity and reliability of lithium ion batteries used in Rechargeable Energy Storage Systems (RESS) improve, associated potential safety hazards (e.g., electrocution from stranded energy, thermal runaway leading to battery fire) have become well understood, preventable and manageable. Existing and emerging industry technical and safety voluntary standards, applicable NHTSA regulations and guidance , and the growing experience with the operation of hybrid and electric MD/HDVs will enable the safe operation and large - scale adoption of safer and more efficient power - train electrification technologies . The safety findings from literature review pertaining to the specific FE technologies implemented to date in the MD/HDV fleet include: • Telematics

— integrating on - board sensors, video , and audio alerts for MD/HDV drivers

— offer potential improvements in both driver safety performance and fuel efficie ncy . Both camera and non - camera based telematics setups are currently integrated with available crash avoidance systems (such as ESC, RSC, LDWS, etc.) and appear to be well accepted by MD/HDV fleet drivers . • Both experience abroad and the cited U.S. studie s of trucks equipped with active speed limiters indicated a safety benefit, as measured by up to 50 percent reduced crash rates , in addition to fuel savings and other benefits, with good CMV driver acceptance. Any negative aspects were small and avoidable if all the speed limitation devices were set to the same speed, so there would be less need for overtaking at highway speeds. • No literature reports of adverse safety impacts were found regarding implementation of on - board idle - reduction technologies in MD/ HDVs (such as automatic start - stop, direct fired heaters, and APUs). • There was no clear consensus from the literature regarding the relative crash rates and highway safety impacts of LCVs, due to lack of sufficient data and controls and inconsistent study methodologies. Recent safety evaluations of LCVs and ongoing MAP 21 mandated studies will clarify and quantify this issue. • Tire technologies for FE (including ATIS, TPMS, LRR and single - wide tires) literature raised potential safety concerns regarding lowe r stability or loss of control, e.g . , when tire pressure is uneven or a single wide tire blows out on the highway. However, systems3 such as automated tire monitoring systems and stability enhancing electronic systems (ABS, ESC, RSC) may compensate and miti gate any adverse safety impacts. • Aerodynamic technologies that offer significant fuel savings have raised potential concerns about vehicle damage or injury in case of detached fairings or skirts, alt hough there were no documented incidents of this type in the literature . • Some light weighting materials may pose some fire safety and crashworthiness hazards , depending on their performance in structural or other vehicle subsystem applications (chassis, power - train, crash box or safety cage). Some composites ( fiberglass, plastics, CFRC, foams) may become brittle on impact or due to weathering from UV exposure or extreme cold. Industry has developed advanced, high performance lightweight material options tailored to their automotive application s , e.g., thermopla stics resistant to UV and weathering. No examples of such lightweight material failures on MD/HDVs were identified in the literature. Chapter 3 provides complementary inputs on the potential safety issues associated with FE technologies and alternative fu els obtained from Subject Matter Experts (SMEs) . The broad cross - section of SMEs consulted ha d experience with the operati o n of “green” truck and bus fleets, were F ederal program managers, or were industry developers of FE systems for MD/HDVs . S afety conce rns raised by the SMEs can be prevented or mitigated by complying with applicable regulations and safety standards and best practices, and are being addressed by evolving technologies, such as electronic collision prevention devices . Although SMEs raised s ome safety concerns, their experience indicates that system - or fuel - specific hazards can be prevented or mitigated by observing applicable industry standards, and by training managers, operators and maintenance staff in safety best practices. Specific saf ety concerns rais ed by SMEs based on their experience included: • Alternative fuels did not raise major safety concerns, but generally required better education and training of staff and operators. There was a concern expressed regarding high pressure (4 , 000 psi) CNG cylinders that could potentia lly explode in a crash scenario or if otherwise ruptured . However, aging CNG fuel tank safety can be assured by enforcing regulations such as FMVSS 304, and by periodic inspection and end - of - life disposal and replacem ent. A propane truck fleet manager found the fuel to be as safe as or safer than gasoline, and reported no safety issues with the company’s propane, nor with hybrid gasoline - electric trucks . OEMs of drivetrain hybridization and electrification systems, inc luding advanced Lithium Ion batteries for RESS, indicated that they undergo multiple safety tests and are designed with fail - safes for various misuse and abuse scenarios . Integration of hybrid components downstream by bodybuilders in retrofits, as opposed to new vehicles was deemed a potential safety risk. Another potential safety concern raised was the uncertain battery lifetime due to variability of climate, and duty cycles and aging. Without state - of - charge indicators, this could conceivably leave vehicl es underpowered or s tranded if the battery degrades and is not serviced or replaced in a timely manner . • ITS and telematics raised no safety concerns; on the contrary, fleet managers stated that “efficient drivers are safer drivers.” Monitoring and recordi ng of driver behavior, combined with coaching, appeared to reduce distracted and aggressive driving and provided significant FE and safety benefits .4 • A w ide - base single tire safety concern was the decrease in tire redundancy in case of a ti re blowout at hi ghway speeds . For LRR s , a concern was that they could negatively affect truck stopping distance and stability control. • A s peed - limiter safety concern was related to scenarios when such trucks pass other vehicles on the highway instead of staying in the rig ht - hand lane behind other vehicles . By combining speed limiters with driver training programs , overall truck safety could actually improve , as shown by international practice . • Aerodynamic systems safety performance to date was s atisfactory , with no instan ces of on - road detaching . However, covering underside or other components with aerodynamic fairings can make them harder to inspect, such as worn lugs, CNG relief valve shrouds, wheel covers, and certain fairings . Drivers and inspectors need to be able to see through wheel covers and to be able to access lug nuts through them. These covers must also be durable to withstand frequent road abuse . • For lightweighting materials, the safety concern raised was lower crashworthiness (debonding or brittle fracture o n impact) and the potential for decreased survivability in vehicle fires depending on the specific material choice and its application . The key finding from the literature review and SME interviews is that there are no major safety hazards preventing the adoption of FE technologies or the increased use of alternative fuels and vehicle electrification. In view of the sca rcity of hard data currently available on actual highway crashes that can be directly or causally attributed to adoption of FE technologie s and/or alternative fuels by MD/HDVs , and the limited experience with commercial truck and transit bus fleets oper at ions equipped with these technologies , it was not possible to perform a quantitative , probabilistic risk assessment, or even a semi - quantit ative preliminary hazard analysis (PHA). Thus, Chapter 4 employs a deterministic scenario - based hazard analysis of potential crash or other safety concerns identified from the literature review or raised by subject matter experts (SMEs) interviewed (e.g., interfaces with charging or refueling infrastructure) . For each specific hazard scenario discussed, the recommended prevention or mitigation options, including compliance with applicable NHTSA or FMCSA regulations, and voluntary industry standards and best practices are identified , along with FE technology or fuel - specific operator training . SMEs safety concerns identified in Sec 3.3 were complemented with actual incidents, and developed into the hazard scenarios analyzed in Chapter 4 . The scenario - based de terministic hazard analysis reflected not only the literature findings and SME’s safety concerns, but also real truck or bus mishaps that have occurred in the past. Key hazard analysis scena rios included: CNG - fueled truck and bus v ehicle f ires or e xplosion s d ue to t ank rupture, when pressurized fuel tanks were degraded due to aging or when PRDs failed; LNG truck crashes leading to fires, or LNG refueling - related mishaps; the flammability or brittle fracture issues related to lightweighting materials in cras hes; reduced safety performance for either LRR or wide - base tires; highway pile - ups when LCVs attempt to pass at highways speeds; aerodynamic components detaching while the vehicle traveled on a busy highway or urban roadway; and fires resulting in overhea ted lithium ion batteries in electric or hybrid buses. T hese hypothetical worst case scenarios appear to be preventable or can be mitigated by observing safety regulations and voluntary standards, or with engineering and operational best practices. Chapte r 5 reviews and discusses the existing Federal and State regulatory framework for safely operating MD/HDVs equipped with FE technologies or powered by alternative fuels . The review5 identif ies potential regulatory barriers to their large - scale deployment in the national fleet that could delay achievement of desired fuel consumption and environmental benefits , while ensuring equal or better safety performance . Chapter 6 summarizes the major findings and recommendations of this preliminary safety analysis of f uel efficiency technologies and alternative fuels adopted by MD/HDVs . Th e scenario - based hazard analysis, bas ed on the literature review and experts ’ inputs, indicates that MD/HDVs equipped with advanced FE technologies and/or using alternative fuels have manageable potentially adverse safety impacts. However, an in depth comparative statistical analysis of truck and bus crash databases over a longer time period ( at least five years ) is needed to understand quantitatively the safety implications of the rapi d adoption of ”green” technologies and fuels in the Nation ’s h eavy - d uty fleet.6 1 INTRODUCTION : BACKGROUND AND OBJ ECTIVES 1.1 Safety Performance of the National Medium Duty/H eavy - D uty Vehicle F leet and Technical Approach The adoption and deployment of new fuel - efficiency (FE) - improving technologies is accelerating across Class 2b - 8 MD/HDV s ( Figure 1 - 1 ) . Manufacturers , commercial truck and bus, and public transit bus fleets are implementing a diverse mix of FE technologies and alternativ e fuels so as to improve fuel efficiency in order to compl y with Phase I of the NHTSA and EPA fuel efficiency and GHG emissions regulations for mod e l years 2014 - 2018 . 1

Figure 1 - 1 : Medium and H eavy - D uty Ve hicles Type s by Gross Vehicle Weight Rating (GVWR) . 2

1 See posted Sept 15, 2011 NHTSA and EPA final rule at CFR Volume 76, Number 179, Pages 57105 - 57513, www.gpo.gov/fdsys/pkg/FR - 2011 - 09 - 15/html/2011 - 20740.htm 2 Figure 1 - 1a from EPA/NHTSA Final Rulemaking to Establish Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Me dium - and Heavy - Duty Engines and Vehicles Regulatory Impact Analysis7 In 2010 - 2011, the baseline years of NHTSA/EPA rulemaking , heavy - duty vehicle s represented only 4 percent of the national fleet, but consumed 20 percent of transportation fuel, and produced a similar fra ction of GHG emissions as shown below in Figure 1 - 2 3

.

Figure 1 - 2 : Heavy - duty vehicles share of national fleet, fuel consumption and GHG emissions According to the DOT/BTS Nation al Transportation Statistics 4 , in 2011 the h eavy - d uty fleet consisted of over 10 million trucks, more than 666 ,000 commercial buses, and about 63,00 0 transit buses . According to the APTA2011 Public Transportation Factbook 5 over 35 percent o f public transit buses used alternative power, including hybrid, electric, CNG, LNG and biodiesel blends. A 2010 National Research Council report examined the technology options to improve fuel efficiency for all eight classes of MD/HD vehicles, covering a broad range of functions and duty cycles. 6 The report evaluated and ranked the FE technologies , also described in Chapter 2 of this report , by their potential fuel savings and associated emission s reduction for vehicle classes ( Figure 1 - 3 ) . It examined the costs and benefits of hybrid power trains (hydraulic, parallel, or series electric), advanced lithium - ion battery packs, power management electronics and software, hydrogen fuel cell auxiliary power units (APUs) used to extend range, electric motors, regenerative braking, idle reduction and automated start - stop, lightweight materials, fairings for improved aerodynamics, and single wide tires . The report also noted, but did not discuss in detail, the potential for safety impacts of these fuel ef ficiency - improving technologies for MD/HD vehicles when deployed either singly or in synergistic clusters . The fuel efficiency -

3 Figure 1 - 1b source is the Feb. 2014 White House report: “Improving the Fuel Efficiency of American Trucks,” at www.whitehouse.gov/sites/default/files/docs/finaltrucksreport.pdf 4 See NTS Table 1 - 11 for 2010 and 2011 number of trucks and commercial and transit buses at www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/national_transportation_statistics/html/table_01_11.htm l 5 See www.apta.com/resources/statistics/Documents/FactBook/APTA_2011_Fact_Book.pdf 6 See March 2010 NRC report “Technologies and Approaches to Reducing the Fuel Consumption of MDHD Vehicles.”8 improving technologies considered in the NRC report include EPA SmartWay tractor trailer technologies. 7 The report also provided the technical underpinning for the 2011 medium - and heavy - duty regulation, and recommended that the agencies conduct a thorough evaluation of safety impacts associated with MD/HD efficiency technologies . Finding 6 - 15 of the NRC report stated that:

“ There are potential safety issues associated with particular fuel reduction technologies. Examples are hybrids that use high
- voltage batteries, or aerodynamic fairings that may detach from trucks on the road. ”

Figure 1 - 3 : R elative p otential fuel savings from six FE technolog i es applied to: t ractor - trailer s (TT), Class 3 - 6 box and bucket vehicles, t ransit buses and motor coaches; Class 8 - refuse trucks; and Class 2b pickups and vans. 8 A n in - depth safety analysis of fuel efficiency - improving technologies for MD/HDV fleet - wide deployment can help inform future FE rulemaking for the medium - and heavy - duty fleet . In addition , it may help to identify and address potential gaps in safety regulations and standards , and e nable the identification and prioritization of safety - focused research , while promoting fuel economy for environmental and economic benefits . The present study implements the NRC recommendation.

7 See www.epa.gov/smartway/transport/what - smartway/verified - technologies.htm and www.epa.gov/smartway/technolo gy/designated - tractors - trailers.htm 8 Ibid.9 The technical approach was t o organize the literature review so as to facilitate a focused analysis of potential FE technology and alternative fuel safety impacts , and compile t opi cally organized bibliographies e xtracted from an Excel database. This process facilitated the identification and analysis of potential sa fety issues related to specific FE technologies and alternative fuels adopted by vehicle fleets, and shed light on potential operator training and human factors safety issues . Over 500 references were reviewed and organized by topic (FE technology, alterna tive fuel, MD/HDV fleet employment and experience, regulations, safety, operational and human factors issues, etc.) . The references were organized in a sortable Excel database, and are both footnoted and listed in Appendices 7. 1 - 7. 6 as topical Bibliographi es: Safety; Fuel Efficiency Technology; Advanced Fuels; Operations/Human Factors; Regulatory Barriers ; and Green Vehicle Deployment . R elevant safety findings from the literature review are summarized in Chapter 2, and were complemented with inputs from foc used interviews with a representative and diverse set of Subject Matter Experts ( SMEs ) with fleet management or engineering experience in the use of F E technologie s and alternative fuels, as discussed in Chapter 3. Safety issues identified from Chapter s 2 and 3 were then developed into the deterministic hazard scenarios described and analyzed in Chapter 4, including respective prevention and mitigation options . Chapter 5 then focused on the Federal and State regulatory framework affecting MD/HDV adoption of FEs and alternative fuels, with the goal of identifying residual regulatory barriers. The key safety finding from this comprehensive review and analysis is that there are no major safety hazards preventing the adoption of FE technologies, n or from increas ed use of alternative fuels and vehicle electrification. Any identified safety concerns can be prevented or mitigated by complying with applicable regulations and safe ty standards and best practices and are being addressed by evolving technologies, such as electronic collision prevention devices . 1.2 National H eavy - D uty Fleet Crash Statistics and Trends Approximately 5.7 million commercial motor vehicle (CMV) drivers were licensed in 2010. The FMCSA CMV fleet and crash statistics 9 show that in 2010 the nationa l fleet was operated by 498,144 interstate freight carriers and included 846,051 buses operated by 11,701 interstate passenger carriers . In addition, public transit authorities operated over 63,000 buses in 2010. The public bus transit fleet used about 35 percent alternative power in 2010 and offered valuable experience with their safe operability. As illustrated below, the total number of alternative - fueled h eavy - d uty vehicles in the Nation ’s fleet in 2010 was under 70,000 - - a very small fraction of the c onventional fleet . Crash fatalities and injury totals and rates for trucks and buses , and other relevant safety performance annual statistics and trends are analyzed and reported annually by FMCSA and NHTSA , using data collected from States and analyzed b y NHTSA’s National Center for Statistics and Analysis (NCSA). Crash data provides safety performance trends over time in comparison with the Nation ’s entire vehicle fleet . The NCSA annual summaries , 10 and the 9 See Commercial Motor Vehicle Facts (March 2013) at www.fmcsa.dot.gov/safety/data - and - s tatistics/commercial motor - vehicle - facts - %E2%80%93 - march - 2013 10 See NCSA Large Trucks 2012 data at www - nrd.nhtsa.dot.gov/Pubs/811868.pdf10 FMCSA Motor Carrier Safety P rogress Reports 11 (MC SPR) offer fleet - wide safety statistics that provide a useful context for examining the relative safety performance of the small fraction of “green fleets” of MD/HDVs so equipped. Filed field crash reports and analyses to date have not included any informa tion on whether specific fuel efficiency technologies, or alternative fuels were involved as causal crash factors. The NHTSA Fatality Analysis Reporting System ( FARS ) contains only records of fatal crashes and does not include census data for motor carrier s. The FMCSA’s MCMIS includes records of all crashes involving interstate and intrastate hazmat motor carriers, both fatal and non - fatal . Another difference is that the FMCSA Motor Carrier Management Information System (MCMIS) the Crash Rate is defined as to the Crash Count/Power Unit (PU) 12 Count * 1000, whereas in the FARS the fatality rate is defined as the number of fatalities normalized to 100 million vehicle miles travelled (VMT). Crash figures and trends summarized by FMCSA 13 indicate a long term safet y improvement trend : the total number of large trucks involved in fatal crashes decreased over a decade by 25 percent , and by 30 percent for crash injuries. Similarly, the number of buses involved in fatal crashes decreased by 16 percent . However, the rat e of large truck and bus fatalities per 100 million VMT actually increased by 2 percent from 2010 to 2011. Since the NHTSA/EPA MD/HDV fuel efficiency regulations have used 2010 - 11 as the regulatory fuel efficiency baseline years, this safety analysis also focused on crash safety performance data for the same period. Table 1 - 1 shows the 2009 - 2011 FMCSA number of truck crashes, fatalities and injuries. In 2009, NHTSA reported 3,380 fatalities from large truck crashes and only 254 from bus crashes, with 93,00 0 injured from both truck and bus crashes. Overall, the HDV fleet VMT in 2011 decreased from 2,966,506 million to 2,930,654 million compared to 2010, a decrease of 1.2 percent . Large truck crash fatalities and injuries, and the respective rates per 100 M V MT in 2010 and 2011 14 were compared to the national overall fleet rates: while the overall fleet fatality rate for the entire fleet fell to a historic low of 1.10 in 2011, the injury rate increased by 1.3 percent from 2010 to 2011. For large truck crashes h owever 15 , there was a 1.9 percent increase in the number of people killed (from 3.686 in 2010 to 3,757 in 2011), with the corresponding fatality rate increase from 1.22 to 1.35. Although there has been an increase in fatalities from large truck crashes fro m 2009 to 2011, large trucks continue to have a better relative safety record than the light - duty fleet: Total fatalities from large truck crashes rose from 3,380 in 2009 to 3,686 in 2010 (+9%), and 3,757 (+2%) in 2011. But the 2009 fatality rate for large trucks and buses was only 0.123 per 100 million VMT, compared to 1.14 for the entire fleet, including cars and light trucks . Similarly, the crash injury rate in 2009 for large trucks and buses was 3.15 per 100 million VMT, compared to 75.1 for the entire U . S . fleet. This superior CMV safety performance relative to privately owned light duty

11 See www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/MCSPR - 09 - 30 - 13.pdf 12 A power unit (PU) as defined by FMCSA is a truck or a bus, excluding trailers. 13 See FMCSA “ Large Truck and Bus Crash Facts 2011 at www.fmcsa.dot.gov/safety/research - and - analysis/large truck - and - bus - crash - facts - 2011 14 2011 Motor vehicle crashes - an overview at www - nrd.nhtsa.dot.gov/Pubs/811701.pdf 15 See NHTSA Traffic Safety Facts 2011 Data - Large Trucks at www - nrd.nhtsa.dot.gov/Pubs/811752.pdf11 vehicles may be due to well - trained professional CMV drivers, and to frequently inspected and well - maintained vehicles. In 2010, there were 3,341 fatalities and 56,000 injuries from large truck crashes (an increase of about 9 % relative to the 2009); and 247 fatalities and 12,000 injuries for buses. The se 2010 NHTSA large truck crash statistics 16 (see also Table 1 - 1 ) show that, fo r the 10,770,054 large trucks registered and the ir risk exposure from 286,585 million VMTs, the large truck crash vehicle involvement rate was: • 1.22 for 3,484 large trucks fatal crashes ; and • 20 for 58,000 trucks involved in injury crashes . An updated FMCS A 17 analysis also summarized and compared 2009 through 2011 large truck crash totals and rates normalized to 100 million VMT. Although truck crash fatalities ( Table 1 - 2 ) totals increased from 3,686 in 2010 to 3,757 in 2011 (by 1.9%) and so did injuries (by 15%), the associated fatality rate decreased modestly by 0.9 percent , while the injury rate increased by 1.3 percent . Large truck crashes resulted in 23,000 injuries in 2011, versus 20,000 in 2010, or a 15 percent increase. From 2011 to 2012, the number of large trucks involved in fatal crashes again increased by 5 percent , and the fatality rate per 100 million VMT increased by 4 percent . 18 Table 1 - 1 : FMCSA S afety S tatis tics 2009 - 2011. 19

16 See Table 36 in NHTSA “2010 Motor Vehicle Crash Data from FARS and GES” at www nrd.nhtsa.dot.gov/Pubs/811659.pdf 17 See “ Commercial Motor Vehicle (CMV) Facts - March 2013” at www.fmcsa.dot.gov/safety/data - and statistics/commercial - motor - vehicle - facts - %E2%80%93 - march - 2013 18 See www.fmcsa.dot.gov/safety/data - and - statistics/large - truck - and - bus - crash - facts - 2012 19 See March 2012 Motor Carrier Safety Progress Report (MCSPR) at http://ebookbrowse.com/mcspr - 03 - 31 - 12 - pdf - d38981359412 Table 1 - 2 : Truck Fatalities in 2010 - 11

This report focuses on the relative safety performance of the currently very small fraction of h eavy - d uty vehicles in the fleet that have adopted fuel efficiency technologies, or alternative fuels (CNG, LPG, biodiesel, hybrid - electric and electric) . In attempting to link FE technologies and driver training to the safety of advanced vehicles relative to the overall fleet, it is important to examine the causes contributing to large trucks crashes. Table 1 - 3 summarizes the findings from the 2007 FMCSA Large Trucks Crash Causation Study (LTCCS). Causative factor analysis showed that over 90 percent of crashes ar e due to human factors, such as driver distraction or error, highlighting the importance of driver fitness and training . Only 10 percent of crashes we re vehicle - related , so any safety incidents attributable to FE technologies and/or alternative fuels would be included in this category. Table 1 - 3 : Estimated Numbers of Trucks in All Crashes, by Critical Reasons 20 Critical Reasons Number of Trucks Percent of Total Driver 68,000 87%

Non - Performance 9,000 12% Recognition 22,000 28% Decision 30,000 38% Performance 7,000 9% Vehicle 8,000 10% Environment 2,000 3% Total Number of Large Trucks Coded with Critical Reason 78,000 100% Total Number of Large Trucks Not Coded with Critical Reason 63,000

— Total Number of Large Trucks Involved in Crashes 141,000

—

20 See Analysis Brief of FMCSA Large Truck Crash Causation Study (2007) at www.fmcsa.dot.gov/fa cts research/research - technology/analysis/FMCSA - RRA - 07 - 017.htm ; LTCCS Table Notes : Results shown are national estimates for the 141,000 large trucks estimated to have been involved in fatal and injury crashes during the study period. The estimates may dif fer from true values, because they are based on a probability sample of crashes and not a census of all crashes. Estimates are rounded to the nearest 1,000 large trucks.13 The total number of alternatively - fueled trucks and buses in the U.S. fleet, and their current fuel consumption and fuel efficiency were extracted from annual Department of Energy (DOE) publica tions . 21 Table 1 - 4 and Table 1 - 5 provide Energy Information Administration (EIA) statistics 22 on the number of MD/HD Alternative Fuel Vehicles (AFVs) in use for 2010 and 2011 , respectively, by fuel type and weight class. Table 1 - 4 : Alternative - Fuel Vehicles in Use by Fleet Operators : 2010 23 Light Duty Medium Duty Heavy Duty Total Ethanol

— Flex Fuel 592,231 26,255 18 618,504 Nat ural Gas

— Total 67,296 22,575 28,976 118,847 Compressed Natural Gas 67,296 22,521 26,000 115,817 Liquefied Natural Gas 0 54 2,976 3,030 LPG

— Propane 76,694 27,771 36,057 140,522 Electric

— Battery 56,566 86 779 57,451 Total 792,787 76,687 65,850 935 ,324 Table 1 - 5 : A lternative - Fuel Vehicles in Use 2011 by Weight Class and Fuel Type 24 Light Duty Medium Duty Heavy Duty Total Ethanol

— Flex Fuel 819,133 43,387 317 862,837 Liquid Petroleum Gas (Propane) 76,647 26,855 35,975 139,477 Natural Gas 66,147 23,473 32,030 121,650 Compressed Natural Gas 65,980 23,343 28,891 118,214 Liquefied Natural Gas 167 130 3,139 3,436 Electric

— Battery 66,409 87 779 67,295 Hydrogen 425 1 101 527 Total 1,028,761 93, 803 69,222 1,191,786

21 Current Annual Transportation Energy Data Book posted at www.cta.ornl.gov/data 22 See Alternatives to Traditional Transportation Fuels 2010 Report Table at www.eia.gov/tools/faqs/faq.cfm?id=93&t=4 23 See www.eia.gov/renewable/afv/index.cfm 24 See Alternatives to Traditional Transportation Fuels 2011 report at www.eia.gov/renewable/afv/index.cfm14 An APTA study found that as of January 2011 over 35 percent of public transit buses used alternative fuels (such as CNG or hybrid electric technology), and the adoption rate of fuel efficiency technologies has been accelerating. 25 Rece nt DOE data 26 on MD/HDVs show that trucks consumed 2,901,000 barrels per day or 21.4 percent of total transportation fuel use, while buses consumed 95.0 bblpd, representing only 0.7 percent of total transportation fuel use . The Class 8 trucks had the highes t annual fuel use of about 13,000 GGE/year, followed by transit buses with 10,800 GGE/year, and refuse trucks with 10,000 GGE/year. The total for delivery trucks and school buses combined was 2,000 GGE/year. The DOE number of MD/HDVs by type, and fuel eff iciency include d : • 8,356 registered single unit trucks with an average FE of 7.4 mpg ; • 2,617 combination trucks with average FE of 6 mpg ; and • 850,000 buses in the United States , of which 650,000 are school buses and the rest are intercity buses and 65,363 t ransit buses averaging 7.1 mpg. 27 The DOE Alternative Fuels Data Center (AFDC) case studies and the “Clean Cities Guide to Alternative Fuel and Advanced Medium and H eavy - D uty Vehicles 28 ”discuss truck and bus fleets that successfully converted to, or adopted alternative fuels (CNG, LNG, biofuels) or hybrid electric propulsion. 29 The DOE National Clean Fleets Partnership enlisted 28 of the largest corporate commercial fleet owners/operators , that successfully adopted FE technologies and/or alternative fuels , as discussed in a safety context in Sections 2 and 3. 30 The rate of adoption over time for various FE technologies by truck fleets was studied by NACFE in annual benchmark reports 31 focused primarily on cost recovery through fuel savings and operational effi ciency gains, along with barriers to increased fleet penetration, but did not address potential safety issues. 32 NACFE annual surveys of “green” freight truck fleet managers were focused only on benchmarking large fleets adoption rates of, and payback time for FE technologies. NACFE adoption trends reported for specific FE technologies are also shown in Figure 2 - 12 and further discussed in Chapter 2. Similarly, CalHEAT, the California truck research center, conducted recent surveys of truck fleets regarding the market barriers to adoption of FE technologies and alternative fuels, 33 again without addressing any associated potential safety concerns . Literature resources reviewed and findings on potential safety issues

25 See www.apta.com/mediacenter/pressreleases/2013/Pages/130422_Earth - D ay.aspx 26 Posted DOE AFV data at: www.afdc.energy.gov/data/tab/all/data_set/10308 27 See BTS table www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/national_transportation_statistics/html/table_04_15.htm l 28 See www.afdc.energy.gov/uploads/publication/medium_heavy_duty_guide.pdf 29 See www.afdc.energy.gov/case 30 See www.afdc.e nergy.gov/uploads/publication/60619.pdf 31 See NACFE - ICCT 2013 report at www.theicct.org/sites/default/files/publications/ICCT - NACFE C SS_Barriers_Report_Final_20130722.pdf 32 See http://nacfe.org/ postings 33 See CalHEAT “Market Barriers And Opportunities For Alternative Fuel - Hybrid Systems” June 2013 at www.calstart.org/Libraries/CalHEAT_2013_Documents_Presentations/CalHEAT_Market_Barriers_and_Opportunit ies_for_Alternative_Fuel - Hybri d_Systems.sflb.ashx15 associated with MD/HDV fleet adoption of FE technologies and alt - fuels are discussed below in Chapter 2. In conclusion, although the national h eavy - d uty motor vehicles crash statistics for 2010 - 2011 provide a verage baseline for fleet safety performance, these statistics could not be used for a saf ety analysis of specific FE technologies due to the lack of such information in crash field reports, and due to the very small number of such vehicles compared to the conventional MD/HDV fleet. A preliminary analysis of large trucks and bus crashes in 20 10 - 2011 was conducted as part of this study to compare crash rates of conventional CMVs to the few FE

– equipped “green” fleets. However, the small percentage of hybrid, electric, and a lternative - fuels vehicles in the overall fleet resulted in an analysis t hat would rely on the statistics of small numbers. Therefore, comparisons between the crash rates of conventional fleets and green fleets was deemed inadvisable . Analysis over a longer time period, or after a larger penetration of FE technologies and/or al ternative fuels occurs in the MD/HDV fleet, may allow for statistically meaningful comparisons.16 2 REVIEW OF LITERATURE ON ADOPTION OF FE TE CHNOLOGY CLUSTERS, ALTERNATIVE FUELS, A ND OPERATIONAL SAFET Y OF MD/HDV FLEETS 2.1 Introduction A comprehensive literatur e survey was conducted to identify any MD/HDV safety issues regarding existing and emerging FE technologies and alternative fuels. Resources reviewed included research reports, technical articles , and news items posted on the Internet; conference proceedin gs and presentations; annual statistical data on truck and bus safety and energy consumption; Congressional hearings, and trade association surveys and testimonies, etc . The report focus was on extracting any MD/HDV safety information specific to the NHTSA and EPA - approved FE technologies from key sources (e.g., EPA SmartWay, DOE Advanced Vehicle Technologies - AVT and 21st Century Truck, DOD/TARDEC, CALSTART, and NRC FE technology reports); crash safety from IIHS, NHTSA, and FMCSA MCMIS databases; FHWA repo rts on extra - heavy trucks and trailers; regulatory information from the NHTSA R&D and regulatory plan, commercial fleet truck and bus trade associations; Congressional testimony; newsletters, etc.). The bibliography database, comprising over 50 0 reference s, was organized as an Excel spreadsheet, which can be “filtered” by category to facilitate data mining and retrieval by topic (vehicle safety, FE technology, alt - fuels, operational b est p ractices, regulatory documents). Separate bibliographies were compil ed by topic, i.e., specific FE technology applied to MD/HDVs, safety statistics and analyses, alternative fuels, operational and behavioral issues, and green fleet vehicle deployment. (See Appendices 7.1 to 7.6 .) Sections 2.2 - 2.9 describe the literature fi ndings on MD/HDV safety issues, organized by the specific FE technology and/or alternative fuel wherever possible . References cited relating to MD/HDV fleet deployment of specific FE technologies and alternative fuels provide the general overview of their current adoption and penetration . However, most references offer little to no quantitative statistical data regarding potential hazards, and only sparse evidence regarding the safety impacts of individual FE technologies, alternative fuels, and related dri ver operation factors. 2.2 Adoption of Alternative Clean Fuels 2.2.1 Natural Gas Benefits and Safety Issues Natural gas is a domestically produced gaseous fuel readily available through the utility infrastructure. It is an odorless, nontoxic, gaseous mixture of hyd rocarbons

— predominantly methane (CH 4 ), which must be odorized for leaks to be detectable . At high concentrations it is a potential asphyxiant, as well as a fire or explosion hazard; methane is also a powerful Greenhouse Gas (GHG) . Because of the gaseous na ture of this fuel, it must be stored onboard a vehicle either as compressed natural gas (CNG) or liquefied natural gas (LNG). 34

34 DOE EERE. 2012d. National Clean Fleets Partnership www1.eere.energy.gov/cleancities/national_partnership.html17 CNG is used in light - , medium - , and heavy - duty applications . To provide adequate driving range, it is stored onboard a vehicle i n cylinders at a pressure of 3,000 to 5,000 pounds per square inch (psi). The AFDC states that a CNG - powered vehicle has approximately the same fuel economy as a conventional gasoline vehicle on a gasoline - gallon - equivalent (GGE) basis. 35 LNG is produced b y purifying natural gas and super - cooling it to - 260°F to turn it into a liquid. Because it must be kept at cold temperatures, LNG is stored in double - walled, vacuum - insulated pressure vessels at up to 230 psi. LNG is good for trucks needing a longer range because liquid is more dense than gas (CNG) and more energy can be stored by volume in a given tank. LNG is typically used in medium - and heavy - duty vehicles. A GGE equals about 1.5 gallons of LNG. Propane is another hydrocarbon alternative fuel (C 3 H 8 ) fu el sometimes referred to as liquefied petroleum gas (LPG) or autogas. It is produced domestically from both natural gas processing and crude oil refining. It is also nontoxic, colorless, and virtually odorless. As with natural gas, an identifying odor is a dded so the gas can be readily detected. 2.2.1.1 Penetration/Adoption CNG vehicles are currently more commonplace than LNG vehicles. Using CNG as fuel is currently best suited for vehicles that are housed and fueled at a common location, such as public transit veh icles, refuse trucks, and delivery fleets because of refueling infrastructure and special handling requirements. Modest growth of CNG fueling stations has been spurred by the Energy Policy Act of 1992, and demand is expected to rise further. 36 However, eve n though the United States has about 180,000 gasoline stations, there are only about 1,000 CNG stations, with only half open to the public. 37 Large vehicles are necessary to accommodate the cryogenic fuel tanks used to store LNG, which are 70 percent larg er by volume than a comparable diesel tank . (Compressed gas needs about six times as much space as diesel, even when squeezed down to 3,000 psi.) LNG systems are typically more expensive than CNG systems, as is the fuel itself, but LNG vehicles can exceed 300 miles before needing to be refueled, in contrast to CNG vehicles . Therefore, LNG is considered an alternative for both long - haul (thousands of miles) and short - haul (hundreds of mile) trucking . However, until LNG infrastructure is commonplace, it is u nlikely to become a widespread alternative fuel. 38

35 See Natural Gas Fuel Basics: 1 GGE equals about 5.66 po unds of CNG, at www.afdc.energy.gov/fuels/natural_gas_basics.html 36 Carbon War Room Research & Intelligenc e Group. 2012. Unlocking fuel - saving technologies in trucking and fleets http://carbonwa rroom.com/sites/default/files/reports/Unlocking%20Fuel%20Saving%20Technologies%20in%20Tru cking%20and%20Fleets%20(Carbon%20War%20Room).pdf 37 Garthwaite, J. 2011. Trading Oil for Natural Gas in the Truck Lane http://news.nationalgeographic.com/news/energy/2011/09/110902 - natural - gas - fuel - for - trucks 38 See Carbon War Room Research & Intelligence Group. 2012. Unlocking fuel - saving technologies in trucking and fleets http://carbonwarroom.com/sites/default/files/reports/Unlocking%20Fuel%20Saving%20Technologies%20in%20Tru cking%20and%20Fleets%20(Carbon%20War%20Room).pdf18 Even though natural gas has long been used to power vehicles, only about 0.1 percent of current U.S. natural gas production is currently used for transportation fuel. 39 According to NGV America, a trade a ssociation, the amount of diesel fuel currently used annually for highway travel is equivalent to six trillion cubic feet of natural gas. Current national natural gas demand is in the range of 22 trillion cubic feet a year, suggesting that the diesel use c ould in principle be displaced by natural gas . Compressed natural gas (CNG) consumption for transportation has increased steadily since 1995, as shown in Figure 2 - 1 . As discussed in Section 2.2.3, the use of propane, which was th e most common alternative vehicle fuel in the early 1990s, has trended downward as CNG (and to a lesser extent LNG) has become more popular.

Figure 2 - 1 : Estimated Consumption of Alternative Fuel by AFVs in the United States (Ref. 15) Natural gas vehicles have been in use in the United States since the early 1970s, especially by urban transit bus “clean” fleets, and, to a lower extent, by personal or fleet dual - fueled vehicles, i.e., vehicles that can operate on two different fuels. By 2010, there were 115,863 CNG and 3,354 LNG vehicles across all weight classes in the United States ( Figure 2 - 2 ), which amounts to less than one percent of the 15 million NGVs globally, the vast majority of which are light - duty vehicles. 40 , 41 A total of 43,088 commercial vehicles were using natural gas in 2010, of which approximately 35,000 were medium or heavy duty.

39 DOE/EERE 2012, A lternative Fuels and Advanced Vehicles Data Center (AFDC), www.afdc.energy.gov/afdc/fuels/natural_gas.html 40 Ibid. 0 50 100 150 200 250Million GGEs CNG Propane E85 LNG Electric Hydrogen E95 Methanol (M85) Methanol M100

www.afdc.energy.gov/afdc/data19 Figure 2 - 2 : Alternative Fueled Vehicles in Use in the United States 42 Adoption of natural gas in transit bus fleets increased rapidly in the late 1990s, growing from 2.8 percent of buses in 1996 to 18.6 percent in 2011 . More than 40 North American transit agencies now use buses powered by CNG. I n 2011, the Los Angeles County Metropolitan Transportation Authority became the first major U.S. transit agency with a fleet 100 percent equipped with alternative fuel technologies

 almost all CNG. 43 The 21,510 natural gas - powered transit buses comprise alm ost two - thirds of U.S. MD/HDV NGVs. 44 In heavy - duty vehicles, both dedicated natural gas and dual - fuel, compression - ignited engines are available . The dual - fuel engines are slightly more fuel - efficient than the spark ignited dedicated engines, but they als o increase the complexity of the fuel storage system by requiring storage of both types of fuel. 45

41 Carbon War Room Research & Intelligence Group. 2012. Unlocking fuel - saving technologies in trucking and fleets http://carbonwarroom.com/sites/default/files/reports/Unlocking%20Fuel%20Saving%20Technologies%20in%20Tru cking%20and%20Fleets%20(Carbon%20War%20Room).pdf 42 DOE EERE. 2012a. Alternative Fuels and Advanced Vehicles Data Center www.afdc.energy.gov/afdc/fuels/natural_gas.html 43 Gentry, W. 2012. Statement of William Gentry, President, Gentry Trailways and on behalf of American Bus Association and United Motorcoach Association Subcommit tee on Highways and Transit, House Transportation and infrastructure Committee, U.S. House of Representatives http://republicans.transportation.h ouse.gov/Media/file/TestimonyHighways/2012 - 09 - 13 - Gentry.pdf 44 Kwan, Q. 2012. Safety Considerations Related to Commercial Vehicles Using Natural Gas www1.eere.energy.gov/cleancities/pdfs/ngvtf12_kwan.pdf 45 DOE EERE. 2012a. Alternative Fuels and Advanced Ve hicles Data Center www.afdc.energy.gov/afdc/fuels/natural_gas.html 0 50 100 150 200 250 300 350 400Thousand Vehicles Electric
LNG CNG Propane20 LNG has not been widely deployed in transit systems to date, 46 although over 1,000 transit buses were operational in 2003 with seven public transit agencies o perating LNG powered buses. 47 According to the DOE Alternative Fuels and AFDC, there were 836 public and private CNG stations and 38 LNG stations in the United States as of June 2, 2010. Examples of significant adoption of natural gas by truck fleets incl ude those below: • United Parcel Service (UPS) operates about 1,100 vehicles running on LNG or compressed natural gas (CNG in its global fleet, including about 60 LNG heavy tractor trucks. 48 These new vehicles will reduce greenhouse gas emissions by 25 perce nt compared to the older generation diesel trucks they replaced . The original demonstration fleet of 11 vehicles shuttling between California and Las Vegas showed UPS that LNG trucks could handle demanding situations like hauling multiple trailers over mou ntain ranges. 49 Out of its 17,000 tractor - trailers, UPS would like to convert 1,000 to liquefied natural gas, depending on the availability of refueling infrastructure. UPS is also using propane, electric and hybrid electric vehicles to help the company re ach its 20 percent mpg improvement goal for the entire U.S. package delivery fleet between 2000 and 2020. 50 • Waste Management has over 1,000 LNG trucks in its fleet . A third of its California fleet is fueled by LNG derived from the decomposition of organic waste in the company’s Altamont Landfill in Livermore, C alifornia . Waste Management has CNG and LNG fueling stations at 17 of its facilities throughout North America with more under development. 51 Waste Management began operating a fleet of heavy - duty ref use trucks powered by LNG in Pennsylvania as early as 1997 . This implementation was considered successful, although the LNG trucks had a 9 percent to 12 percent lower fuel economy versus diesel. 52 • South Coast Air Quality Management District (SCAQMD) Heavy - Duty Natural Gas Drayage Truck Replacement Program in California purchased 219 LNG trucks in 2008,

46 Friedman, D. M., & Malcosky, N. D. 1996. Liquefied Natural G as Safety in Transit Operations: Final Report http://trid.trb.org/view.aspx?id=713273 47 See www.afdc.energy.gov/pdfs/mod04_lng.pdf and Gentry, W. 2012. Statement of William Gentry, President, Gentry Trailways and on behalf of American Bus Association and United Motorcoach Association Subcommittee on Highways and Transit, House Transportation and infrastructure Committee, U.S. House of Representative http://republicans.transportation.house.gov/Media/file/TestimonyHighways/2012 - 09 - 13 - Gentry.pdf 48 “UPS press release Feb.22, 2011 “UPS Clearing the air with n ew LNG tractors” at www.pressroom.ups.com 49 Wald, M. 2011. U.P.S. Finds a Substitute for Diesel: Natural Gas, at 260 Degrees Below Zero http://green.blogs.nytimes.com/2011/02/22/u - p - s - finds - a - substitute - for - diesel - natural - gas - at - 260 - degrees - below zero/ 50 Environmental Leader. 2011. UPS Adds to its Natural Gas Truck Fleet www.environmentalleader.com/2011/02/25/ups - adds - to - its - natural - gas - truck - fleet 51 Work Truck Mag azine. 2011. Waste Management Adds 1,000th Natural Gas Truck to Fleet www.worktruckonline.com/Channel/Fu el - Management/News/Story/2011/07/Waste - Management - Adds - 1 - 000th Natural - Gas - Truck - to - Fleet.aspx 52 Clark, K. C. P. N. N. 2001. Waste Management's LNG Truck Fleet Final Results www.afdc.energy.gov/pdfs/waste_lng_final.pdf stated: “This fuel economy result shows considerable improvement compared to other heavy - duty natural gas engine products.”21 all of which were scheduled to be deployed by the end of 2012 . These heavy - duty trucks completed 5.3 million LNG - powered miles by the end of 2011. 53 • Green Ene rgy Oilfield Services operates 60 LNG - powered vacuum and winch trucks supporting its gas drilling operations. 54 • AT&T’s fleet of 73,500 vehicles includes 3,000 NGVs, and by 2013, the company reportedly plans to increase the number of natural gas vehicles to 8,000. 55 According to a recent economic report, the widespread fleet adoption of LNG heavy - duty trucks still faces hurdles, including the scarcity of LNG retail outlets, refueling infrastructure stations, uncertainty over future governmental support, and th e need for new training and logistics . Further study in the areas of hardware maintenance, availability of replacement parts, and the long - term durability of cryogenic fuel tanks would enable better long - term assessments of potential safety effects . 56 2.2.1.2 Bene fits Natural gas vehicles (NGVs) have similar power, acceleration, and cruising speed to gasoline or diesel vehicles. The driving range of NGVs is generally lower than that of comparable gasoline and diesel vehicles because less energy content can be store d in a natural gas tank of the same size as that of gasoline or diesel fuels. Extra natural gas storage tanks, or the use of LNG instead of CNG, can increase the range for large vehicles. However, this imposes a fuel economy penalty due to the added weight and reduces the amount of useable space in a vehicle. 57 A bus with an LNG fuel system weighs approximately 1,000 pounds less than one with a CNG fuel system and has a longer range . One gallon of LNG contains about 60 percent of the energy in a gallon of d iesel fuel, while CNG at 3,600 pounds per square inch (psi) pressure contains only about 30 percent. Natural gas burns cleaner than gasoline or diesel, and it can help ensure compliance with the EPA Clean Air and the recent NHTSA/EPA MD/HDV fuel efficienc y and GHG emissions rules. Natural gas offers life cycle GHG emissions benefits over conventional fuels, as well as a reduction in EPA regulated tailpipe emissions. 58 Assessments of the greenhouse gas benefits of natural gas fuels vary, but they generally s how that on an energy basis (grams per million BTU or grams per megajoule) CNG has 15 - 20 percent

53 DOE EERE. 2012c. Largest U.S. Port Complex Embraces LNG for Heavy - Duty T rucks www.afdc.energy.gov/case/1203 54 Work Tru ck Magazine. 2012. Green Energy Oilfield Services Builds Green Truck Fleet www.worktruckonline.com/News/Story/2012/02/Green - Energ y - Oilfield - Services - Builds - Green - Truck - Fleet.aspx 55 Garthwaite, J. 2011. Trading Oil for Natural Gas in the Truck Lane http://news.nationalgeographic.com/news/energy/2011/09/110902 - natural - gas - fuel - for - trucks/ 56 Oil and Gas Journal. 2012. LNG seen via ble fuel for heavy - duty trucks www.ogj.com/articles/2012/06/lng - seen - viable - fuel - for - heavy - duty - trucks.html 57 Friedman, D. M., & Malcosky, N. D. 1996. Liquefied Natural Gas Safety in Transit Operations: Final Report http://trid.trb.org/view.aspx?id=713273 58 DOE EERE. 2012a. Alternative Fuels and Ad vanced Vehicles Data Center www.afdc.energy.gov/afdc/fuels/natural_gas.html22 lower GHG emissions than diesel fuel, while LNG has 3 - 9 percent lower GHG emissions. 59 The lower benefits from LNG are due to a higher energy requirement for l iquefaction of LNG compared to compression of CNG . However, natural gas engines typically have lower efficiency than diesel engines, so some of the GHG benefit of natural gas fuels is reduced in practice, i.e., per - mile GHG reductions from the use of natur al gas fuels instead of diesel will be lower due to greater fuel use per mile . In the future, these benefits may increase if natural gas supplies are blended with renewable natural gas captured from the natural decay of organic materials, e.g., in landfill s . This biomethane could reduce life cycle carbon emissions by 85 - 90 percent when compared with diesel and gasoline, as shown in Figure 2 - 3 . 60

Figure 2 - 3 : Carbon Intensity of Variou s Fuels in California HDVs. 61 2.2.1.3 Safety Considerations of CNG - Fueled MD/HDVs Since LNG and CNG tanker trucks are considered hazardous material transport, they are regulated by PHMSA and were not considered in this literature review . Only the crash rates of ve hicles propelled by natural gas were considered. Natural gas has certain safety advantages compared to gasoline and diesel: it is non - toxic, lighter than air, and dissipates rapidly when released. An odorant is added to provide a distinctive smell that is easy to recognize, and it is detectable at 20 percent of the lower flammability limit. 62 U nlike diesel and gasoline leaks, which puddle on the ground and can create an on - going hazard

59 Argonne National Laboratory Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET ) Model, https://greet.es.anl.gov/ 60 Natural Gas Vehicles for America. 2012. NGVs and the Environment www.ngvc.org/about_ngv/ngv_environ.html 61 DOE EERE. 2012a. Alternative Fuels and Advanced Vehicles Data Center www.afdc.energy.gov/afdc/fuels/natural_gas.html 62 Clean Vehicle Education Foundation. 2010. How Safe are Natural Gas Vehicles? www.cleanvehicle.org/committee/technical/PDFs/Web - TC - TechBul 2 - Safety.pdf 95 92 83 82 75 75

46 39

16 14 13

0 10 20 30 40 50 60 70 80 90 100

ULSD LNG Biodiesel (Soy) Renew. Diesel (Soy) CNG Hydrogen (NG) Electricity Renew. Diesel (Tallow) Biodiesel (Grease) Dairy CNG Landfill CNGCarbon Intensity (adjusted gCO2e/MJ)

www.afdc.energy.gov/afdc/data/23 over a wide area, leaking natural gas tends to rise and dissipate to non - hazardous levels quickly, with only a short, vertical column directly above the leak in which the gas mixture is flammable. Natural gas leaks therefore pose little fire or explosion risk if the gas is leaking into open air. However, if the leak is into an enclosed space (either a building or an enclosed space on the vehicle) the resulting fire and explosion hazard can be significant, depending on the size of the leak. While natural gas is non - toxic, it can displace the air in a pit, and/or reduce oxygen co ncentration levels, and potentially pose an asphyxiation hazard to workers. Hazards relating to CNG also include fire, thermal explosion if release is into an enclosed space, and mechanical rupture of pressure vessel. Gas release can occur from a fuel syst em leak or from activation of a PRD . Ignition can also result from contact with hot surfaces, open flames, and sparks, including static electricity . 63 There are four basic types of CNG tank designs: Type 1 - all steel, Type 2 - metal liner with hoop wrapped composite; Type 3 metal liner with fully wrapped composite; and Type 4 - plastic liner with fully wrapped composite (glass fiber or carbon fiber may be used) . Onboard CNG storage tank pressures range from 250 bars, 350 bars, to 700 bars, but all must have p ressure relief valves. At a CNG fueling station, the gas is compressed before being supplied to vehicles at 3,000 to 3,600 psi . This stored energy represents a potential hazard not found in unpressurized diesel or gasoline fuel tanks . CNG fuel tanks can r elease significant energy if the tank suddenly fails. Such failures are rare, but have occurred . According to one database, between 2000 and 2008 there were only 26 CNG cylinder failures worldwide, which is a very small dataset for predictive failure analy sis. 64 Figure 2 - 4 lists the causes of these failure incidents . The leading causes of catastrophic cylinder ruptures were vehicle fires and environmental damage, such as corrosion . Several ruptures occurred when exposure to a fire on board the vehicle failed to activate the cylinder Pressure Relief Devices (PRDs), and the cylinder pressure increased until explosion. Safety in the design and operation of the CNG refueling infrastructure is partly addressed by National Fire Protectio n Association (NFPA) Code 52, Vehicular Gas Systems Code, which requires minimum venting rates for indoor facilities as well as pressure relief devices on all storage systems that discharge to a sufficiently vented indoor or to an outdoor area . There is al so a recommended practice from the Society of Automotive Engineers, SAE J2406, Recommended Practices for CNG Powered Medium and Heavy
- Duty Trucks . Both of the above are voluntary. A 2005 probabilistic risk assessment study of CNG bus safety 65 concluded tha t CNG buses were 2.5 times more prone to fire fatality risk than diesel buses . The study also estimated that CNG bus passengers were at up to two orders of magnitude increased fire fatality risk : an estimated 0.16 fatalities per 100 - million miles compared to (b ased on historical data ) 0.0007 per 100 - million miles for diesel school bus es. This study used historical component failure data from the 63 NHTSA. 2010a. Study of Heavy Truck S - Cam, Enhanced S - Cam, and Air Disc Brake Models Using NADS www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle%20Research%20&%20Test%20Center%20(VRTC)/ca/capubs/811314 .pdf 64 Wong, J. 2009. CNG & Hydrogen Tank Safety, R&D, and Testing www1.eere.energy.gov/hydrogenandfuelcells/pdfs/cng_h2_workshop_8_wong.pdf 65 “Compressed natural gas bus safety: a quantitative risk assessment,” by S. Chamberlain and M. Modarres, in Risk Analysis, April 2005, vol25(2) 377 - 387, at www.ncbi.nlm.nih.gov/pubmed/1587621124 aerospace and process industries to estimate the frequency and consequences of different fire and explosion scena rios . One major limitation of this analysis was its reliance on generic component failure data rather than on CNG - specific hardware failure data . The analysis also did not attempt to model the physics of fatigue and corrosion failure modes of these compone nts, which would be needed to increase the accuracy of the estimates. A 2010 Clean Vehicle Foundation survey of 8,331 natural gas utility, school bus, municipal, and business fleet NGVs that traveled 178.3 million miles 66 indicated that the injury rate was 37 percent lower than the gasoline fleet vehicle injury rate . The study also reported no fatalities compared with 1.28 deaths per 100 million miles for gasoline fleet vehicles . The reported collision rate for NGV fleet vehicles was 31 percent lower. NGVs w ere involved in seven fire incidents, with only one incident directly attributable to failure of the natural gas fuel system. 67 This study indicates that NGVs may operate more safely than gasoline or diesel vehicles. Ten transit agencies, representing 4,07 1 CNG buses, reported that the mean time between failures (MTBF) for their CNG buses ranged from 58 percent to 80 percent of diesel buses, indicating lower reliability, although not necessarily lower safety. 68 The potential safety issues that respondents r aised were fire safety, explosion, and toxicity and health . However, most respondents did not consider the fire risk of CNG higher than that of diesel . Another survey of rec ent transit industry practice drew on seven transit agencies, which stated that th eir CNG buses performed well and have achieved broad public acceptance . Differences between agencies in hazard and consequence mitigation measures were noted, such as inconsistent implementation of methane monitoring in CNG bus facilities, procedures and a ctions to detect methane, and comprehensive control of strong ignition sources. 69

66 Adams, R. and D.B Horne, 2010b. “CNG Transit Experience Survey 2009 - 2010” (Clean Vehicle Education Foundation and NREL report NRE L/SR - 7A2 - 48814 September 2010) at www.afdc.energy.gov/pdfs/48814.pdf Adams, R. 2010b. CNG Transit Experience Survey (Clean V ehicle Education Foundation) www1.eere.energy.gov/cleancities/pdfs/ngvtf10_trans_lessons_learned.pdf 68 Adams, R. 2010b. CNG Transit Experience Survey (Clean Vehicle Education Foundation) www1.eere.energy.gov/cleancities/pdfs/ngvtf10_trans_lessons_ learned.pdf 69 Friedman, D. N., & Malcosky, N. D. 1995. Compressed Natural Gas Safety in Transit Operations: Clean Air Program h ttp://144.171.11.39/view.aspx?id=57374525 Figure 2 - 4 : CNG Tank Failures Frequencies by Cause 70 To date, there have been relatively few CNG cylinder failure incidents, including only two leading to fatalities 71 , 72 that have occurred on the approximately 115,000 CNG vehicles in the United States There were eight cylinder ruptures in the nine - year period between 1993 and 2001; about one rupture per 56,000 cylinder - years . Thr ee of the eight CNG cylinder ruptures prior to 2002 were caused by glass fiber stress corrosion cracking due to battery acid exposure. Four other tanks ruptured due to severe physical tank damage, and one tank failed due to overpressurization. However, ano ther CNG bus destroyed by an engine fire did not have CNG cylinders explode . In this case, their PRDs opened and released the gas, which was then ignited by the primary fire and produced a jet flame. 73 There have been similar cases of vehicle fires resulti ng in CNG cylinder PRD actuation and subsequent cylinder depressurization. 74 Other

70 Wong, J. 2009. CNG & Hydrogen Tank Safety, R&D, and Testing www1.e ere.energy.gov/hydrogenandfuelcells/pdfs/cng_h2_workshop_8_wong.pdf 71 Clean Vehicle Education Foundation. 2010. How Safe are Natural Gas Vehicles? www.cleanvehicle.org/committee/technical/PDFs/Web - TC - TechBul2 - Safety.pdf 72 Clean Vehicle Education Foundation. 2012. Fatal accident removing cylinder solenoid valve www.cleanvehicle.org/technology/ValveFatality.pdf 73 Gambone, L. 2005. CNG Cylinders 101 www.cleanvehicle.org/technology/CNGCylinderDesignandSafety.pdf 74 Zalosh, R. 2009. CNG and Hydrogen Vehi cle Fuel Tank Failure Incidents, Testing, and Preventive Measures www.mvfri.org/Contracts/Final%20Reports/CNGandH2VehicleFuelTankPaper.pdf26 cylinder failures were attributable to a less catastrophic leakage event, including fewer than 50 Type 1 steel cylinder pinhole leaks and hundreds of Type 4 plastic liner le aks. 75 The CNG safety incident reports provided by the Clean Vehicle Education Foundation and other cited sources show that in most cases incidents occur during or shortly after refueling, or in a CNG vehicle fire. 76 CNG cylinder safety depends on a wide r ange of factors including: • Handling procedures ; • Installation design and procedure ; • Operational and maintenance procedures ; • Inspection program and procedures and inspection personnel qualifications ; • Safety management systems for refueling facilities, vehic le workshops, and parking facilities ; and • Emergency response program and procedures . For example, unauthorized drilling or grinding of cylinder surfaces has been reported in some CNG vehicle workshops . There are also reports of cylinder inspectors walking on roof - mounted composite cylinders on top of a CNG bus during in - situ inspection . Such unsafe work practices may indicate a gap in training for workshop staff and their supervisors, or gaps in the work procedures. 77 The most recent CNG failure occurred as a result of human error when the owner attempted to remove a valve from a cylinder that had not been properly vented. 78 The cylinder exploded, killing the owner. 79 A recent, non - fatal cylinder failure caused a delivery truck explosion in Los Angeles while employees of California Linen Services were refueling, causing serious injury. 80 , 81 In another incident, high outdoor temperature caused pressure to build up inside the fuel tank of a propane powered truck, which activated the PRD . When the driver of the v ehicle tried to stop the leaking

75 Wong, J. 2009. CNG & Hydrogen Tank Safety, R&D, and Testing www1.eere.energy.gov/hydrogenandfuelcells/pdfs/cng_h2_workshop_8_w ong.pdf 76 Hien Ly. 2011. Keeping Up the Good Safety Record of CNG Cylinders www.ngvglobal.com/keeping - up - the - good - safety - record - of - cng - cylinders - 0803 77 Ibid. 78 Cle an Vehicle Education Foundation. 2012. Fatal accident removing cylinder solenoid valve www.cleanvehicle.org/technology/ValveFatality.pdf 79 News On 6. 2012. Broken Arrow Police: Business Owner Killed When CNG Tank Explodes www .newson6.com/story/17393515/broken - arrow - police - call - mans - death - accidential - death 80 NHTSA. 2006. Class 8 Truck Tractor Braking Performance Improvement Study

– Low Coefficient of Friction Performa nce and Stability Plus Parking Brake Evaluations of Four Foundation Brake Configurations www.nhtsa.gov/DOT/NHTSA/NRD/Multimedia/PDFs/VRTC/ca/capubs/DOTHS809753 .pdf 81 CNG Chat. 2009. CNG Tank Failu re in Los Angeles http://cngchat.com/forum/archive/index.php/t - 4581.html27 gas, static electricity caused gas ignition. 82 Both LPG and CNG cylinders have the potential for ignition near a venting PRD. There have been reported complaints about fumes due to vented fuel inside a CNG vehicle . In Tulsa , Oklahoma, 140 public school buses that had used CNG since 1988 were checked following driver complaints . The school district considered installing carbon monoxide detectors in the buses 83 (although the reference noted that NGVs produce 70 - 90 percent less carbon monoxide in the exhaust than conventional vehicles). 84 The literature indicates that some road and environmental conditions pose severe operating environments for pressure vessels : Vehicles may operate in temperature extremes that affect the mechan ical properties of the cylinder . Multiple fills result in repetitive pressure changes that can lead to fatigue cracking over thousands of cycles . Exposure to road environments, including road salt, can lead to corrosion or abrasion, and there is vibration whenever the vehicle is in motion . Incidents such as vehicle fires and collisions can also thermally and/or mechanically damage CNG cylinders. The NHTSA regulations that apply to CNG vehicles are FMVSS 301 (Fuel System Integrity), FMVSS 303 (Fuel System Integrity of Compressed Natural Gas Vehicles) and FMVSS 304 (CNG Fuel Container Integrity). 85 Of these regulations, only FMVSS 301 applies to MD/HDVs, while the other two are only applicable to light - duty vehicles. These regulations specify tests or insta llation requirements for CNG tanks and vehicles to account for each of these potential conditions. 86 Testing of CNG cylinders for in - service safety certification includes damage scenarios such as impact, abrasion, gunshot, and bonfire . Cylinders are design ed not to rupture when fully fueled over six times a day, 365 days a year; far beyond what they will see in service. CNG cylinders (Types 1 - 4) are designed with a pressure safety factor of two, i.e., they should be able to contain a pressure up to twice th e maximum fill pressure. 87 The cylinders are designed for a specific lifetime from 15 up to 25 years, and are required to be permanently labeled with the statement “ This container should be visually inspected after a motor vehicle accident or fire and at le ast every 36 months or 36,000 miles, whichever comes first, for damage and deterioration .” (FVMSS 304, § 571.304, S7.4 (g)) 88

82 Morgenstern, M. 2012. Propa ne tank explodes in McDonald's drive - through www.theblaze.com/stories/propane tank - explodes - in - mcdonalds - drive - through/ 83 Mills, R. 2011. TPS investigates claims that CNG - fueled buses made bus drivers sick; The district says it checked out all 140 CNG buses in its fleet www.krmg.com/news/news/local/tps - investigates - claims - cng - fueled - buses - made bus - /nFhNq/ 84 Natural Gas Vehicles for America. 2012. NGVs and the Environment www.ngvc.org/about_ngv/ngv_environ.html 85 NHTSA. 2009. FMVSS 304 CNG fuel container integrity www.nhtsa.gov/DOT/NHTSA/NVS/Crashworthiness/Alternative%20Energy%20Vehicle%20Systems%20Safety%2 0Research/811150.pdf 86 Wong, J. 2009. CNG & Hydrogen Tank Safety, R&D , and Testing www1.eere.energy.gov/hydrogenandfuelcells/pdfs/cng_h2_workshop_8_wong.pdf 87 Ibid. 88 See FMVSS 304 and ANSI CSA NGV2 standard: “Periodic In - Service Inspection Requirements (Sec. 4.1.4, NGV2):“Each container shall be visually inspected at least every 36 months, or at th e time of any re - installation, for external damage and deterioration...” CNG cylinder inspection guidelines are posted at28 The Clean Vehicle Education Foundation (CVEF) sponsored by the DOE National Energy Technology Lab (NETL) developed a “CNG Fuel Sys tem Inspector Study Guide” 89 with industry stakeholders, which is required for certification of CNG fuel system and cylinder inspectors by CSA America. The CVEF also posted and maintains a comprehensive list of “Codes, Standards and Advisories Applicable to Natural Gas Vehicles and Infrastructure.” 90 The literature indicates that aftermarket vehicle conversions to CNG, which are not within NHTSA’s scope, represent over 50 percent of failure incidents, as shown in Figure 2 - 5 .

Figure 2 - 5 : Prevalence of Aftermarket Conversions in CNG Failures 91 2.2.1.4 Safety Considerations for LNG - Fueled Vehicles From a material properties perspective, LNG poses different potential hazards than compressed natural gas (CNG). The energy de nsity of LNG is greater than for CNG so more fuel can be stored onboard. This makes LNG well suited for Class 7 and 8 trucks that need a greater range. Because it is a cryogenic liquid, spills of LNG can lead to a heavier - than - air vapor cloud that can tra vel horizontally from the spill site and then ignite some distance away. 92 In contrast, CNG is www.transecoenergy.com/pages/CNG_Tank.htm ; and www.cleanvehicle.org/committee/technical/PDFs/Web - TC TechBul1 - ContainerInspection.pdf 89 See http:// cleanvehicle.org/technology/Study_Guide_Final.pdf 90 See Codes, Standards and Advisories Applicable to Natural Gas: www.clean vehicle .org/technology/image/ code .pdf 91 Wong, J. 2009. CNG & Hydrogen Tank Safety, R&D, and Testing www1.eere.energy.gov/hydrogenandfuelcells/pd fs/cng_h2_workshop_8_wong.pdf29 lighter than air, and rises and dissipates when leakage occurs. Because of LNG's extremely low temperature, odorants cannot be added, resulting in a potential in creased hazard in the event of a leak, as workers cannot detect an odor. 93 There is a safety advantage of LNG over CNG: since the tanks are only pressurized to 150 - 230 psi, LNG systems are not exposed to the high - pressure explosion hazard of CNG systems. 94 An LNG refueling station has a higher inventory of cryogenic fuel onsite, and therefore of stored energy, than a pipeline - fed CNG refueling station . Hazards relating to LNG include: fire, cryogenic burns, changes in properties of contacted materials (e.g., cryogenic embrittlement), and asphyxiation (by displacing oxygen) . Ignition can result from contact with hot surfaces, open flames, and sparks, including static electricity. 95 The low number of LNG vehicles currently in service in the United States means there is relatively little statistical safety data to draw on . Approximately 20 - 30 public safety incidents involving LNG vehicles have been reported since 1971 in the United States and Europe. 96 Almost all incidents were vehicle crashes . Fewer than half of the incidents resulted in a loss of cargo and only two of the incidents led to fires. Notably, there have been no fatalities reported from LNG vehicle crashes, and only the drivers of the LNG vehicles have been seriously injured . While the research literat ure indicate that the overall safety record of LNG trucks is good, in 2002 an LNG truck in Spain exploded in a boiling liquid, expanding - vapor type explosion. 97 Penetration of an LNG vehicle fuel tank below the liquid level could result in rapid ejection o f LNG and formation of an ignitable vapor cloud . However, LNG tanks are designed to be more robust pressure vessels than conventional diesel fuel tanks, making a penetration of an LNG tank less likely than for a similarly mounted diesel - fuel tank . The Nati onal Petroleum Council cites several severe crashes or fires of LNG - powered trucks and buses in which the LNG tanks were not penetrated. 98 Some have suggested that the long - term durability of cryogenic fuel tanks still warrants further study. 99 Venting from pressure relief devices on LNG vehicles parked for prolonged periods is expected as the liquefied gas evaporates . As a result, LNG vehicles must be stored outside or in facilities designed to collect and discharge methane vapor releases, so that gas relea ses cannot build up in enclosed spaces .

92 Whyatt, G. 2010. Issues Affecting Adoption of Natural Gas Fuel in Light - and Heavy - Duty Vehicles http://s3.amazonaws.com/zanran_storage/www.pnl.gov/ContentPages/184758856.pdf 93 Friedman, D. M., & Malcosky, N. D. 1996. Liquefied Na tural Gas Safety in Transit Operations: Final Report http://trid.trb.org/view.aspx?id=713273 94 Westport HD. 2012. Servicing Heavy - Duty Natural Gas Trucks: Preparation And Shop Requirements www.automotiveworld.com/webinars/servicing - heavy - duty - natural - gas - trucks - preparation - and - shop - requirements/ 95 Friedman, D. M., & Malcosky, N. D. 1996. Liquefied Natural Gas Safety in Transit Operations: Final Report http://trid.trb.org/view.aspx?id=713273 96 National Petroleum Council. 2012. An Initial Qualitative Discussion on Safety Considerations for LNG Use in Transportation www.npc.org/FTF_T opic_papers/19LNG_Transportation.pdf 97 Ibid. 98 Ibid. 99 Oil a nd Gas Journal. 2012. LNG seen viable fuel for heavy - duty trucks www.ogj.com/articles/2012/06/lng - seen viable - fuel - for - heavy - duty - trucks.html30 A methane explosion occurred inside an LNG - powered 60 - foot articulated bus during servicing in 1992 . The bus had just been delivered and was being readied for LNG operation . Although such repairs are supposed to be performed outdoors, because of inclement weather, the mechanic performed the work in a conventional bus bay . After a gas detector alarm went off, the mechanic overrode it and started the bus engine to move it outside; this ignited the flammable natural gas air mixture inside the bus and blew out all of the windows and roof hatches. 100 Waste Management, Inc. provided a positive case study with its fleet of heavy - duty refuse trucks powered by LNG that have been based at a Pennsylvania facility since 1997. 101 Th is implementation was considered successful by both Mack Truck and Waste Management, with no safety incidents reported . Drivers and refuse workers reported that there was no difference in operation between the propulsion systems . The refuse workers preferr ed the LNG trucks because of their lack of diesel odor and quieter operation . The LNG fuel station was installed with the storage tank underground and was reported to operate well, except for minor problems with the fuel nozzle . Waste Management deployed a pproximately 200 LNG refuse collection trucks in locations throughout California based on the outcome of the pilot fleet. Safety in the design and operation of the LNG refueling infrastructure is partly addressed by National Fire Protection Association (NF PA) Code 57, which requires a drainage containment system to catch any liquid draining from the LNG tank and establishes a minimum distance between the edge of the drainage system and any buildings or property lines . The NFPA codes and standards are volunt ary . Regulatory bodies such as the Federal Energy Regulatory Commission (FERC) may mandate compliance with NFPA standards in safety reviews of LNG facilities . Recent efforts, such the Shell collaboration with Mack and Volvo to develop LNG - fueled trucks, and the expansion of the LNG Flying J network of LNG refueling stations at truck stops in the Great Lakes and Gulf Coast regions 102 may lead to broader adoption of LNG. An indirect safety impact of LNG - fueled MD/HDVs could also be an increase in the number o f tanker trucks transporting LNG to many more refueling stations. This would increase the potential for road incidents involving LNG tanker trucks . However, if fueling stations were to perform their own liquefaction, the current natural gas pipeline distri bution system could be used instead of tanker trucks . This would reduce the existing hazards from hauling diesel and gasoline fuel on roads and highways. 103

100 F oss, M. M. 2006. LNG Safety and Security www.beg.utexas.edu/energyecon/lng/documents/CEE_LNG_Safety_and_Security.pdf 101 Clark, K., Paul, N.. Clark, N. 2001. Waste Management's LNG Truck Fleet Final Results www.afdc.energy.gov/pdfs/waste_lng_final.pdf 102 See http://breakingenergy.com/2013/04/23/natural - gas - in - transport - tomorrow - s - fuel - today/ 103 National Petroleum Council. 2012. An Initial Qualitative Discussion on Safety Considerations for LNG Use in Transportation at www.npc.org/FTF_Topic_papers/21 - LNG_in_Transportation.pdf31 2.2.1.5 Findings and Conclusions This literature review did not produce any clear safety contraindications t o the use of CNG or LNG fueled vehicles . It did however, identify some educational and operating procedure gaps and the potential regulatory opportunity to refine fuel system and maintenance facility standards . Robust training for people who handle natural gas, as well as the sound design and manufacture of natural gas storage tanks, may reduce the potential for leaks, tank ruptures, fires, and explosions. Both CNG - and LNG - powered vehicles present hazards distinct from those of diesel vehicles, and call fo r distinct engineering and process controls to assure safe operability . However, based on the reported incident rates of NGVs and the experiences of adopting fleets, it appears that NGVs can be operated at least as safely as diesel MD/HDVs . Using natural g as instead of diesel fuel helps fleets comply with the MD/HD greenhouse gas rules that require up to 20 percent emissions reduction by 2018 . There are currently no generally accepted codes and building standards for facilities that house CNG/LNG vehicles but which do not include a fueling facility ; thus , facility safety is handled at the local level by fire marshals. 104 , 105 Natural gas is lighter than air, so ventilation rates near the ceiling should be high enough to disperse the gas well before it reaches t he lower flammability limit . Since LNG vapor initially stays low in case of a leak, it is recommended that enclosed LNG vehicle facilities install only classified (explosion - proof) electrical wiring and equipment in all maintenance facility work areas, bot h at low elevations and near the ceiling. It is possible to reduce such potential hazards by eliminating potential ignition sources within the facility. 106 In addition, combustible gas detection and alarm systems could be installed. 107 Essentially the same safety procedural requirements applicable to CNG fleets are relevant to LNG maintenance facilities, with one significant difference . Since LNG vehicles are expected to normally vent natural gas from LNG tank PRVs, all maintenance and storage locations shou ld be equipped with a device to connect to PRV outlet and vent escaping gas at the building roof level . A lternatively, LNG vehicles should be de - fueled before entering the facility . This is not necessary for CNG vehicles, which are not expected to vent gas from their PRDs except in the event of vehicle fire or equipment failure . Unlike for CNG vehicles, there is limited data on modifying maintenance facilities to accommodate LNG vehicles, and further facility standards development and their enforcement are warranted. Although the NHTSA regulatory mission does not cover the safety of and vehicle fueling interfaces, they impact both vehicle highway safety, and the adoption of alternative - fuel vehicles.

104 Reich, S. L., & Kolpakov, A. 2011. Tracking Costs of Alternatively Fueled Buses in Florida www.nctr.usf.edu/2011/12/tracking - costs - of - alternatively - fueled - buses - in - florida - 2/ 105 Westport HD. 2012. Servicing Heavy - Duty Natural Gas Trucks: Preparation And Shop Requirements https://s3.amazonaws.com/automotiveworld/presentations/12 - 19 - 12 - Servicing+Heavy - Duty - Natural - Gas - Trucks.pdf 106 NHTSA. 2010a. Study of Heavy Truck S - Cam, Enhanced S - Cam, and Air Disc Brake Models Using NADS www.nhtsa.gov/DOT/NH TSA/NVS/Vehicle%20Research%20&%20Test%20Center%20(VRTC)/ca/capubs/811314 .pdf 107 Adams, R. 2010a. CNG Transit Experience Survey www1.eere.energy.gov/cleancitie s/pdfs/ngvtf10_trans_lessons_learned.pdf32 The literature indicates that a number of preventive and safe handling procedures would ensure the safety of vehicles, personnel, and facilities. These include: • Equipping LNG storage vessels with redundant pressure release valves to prevent an unsafe buildup of pressure when the LNG warms over time and changes t o a gaseous state . • Emptying the LNG tanks or reclaiming the venting gas if a vehicle is parked for prolonged periods. 108 During defueling of the LNG vehicle, 30 percent of the fuel is typically lost in transfer; thus defueling could only occur outdoors or in a properly ventilated indoor facility. 109 Chemical exposure of CNG cylinders could be avoided through proper containment or isolation, e.g., from road salt exposure or battery acid. 110 • Proper insulation, orientation and ventilation of hot components are also critical to safety. 111 • Electric accessory systems are recommended on board NGVs to reduce the risk of a vehicle fire. 112 CNG cylinders should be anchored at all times to prevent rocketing should a rupture occur. 113 Fleets with vehicles that have rooftop CNG cylinders could develop and follow Standard Operating Procedures (SOP) to avoid collisions with low garage doors, overpasses, etc . • The literature indicates that best practices for proactive maintenance and inspection and for driver training would help prevent hose fires or brake fires that could lead to a CNG/LNG fuel tank venting . • Personnel safety training such as strict enforcement of "no smoking" policies, the use of non - sparking tools, and the use of personal protective equipment would also reduce operational CNG/LNG hazards. 114 Some revisions to fuel tank fire exposure testing and to tank thermal protection and inspection to prevent future incidents are recommended in the literature . One source specifically recommends expanding the cylinder certific ation test - to - test survivability against a fire localized away from the PRD, instead of against a bonfire that equally heats the cylinder and the PRD. 115

108 National Petroleum Council. 2012. An Initial Qualitative Discussion on Safety Considerations for LNG Use in Transportation www.npc.org/FTF_Topic_papers/ 21 - LNG_in_Transportation.pdf 109 Westport HD. 2012. Servicing Heavy - Duty Natural Gas Trucks: Preparation And Shop Requirements https://s3.amazonaws.com/automotiveworld/presentations/12 - 19 - 12 - Servicing+Heavy - Duty - Natural - Gas - Trucks.pdf 110 Lapetz, J. 2009. Safety Warning: Acid Exposure of Vehicular CNG Cylinders www.ngvglobal.com/safety warning - acid - exposure - of - vehicular - cng - cylinders - 09 11 111 Adams, R. 2010a. CNG Transit Experience Survey www1.eere.energy.gov/cleancities/pdfs/ngvtf10_trans_lessons_learned.pdf 112 Ibid. 113 NHTSA. 2010a. Study of Heavy Truck S - Cam, Enhanced S - Cam, and Air Disc Brake Models Using NADS www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle%20Research%20&%20Te st%20Center%20(VRTC)/ca/capubs/811314 .pdf 114 Ibid. 115 Wong, J. 2009. CNG & Hydrogen Tank Safety, R&D, and Testing www1.eere.energy.gov/hydrogenandfuelcells/pdfs/cng_h2_workshop_8_wong .pdf33 2.2.2 Biodiesel Biodiesel is a domestically produced renewable fuel that can be manufactured from vegetable oi ls, animal fats, or recycled restaurant grease . Biodiesel consists of fatty acid alkyl esters, fatty acid methyl esters, or long - chain mono alkyl esters . Like petroleum diesel, biodiesel is used to fuel compression - ignition engines, which run on petroleum diesel, but it is cleaner burning . Biodiesel can be blended and used in different concentrations, including B100 (pure biodiesel), B20 (20 percent biodiesel, 80 percent petroleum diesel), B5 (5 % biodiesel, 95 % petroleum diesel) and B2 (2 % biodiesel, 98 % pe troleum diesel). B20 is the most common biodiesel blend in the United States. The EPA highlights the benefits and disadvantages of using biofuel blends. Disadvantages include: concerns about B100's adverse impact on engine durability and unsuitability for use at low temperature due to increase in viscosity; lower fuel economy and power (10 % lower for B100, 2 % for B20); current higher costs; and a possible increase in nitrogen oxide emissions. 2.2.2.1 Penetration/Adoption Between 2001 and 2011, domestic biodiesel production has increased from virtually zero to approximately one billion gallons per year (Figure 2 - 6) . With the recent addition of Mack and Volvo Trucks, more than 65 percent of diesel vehicle manufacturers in the U.S. market now support B20 or higher bi odiesel blends . Volvo and Mack are among the first OEMs to extend B20 approval both to their new 2010 EPA emissions certified engines as well as to their older legacy models. 116 Moreover, the first hybrid - electric trucks to support the use of B20 biodiesel blends were recently introduced, further expanding the potential for biodiesel adoption. 117 Blends up to B20 can be used in existing equipment without modification . In September 2011, Alliant began to use soybean - based fuel with B5 in 126 utility trucks . Th e vehicles using the blended fuel are International straight trucks, including trenchers, digger derricks, tractors, and bucket trucks. 118 According to the latest APTA survey, at least 40 public transit agencies in North America operate buses running on biof uels. 119 The San Francisco Municipal Transportation Agency (SFMTA) has the largest municipal biodiesel fleet in the United States with 512 vehicles using B20

– including both biodiesel and biodiesel - hybrid buses. In 2011, biodiesel fueled about 8 percent of U.S. buses. 120 In 2011, biodiesel fueled about 8 percent of urban transit buses.

116 Biodiesel Magazine. 2012. Mack and Volvo Trucks join growing list of B20 supporters www.biodieselmagazine.com/articles/8470/mack - and - volvo - trucks - join - growing - list - of - b20 - supporters 117 Construction Business Owners. 2012. Hino Trucks Honored at Biodiesel Conference www.construc tionbusinessowner.com/topics/hino - trucks - honored - biodiesel - conference 118 Bennett, S. 2008. Allian t Switches Fleet Vehicles to Biofuels www.worktruckonline.com/Channel/Fuel Management/Article/Story/20 08/07/Alliant - Switches - Fleet - Vehicles - to - Biofuels.aspx?prestitial=1 119 See APTA 2012 “Transit on the cutting edge of clean technologies” at www.apta.com/resour ces/statistics/Documents/Transit - Clean - Technology.pdf 120 Gentry, W. 2012. Statement of William Gentry, President, Gentry Trailways and on behalf of American Bus Association and United Motorcoach Association Subcommittee on Highways and Transit, House Transportation and infrastructur e Committee, U.S. House of Representatives www.gpo.gov/fdsys/pkg/CHRG 112hhrg75852/html/CHRG - 112hhrg75852.htm34 Biodiesel vehicles accounted for about 7 percent of the new buses and more than 14 percent of the new demand. 2.2.2.2 Benefits Although biodiesel contains about 8 percent less energy per gallon than petroleum diesel, corresponding to a 1 - 2 percent decrease in energy density and a commensurate FE penalty, engines operating on B20 blends have similar fuel consumption, horsepower, and torque to engines running on petroleum diesel . Most B 20 users reported no noticeable difference in performance or fuel economy, according to the DOE/AFDC sources cited. B20 has a higher cetane number (a measure of the ignition value of diesel fuel) and higher lubricity (the ability to lubricate fuel pumps an d fuel injectors) than petroleum diesel. 121 B20 and lower - level blends generally do not require engine modifications

.

Figure 2 - 6 : U.S. Biodiesel Production and Consumption 122 Compared with using petroleum die sel, using biodiesel reduces tailpipe emissions of unburned hydrocarbons (HC), carbon monoxide (CO), sulfates, polycyclic aromatic hydrocarbons, nitrated polycyclic aromatic hydrocarbons, and particulate matter (PM). The reductions increase as the amount o f biodiesel blended into diesel fuel increases . B20 has been shown to reduce PM emissions 10 percent, CO 11 percent, unburned HC 21 percent, and carbon dioxide emissions by 15 percent. 123 In addition, retrofit diesel oxidation catalysts (DOCs) and diesel p articulate filters (DPFs) can operate effectively on vehicles using a biodiesel blend fuel up to B20 provided that

121 DOE Alternative Fuels Data Center. 2012. Biodiesel Blends www.afdc .energy.gov/fuels/biodiesel_blends.html 122 DOE EERE. 2012a. Alternative Fuels and Advanced Vehicles Data Center Natural Gas at www.afdc.energy.gov/fuels/natural_gas.html 123 DOE Alter native Fuels Data Center. 2012. Biodiesel Blends www.afdc.energy.gov/fuels/biodiesel_blends.html -100 0 100 200 300 400 500 600 700 800 900

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011Million Gallons

Production Net Exports Consumption www.afdc.energy.gov/afdc/data/35 this biodiesel blend conforms to appropriate biodiesel specifications, e.g., ASTM Standard D7467. 124 2.2.2.3 Safety Considerations In contrast with pe troleum diesel, biodiesel is nontoxic and contains no hazardous materials. 125 It causes less damage than petroleum diesel if spilled or released in the environment and it is less combustible. The flashpoint for biodiesel is higher than 150°C, compared to 52 °C for petroleum diesel . Biodiesel is also safe to handle, store, and transport. 126 When conditions do not permit biodiesel - fueled vehicles to return to their base, they can be refueled with conventional diesel . Since biodiesel vehicles are essentially bi - f ueled, there is no increased risk of vehicle stranding. 127 Operational safety concerns include: • Higher biodiesel blends have a solvent effect that can clean a vehicle's fuel system and release sludge deposits accumulated from previous petroleum diesel use. The release of these deposits may initially clog filters . • Biodiesel blends can gel at temperatures below 20 degrees Fahrenheit if the manufacturing process leaves too much glycerin in the fuel. 128 • Since biodiesel is a rich food source, microbial filter - c logging may occur over time. To combat potential biofouling accumulation, use of a moisture dispersant and biocide may be necessary. 129 The literature provides best practices for biodiesel storage, such as topping off tanks to prevent condensation and keep ing the tank temperature at least 10° F above the cloud point of the blended fuel . There are a number of material compatibility issues associated with B100 that could affect vehicles with engines built before 1994: • B100 can swell or degrade hoses, gask ets, seals elastomers, glues, and plastics with prolonged exposure. 130 Natural or nitrile rubber compounds, polypropylene, polyvinyl, and Tygon materials are particularly vulnerable . Fuel pumps contain rubber valves that may fail . • Extensive contact with c opper, brass, bronze, lead, tin or galvanized surfaces may also accelerate fuel oxidation .

124 Manufacturers of Emission Controls Association (MECA). 2012. What is Retrofit? at www.meca.org/diesel retrofit/what - is - retrofit 125 National Biodiesel Board. 2009b. Biodiesel sample material safety data sheet www.biodiesel.org/extpages/search - results?q=msds 126 DOE Alternative Fuels Data Center. 2012. Biodiesel Blends www.afdc.energy.gov/fuels/biodiesel_blends.html 127 Bennett, S. 2008. Alliant Switches Fleet Vehicles to Biofuels www.worktruckonline.com/Channel/Fuel Management/Article/Story/2008/07/Alliant - Switches - Fleet - Vehicles - to - Biofuels.aspx?prestitial=1 128 DOE Alternative Fuels Data Center. 2012. Biodiesel Blends www.afdc.energy.gov/fuels/biodiesel_blends.html 129 DOE Biodiesel Handling and Use Guide. 2009. www.nrel.gov/vehiclesandfuels/pdfs/43672.pdf 130 Ibid.36 However, most engines made after 1994 have been constructed with gaskets and seals that are generally biodiesel resistant. 131 The National Biodiesel Board recommends a regular maintenance and leak inspection schedule for the fuel lines and components of biodiesel MD/HDVs for newer vehicles; this is critical for older vehicles. 2.2.2.4 Findings and Conclusions Biodiesel is a drop - in alternative fuel that can support MD/HDV p rogress toward GHG and criteria pollutant reductions without major capital investment or infrastructure barriers . There is a minor decrease in fuel efficiency due to the 8 percent lower energy density of biodiesel versus petroleum diesel, but the magnitude of the emissions decrease is substantially larger. As for any bi - fueled vehicles, the potential for refueling with petroleum diesel reduces potential safety risks associated with vehicle stranding due to fuel supply shortage or refueling infrastructure li mitations. In conclusion, the literature reviewed and DOE/AFDC resources 132 indicate that biodiesel, as a viable drop - in alternative fuel, has both safety and environmental benefits . 2.2.3 Liquefied Petroleum Gas (Propane) Propane, also known as liquefied petroleu m gas (LPG) or autogas, has been used worldwide as a vehicle fuel for decades . It is stored as a liquid, and has a propane fueling infrastructure that is widespread . Propane is a three - carbon alkane gas (C 3 H 8 ) . Stored under pressure inside a tank, propane turns into a colorless, odorless liquid . As pressure is released, the liquid propane vaporizes and turns into gas that is used for combustion . Propane is a non - toxic, non carcinogenic, and non - corrosive fuel. It is insoluble in water and does not impact gr oundwater, surface water, or soil. 133 An odorant, ethyl mercaptan, is added for leak detection. 134 Propane has a high octane rating and excellent properties for spark - ignited internal combustion engines . There is interest in propane as an alternative transpo rtation fuel because of its domestic availability, potentially cleaner - burning qualities, and relatively low cost . It is the world’s third most common engine fuel and is considered an alternative fuel under the Energy Policy Act of 1992. 135 When sold as vehi cle fuel, propane can be a mixture of propane with smaller amounts of other gases . According to the Gas Processors Association's HD - 5 specification for propane, it must consist of 90 percent propane, no more than 5 percent propylene, and 5 percent other ga ses, primarily butane and butylene. 136 To compare fuel efficiency on a gallon - to - gallon basis, the

131 National Biodiesel Board. 2009a. B100 Material Compatibility www.biodiesel.org/docs/ffs performace_usage/materials - compatibility.pdf?sfvrsn=4 132 See www.afdc.e nergy.gov/fuels/biodiesel_benefits.html 133 Bertram, M. R, Burham,. A. Bertram. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities www1.eere.energy.gov/cleancities/pdfs/propanepaper09_final.pdf 134 DOE Alternative Fuels Data Center. 2013b. Propane www.afdc.energy.gov/fuels/propane.html 135 Ibid. 136 Ibid.37 energy content of propane is 66 percent that of diesel, thus requiring more propane fuel to travel an equivalent distance even in an optimized engine . 137 Larg er storage tanks can increase range, but the additional weight displaces payload capacity and can slightly increase the consumption of fuel. Propane is stored and handled as a liquid at the fuel dispenser . New nozzles and valves have been introduced that m eet vapor control standards and prevent volatile organic compound (VOC) emissions from escaping from refueling stations . Onboard a vehicle, propane is stored at about 150 pounds per square inch

— about twice the pressure of an inflated truck tire. Under this pressure, propane becomes a liquid with an energy density 270 times greater than the gaseous form. 138 To operate a vehicle on propane as either a dedicated fuel or bi - fuel (i.e., switching between gasoline and propane) vehicle, only a few modifications mus t be made to a gasoline engine . Propane cannot be used in a diesel engine without major modifications since a spark or diesel - pilot ignition system would be required . T he propane tank is typically located under the body of the vehicle. 2.2.3.1 Penetration/Adoption According to the Propane Education and Research Council, there are more than 270,000 on - road propane vehicles in the United States . Many are used in fleet applications, such as police cars, shuttles, street sweepers, and school buses. 139 As shown in Table 2 - 1 , t he Energy Information Administration estimates approximately 64,000 propane MD/HDVs operate in the United States 140 T he World LP Gas Association reports more than 13 million propane - fueled vehicles in operation worldwide. 141 Propane vehicles can either be conversions from gasoline/diesel vehicles or purchased from OEMs. There are about 2,600 propane refuelers in the United States , mostly in California and the southern United States , particularly Texas. 142

137 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities www1.eere.energy.gov/cleancities/pd fs/propanepaper09_final.pdf 138 DOE Alternative Fuels Data Center. 2013b. Propane www.afdc.energy.gov/fuels/propane.html 139 Propane Education and Research Council. 2013. Propane Exceptional Energy http://auto gasusa.org/ 140 Energy Information Administration. 2010. How many alternative fuel and hybrid vehicles are there in the U.S.? www.eia.gov/tools/faqs/faq.cfm?id=93&t=4 141 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities www1.eere.energy.gov/cleancities/pdfs/propanepaper09_final.pdf 142 Motavalli, J. 2012. Making the case for propane: from gas grills to cars and trucks www.cartalk.com/content/making - case - propane - gas - grills - cars - and - trucks38 Table 2 - 1 : Alternative Fuel Vehicles in Use in the United States by Fleet Operators: 2010 143 Medium Duty Heavy Duty Natural Gas
— Total 22,575 28,976 Compressed Natural Gas 22,521 26,000 Liquefied Natural Gas 54 2,97 6 LPG
— Propane 27,771 36,057 School buses fueled by propane are available from several school bus manufacturers, including Blue Bird Corporation and Collins Bus Corporation. 144 In 2012, CleanFUEL U.S.A and Collins Bus Corporation announced the delive ry of 134 propane school buses to First Student, Inc. for serving the Seattle Public Schools and Portland Public Schools. 145 In 2009, there were approximately 2,000 LPG school buses out of a nationwide fleet of about 480,000 . Blue Bird plans to sell another 14,200 buses by 2013 . Propane has also found significant adoption in the paratransit bus market. In 2006, according to the American Public Transportation Association, 3.7 million gallons of LPG were consumed by paratransit buses. 146 In addition to commerci ally available single and bi - fuel propane MD/HDVs, a propane - electric hybrid transit bus is also manufactured by E - bus. 147 2.2.3.2 Benefits Propane fuel costs significantly less than diesel fuel. MD/HDVs fueled by propane have the same horsepower, torque, and towing capacity of diesel - fueled vehicles. 148 Lower maintenance costs are another reason for propane use in high - mileage vehicles . Its high octane and low carbon and oil contamination characteristics have resulted in greater engine life than conventional engines . Because the fuel mixture of propane and air is completely gaseous, cold start problems associated with liquid fuel are reduced. Since propane requires relatively low compression, a pump of only a few horsepower can be sufficient . A home propane refueler c an be purchased for approximately $1,500. 149

143 Energy Information Administration. 2010. How many alternative fuel and hybrid vehicles are there in the U.S.? www.eia.g ov/tools/faqs/faq.cfm?id=93&t=4 144 Propane Education and Research Council. 2013. Propane Exceptional Energy http://autogasusa.org/ 145 Business Wire. 2012. CleanFUEL USA and Collins Bus Corporation Deliver More than 100 Propane Autogas Powered Buses www.businesswire.com/news/home/20121114005626/en/CleanFUEL - USA - Collins - Bus Corporation - Deliver - 100 146 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities www1.eere.energy.gov/cleancities/pdfs/propanepaper09_final.pdf 147 Ibid. 148 Propane Education and Research Council. 2013. Propane Exceptional Energy http://autoga susa.org/ 149 Motavalli, J. 2012. Making the case for propane: from gas grills to cars and trucks www.cartalk.com/content/making - case - propane - gas - grills - cars - and - trucks39 Compared with vehicles fueled by conventional diesel and gasoline, propane vehicles can produce lower amounts of some harmful air pollutants and greenhouse gases, depending on vehicle type, drive cycle, and engine calibration. 150 2.2.3.3 Safety Considerations Similar to natural gas, there are two potential failure scenarios for propane: overpressure due to tank overfill, and unintended ignition (due to leaks or crash) . In the first scenario, to prevent overpressure, most p ropane vehicles have a bleed, or splitter valve attached to the tank. During refueling the valve is opened, releasing vapor from the fuel tank and making room for the liquid propane to enter the tank. 151 Once the tank is filled with 80 percent liquid, additi onal propane will cause the valve to vent liquid fuel . This Overfill Prevention Device (OPD) supplements the automatic stop - fill system on the fueling station side . There are both safety and emissions implications of overfilled fuel tanks, so a pressure re lease device (PRD) is provided to release propane gas if pressure rises in the tank beyond safe levels. 152 The DOE Clean Cities program conducted tests on 105 propane vehicles across seven fleets during fueling . Results showed that the OPDs on nearly 16 per cent of the tanks failed to stop fueling at the necessary level. 153 While the 16 percent OPD failure rate is potentially significant, tanks are also equipped with pressure relief devices specifically to ensure safe pressure levels . If a tank is overfilled during a cool time of day and sits without being used, warmer temperatures later in the day will expand the fuel, which could lead to a fuel release or leak through the pressure relief device. 154 Indeed, overfill is one of three necessary conditions for a p otentially hazardous ignition incident to occur: 1) overfilling leaves inadequate room in the tank for expansion; 2) rising ambient temperatures then cause fuel expansion and release; and 3) an ignition source is present . The physical properties of propan e that are relevant to fire and explosion hazard in the event of a leak are different from the properties of natural gas . Propane, unlike natural gas, is heavier than air . Vapors therefore tend to fall to the ground level and can collect to a flammable lev el in low areas such as service pits. In contrast to natural gas, which dissipates as it rises, the dissipation of propane vapors is primarily based on air movement, and it will dissipate to non - hazardous concentrations faster in windy conditions than in s till conditions.

150 DOE Alternative Fuels Data Center. 2013b. Propane www.afdc.energy.gov/fuels/propane.html 151 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities www1.eere.energy.gov/cleancities/pdfs/pr opanepaper09_final.pdf 152 DOE Alternative Fuels Data Center. 2010. Propane Tank Overfill Safety Advisory www.afdc.energy.gov/techno logy_bulletin_1008.html 153 Ibid. 154 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities www1.eere.energy.gov/cleancities/pdfs/propanepaper09_final.pdf40 Safety training manuals for propane - fueled vehicles include appropriate emergency responses to crash - related propane tank truck fire scenarios . 155 2.2.3.4 Conclusions and Recommendations LPG or propane fueled vehicles can be as operationally safe a s the conventionally - fueled MD/HDVs . The pressurization of the tanks is relatively low, and there are overfill protection measures on both the fuel station and on board tank sides . Although tank OPDs have been found to have a failure rate of about 16 perce nt, excess pressure in the tank resulting from overfill is bled out through a PRD . Similarly, if the pressure in the tank increases due to ambient temperature after it is filled, the PRD is designed to protect against overpressurization . Thus, both the OPD and the PRD would have to fail for a tank to rupture due to overpressurization . No such documented incident could be found in the literature and on the Internet . However, it is critical to eliminate any ignition sources near a propane tank PRD . Best prac tices for fleets in the literature include ongoing inspections of the OPDs, training and educating propane vehicle users about preventing overfill, and having procedures to respond safely to a venting PRD . Safety standards for maintenance, inspection, and emergency response training have been promoted by industry groups, such as the National Propane Gas Association Technology Standards and Safety Committee, the Propane Education and Research Council (PERC), and the Underwriters Laboratory. 156 The Propane Educ ation and Research Council posts resources on codes, regulations and best practices for the safe operation of propane fueled fleets. 157 There are also safety guidelines to be considered when developing propane - refueling infrastructure for MD/HDVs. This inclu des the National Fire Prevention Association’s NFPA 58 Vehicular Liquefied Petroleum Gas Code, which applies to the design and installation requirements of propane refueling facilities. 158 Local fire marshals typically ensure compliance with this code . In a ddition, propane suppliers can provide guidance to MD/HDVs owners and operators on the appropriate amount of propane to be stored on site to adequately meet vehicle fueling needs. 159

155 See “ Tactical response guidelines for propane emergencies: Scenario #8 Propane Fueled Delivery Truck Fire” at www.propanesafety.com/uploadedFiles/Safety/Workforce_Training_programs/Propane_Emergencies_(PE)_Progra m/Energencies_PDFs/Scenario%208.pdf 156 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities www1.eere.energy.gov/cleancities/pdfs/propanepaper09_final.pdf ; and 2007 Propane Education & Research C ouncil, Eight Step Incident Management Process©, Michael Hildebrand and Gregory Noll at www.propanesafety.com /uploadedFiles/Safety/Workforce_Training_programs/Propane_Emergencies_(PE)_Progra m/REVISED_PE3_Text.pdf 157 See postings at www.propanesafety.com/ 158 National Fire Protection Association. 2011. NFPA 58: Liquiefied petroleum gas code www.nfpa.org/aboutthecodes/AboutTh eCodes.asp?DocNum=58&cookie_test=1 159 DOE Alternative Fuels Data Center. 2013b. Propane www.afdc.energy.gov/fuels/propane.html41 2.3 Drivetrain Hybridization and Electrification There are two main types of hy brid technologies that can be used in medium - and heavy - duty vehicles: • Hybrid electric vehicles (HEV) use an electric motor and generator, an energy storage system and power electronics, and an internal combustion engine . Hybrid electric vehicles are avai lable across all weight classes in medium and heavy - duty vehicles.
• Hydraulic hybrid vehicles (HHV) use pressurized hydraulic fluid instead of electric charge as an additional energy storage system and as a power source, to complement the internal combus tion engine. Due to its relatively high power density, but low energy capacity limited by accumulator size, the hydraulic system is eminently suitable for vehicles such as refuse trucks, transit buses, and delivery vehicles that operate in stop and - go traf fic. HEV and EV adoption broken out by technology type includes: • Series Hybrid o Electric. 3,800 transit buses with the BAE series drivetrain are in service globally 160 , including 1,675 in New York City (28 % of the bus fleet). 161 o Hydraulic. 11 Autocar E3 refu se trucks are in use by City of Miami with Parker RunWise drivetrain . UPS, Purolator, and FedEx are operating 48 Freightliner HH series trucks . Autocar E3 refuse trucks are also operating in NC, IN, TX, and CA. • Parallel Hybrid o Electric. 6,000 Eaton hybrid drivetrains are in service worldwide (2,500 electric buses in Asia, 300 electrics in Europe, and 3,200 in North America) . Coca - Cola has operated 142 hybrid box trucks (33,000 lb.) in North American cities since 2008, and larger parallel hybrid drive trucks (55,000 lb.) for its bulk - delivery applications since 2009. 162 o Hydraulic. 100 Eaton “Hydraulic Launch Assist” drivetrains are in service on Peterbilt refuse trucks. • Electric o At least 20 fleets are using Smith or other electric MD box trucks . Frito - Lay Foods is the leading adopter (275 electric trucks), followed by AT&T, Staples, Coca - Cola, Pacific Gas & Electric, and Kansas City Power & Light . In addition, the Santa Barbara Metropolitan Transit District has operated 20 22 - foot electric

160 BAE Systems. 2012. The Heavy - Duty Hybrid www.hybridrive.com/ 161 Gentry, W. 2012. Statement of William Gentry, President, Gentry Trailways and on behalf of American Bus Association and U nited Motorcoach Association Subcommittee on Highways and Transit, House Transportation and infrastructure Committee, U.S. House of Representatives www.gpo.gov/fdsys/pkg/CHRG 112hhrg75852/html/CHRG - 112hhrg75852.htm 162 DO E EERE. 2011. Project Startup: Evaluating Coca - Cola’s Class 8 Hybrid - Electric Delivery Trucks www.nrel.gov/docs/fy11osti/49621.pdf42 buses for over two dec ades . In addition to Smith, at least 4 other manufacturers offer MD/HDV battery electric trucks for commercial sale in the United States :  Electric Vehicles International ,  AMP Electric Vehicles ,  Boulder Electric Vehicles, and  Motiv Power Systems . The fuel consumption benefits of these technologies depend heavily on the vehicle application specific duty cycle . Hybrid drivetrains provide less benefit when operation is mostly steady highway speed, because there is less opportunity for regenerative braking . Hen ce, they are not commonly incorporated into long - haul trucks . In addition, mild hybrid vehicles have electric or hydraulic power systems that are not part of the vehicle's power train but power ancillary equipment like refrigeration or an aerial lift, all owing the primary engine to be shut off during these non - propulsion activities . Electric trucks and buses exclusively rely on an electric motor for propulsion and on an electric storage device for all on - board systems, such as auxiliary power for hotel lo ads for heat, ventilation, lighting, and air conditioning . Typically, EVs draw power from an onboard battery or in some cases from ultracapacitors, overhead catenary, or inductive chargers. Whether they are hydraulic or electric, hybrid MD/HDVs are also ge nerally designed in either a series architecture or a parallel architecture. There is also a two - mode, or compound power split parallel electric hybrid, used in the GM - Allison hybrid electric buses, which can operate in either series, or a parallel configu ration. 163 Series hybrids supply power to drive wheels directly and exclusively from the electric motor or from a hydraulic accumulator tank . In the hydraulic case, the wheels may be powered by hydraulic pressure only for a brief period, such as launching f rom a stop, after which the internal combustion engine takes over . Electric series hybrids typically use a small internal combustion engine (ICE) to continually recharge a battery that powers an electric traction motor . Parallel hybrid vehicles split the p ower transmission to the drive wheels between the ICE and the second power source ( Figure 2 - 7 ). While the range of a hybrid vehicle is usually comparable to an ICE, an electric - only MD/HDV will normally have a reduced range betw een charges . However, manufacturers of two MD electric trucks (E - trucks) claim to have a 100 - mile - per - charge range: the Navistar eStar, with a 2 - ton payload, and the Smith Newton, with an 8 - ton payload. 164 Hino Trucks was honored in 2012 with the National B iodiesel Board Impact Award for being the first manufacturer to support the use of B20 biodiesel blends in a hybrid - electric truck, as well as in its complete product line of class 6 and 7 conventional trucks. 165

163 See http://thisbluemarble.com/showthread.php?t=3155 a nd http://papers.sae.org/2007 - 01 - 0272/ 164 See 2011 DOE/EERE review at www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2011/2011_amr_01.pdf 165 Construction Business Owners 2012. Hino Trucks Honored at Biodiesel Conference www.constructionbusinessowner.com/topics/hino - trucks - honored - biodiesel - conference43 Figure 2 - 7 : Schematic of a Parallel Hybrid - Electric Utility Truck 166 On the transit side, electric buses that wirelessly charge through induction when they are curbed at stops have been developed. 167 Early adopters include Foothill Transit, with 12 Prote rra buses, and the Utah Transit Authority. 168 2.3.1 Penetration/Adoption Hybrid and electric trucks still represent less than 1 percent of all commercial MD/HD trucks on the road in the United States A recent CALSTART survey of 82 fleets that represent 563,408 ve hicles included only 4,381 HV/EVs, including 413 EVs, or 0.78 percent of the total . This relatively low penetration may be due to the lack of national and/or State incentives to offset incremental costs of purchase, the limited amount of in - use performance data - particularly for electric trucks - and the lack of technology standardization . The Energy Information Administration (EIA) reported that there were 865 electric and 1,025 MD/HD hybrid MD/HDVs in 2010. 169 APTA reported that in 2011 more than 35 percent of the public transit bus fleet used alternative fuels or hybrid technology, with 9 percent of buses either diesel - electric, or gasoline electric hybrids, being operated by more than 60 public transit agencies. 170

166 Mims, C. 2009. Hybrid Trucks Are Here for the Long (Medium and Short) Haul; An explosion in the number and kind of commercially available hybrid trucks means battery power isn't just for lightweight commuter vehicles anymore www.scientificamerican.com/slideshow.cfm?id=hybrid - trucks 167 Proterra. 2012. About the EcoRideTM BE35 www.proterra.com/index.php/products/productDetail/C22/ 168 Barry, K. 2012. Induction Charging Comes to Public Transit www.wired.com/autopia/2012/12/induction charging - bus/ 169 See Table at www.eia.gov/tools/faqs/faq.cfm?id=93&t=4 170 “ More than 35% of US public transit buses use alternative fuels or hybrid technology: Public transportation is leading the way in green vehicles: www.apta.com/mediacenter/pressreleases/2013/pages/130422_earth - day.aspx44 Adoption of hybrid MD/HDVs is accelerating . 171 The 2012 industry estimates reported there are 3,500 - 4,500 hybrid trucks currently operating in the United States 172 and 500 - 1,450 electric trucks in North America. 173 More than 150 fleets use hybrid and/or electric trucks, of which there are about 40 mo dels available. 174 Market forecasts predict anywhere from 13,000 to 39,000 hybrid and electric trucks sold annually in the United States by 2015 - 2017. 175 , 176 Early adoption of electric trucks has occurred in State s such as CA and NY that have policies and pro grams to encourage these EVs . Hybridization shows the greatest current benefit in vocational vehicles. 177 The most likely truck application areas for truck hybridization and electrification are municipal, delivery, and utility fleets, which tend to operate at lower speeds with frequent stop - and - go drive cycles, or which remain stopped for extended periods while operating onboard equipment, e.g., an aerial boom or a lift gate . Major truck manufacturers are now competing in the hybrid MD/HDV market niche: Dai mler/Freightliner, International, Peterbilt, Paccar/Kenworth, Navistar, and Volvo/Mack . The electric truck OEMs include Smith, Navistar, Electric Vehicles International, VIA Motors, Quantum Technologies, and Boulder EV . In contrast to the truck market, th ere is already significant penetration of hybrid technology in U.S. transit bus fleets . Large public transit agencies in cities such as New York City, Chicago, Seattle and San Francisco have been at the forefront of adopting hybrid - electric buses, which no w account for about 1 out of every 6 new buses that transit agencies have on order . A few agencies are pioneering plug - in electric hybrids and all - electric buses . By 2011, about 9 percent of buses were diesel - electric or gasoline - electric hybrids and more than 60 transit agencies had such buses in service. 178

171 Mims, C. 2009. Hybrid Trucks Are Here for the Long (Medium and Short) Haul; An explosion in the number and kind of commercially available hybrid trucks me ans battery power isn't just for lightweight commuter vehicles anymore www.scientificamerican.com/slideshow.cfm?id=hybrid - trucks 172 Mathers, J. 2011a. Hybrid Trucks: Creating Jobs, R educing Emissions http://blogs.edf.org/innovation/2011/01/31/hybrid - trucks - creating - jobs - reducing - emissions/ 173 Walkowicz, K. 2012. Medium and Heavy Duty Vehicle Evaluations www1.eere.en ergy.gov/vehiclesandfuels/pdfs/merit_review_2012/veh_sys_sim/vss001_walkowicz_2012_o.pdf 174 Mathers, J. 2011b. Work Trucks and Fuel Consumption: 2011 http://blogs.edf.org/innovation/2011/03/10/work trucks - and - fuel - consumption - 2011/ 175 ABI Research. 2009. Commercial Hybrid Vehicles: A G lobal Analysis of Medium - and Heavy - Duty Hybrid Trucks and Buses www.abiresearch.com/mobile/research/1001997 176 CalStart. 2012a. Best Fleet Uses, Key Challenges, and the Early Business Case for E - Trucks www.calstart.org/Libraries/E Truck_Task_Force_Documents/Best_Fleet_Uses_Key_Challenges_and_the_Early_Business_Case_for_E Trucks_Findings_and_Recommendations_of_the_E - Truck_Task_Force.sflb.ashx 177 CalStart. 2012c. Market Demand Analysis For Hybrid and Electric Trucks 2012 - 2016 178 TRB/TCRP report 132 “Assessment of Hybrid Electr ic Transit Bus Technology,” 2009 at http://onlinepubs.trb.org/onlinepubs/tcrp/tcrp_rpt_132.pdf45 2.3.2 Benefits According to the Transit Cooperative Research Program, diesel - electric hybrid buses can have 14 percent to 48 percent better fuel efficiency than conventional diesel buses. 179 The breakeven perio d of hybrid - electric transit buses for most agencies is approximately 15 years (this will obviously vary depending on current diesel costs), not accounting for reduced brake maintenance costs. 180 With the exception of particulate matter from brake, tire, a nd road wear, 181 an all - electric vehicle has no mobile emissions, or direct fuel consumption . Hybrid drivetrain technologies can significantly reduce fuel consumption and vehicle emissions, depending on the drive cycle and depending on the level of hybridiza tion, from mild to full. 182 Additionally, drivetrain hybridization and use of regenerative braking for energy recovery can reduce maintenance of some vehicle components such as brakes, based on NREL’s 13 month study of Coca Cola h ybrid t rucks. 183 Stored ener gy in an HEV also powers electric - only operation for electric Power Take - Off (ePTO) and auxiliary power generation. 184 Wrightspeed’s “Route” retrofit plug - in hybrid powertrain for MD trucks claims to increase the fuel economy from 12 mpg to 25 - 40 mpg in a me tro drive cycle . Because the factory truck’s engine and transmission are removed, the PHEV drivetrain adds no weight to the vehicle. 185

179 TRB/TCRP report 132 “Assessment of Hybrid Electric Transit Bus Technology,” 2009 at http://onlinepubs.trb.org/onlinepubs/tcrp/tcrp_rpt_132.pdf 180 U.S. transit buses average approximately 30,000 miles per year and diesel buses average approximately 3.5 MPG. This means that diesel buses use on average about 8,600 gallons of fuel per year. At $4.00 per gallon each bus uses $34,400 worth of fuel per year. Most transit agencies will achieve no more than 30% reduction in fuel use, so they will save $10,000/year/bus in fuel costs. According to the American Public Transportation Association, the incremental purchase cost of a hybrid bus compared to a diesel bus is approximately $150,000. 181 www. fhwa.dot.gov/resourcecenter/teams/airquality/brochure/particulatebrochure.pdf 182 ils, H. 2009. Hybrid Solutions for MD Commercial Vehicles www.erc.wisc.edu/documents/symp09 - Cornils.pdf 183 See “The case for Class 8 Hybrids” at http://ev.sae.org/article/11853 184 Freightliner. 2012. Freightliner hybrid trucks www.cleanandgreenvehicles. com/pdfs/M2eHybrid - Brochure.pdf 185 See page 10 of CalStart. 2012d. Wrightspeed brings a CNG plug - in at http://issuu.c om/kfetzer/docs/showtimes_htuf2012_issuu?mode=window&viewMode=doublePage46 Figure 2 - 8 : Hydraulic Hybrid Refuse Truck 186 The demonstrated FE gains f or hydraulic hybrid systems range between 15 percent and 50 percent, due primarily to the 71 percent brake energy recovery, which is significantly higher than that for electric hybrids . Assuming a high kinetic intensity drive cycle, such as the ones used f or a refuse or delivery truck, parallel hybrids are at the lower end of this FE gain range, while series hybrids are at the upper end. 187 A field test by NREL and the United Parcel Service (UPS) measured a 13 - 20 percent FE gain on 11 parallel hybrid step va ns versus 11 conventional vans operated by UPS in Minneapolis. 188 FedEx Ground, Purolator, and UPS report fuel savings of approximately 40 percent in tests of series hydraulic hybrids. 189 Miami - Dade’s Autocar E3 refuse trucks with Parker RunWise burn 36 gal lons per day versus 63 gallons for the conventional trucks. 190 Additionally, up to an eight - fold increase in brake life is reported to reduce brake fade and other brake problems . Parker claims that a series hydraulic hybrid improves drivability, smoothes br aking, and boosts acceleration versus an ICE equivalent. 191 Hybrid systems potentially also allow a vehicle that runs out of fuel or that has an ICE breakdown to still pull off the road or drive to a safe location, which is not possible in an ICE vehicle failure. 186 Cornils, H. 2009. Hybrid Solutions for MD Commercial Vehicles www.erc.wisc.edu/documents/symp09 - Cornils.pdf 187 DeCoster, T. 2012. Parker's hydraulic hybrid technologies www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26445 188 National Renewable Energy Laboratory. 2012. Eighteen - Month Final Evaluation of UPS Second Generation Diesel Hybrid - Electric Delive ry Vans www.nrel.gov/docs/fy12osti/55658.pdf 189 CalStart. 2012a. Best Fleet Uses, Key Challenges, and the Early Business Case for E - Trucks www.calstart.org/Libra ries/E Truck_Task_Force_Documents/Best_Fleet_Uses_Key_Challenges_and_the_Early_Business_Case_for_E Trucks_Findings_and_Recommendations_of_the_E - Truck_Task_Force.sflb.ashx 190 Hybrid Truck Users Forum. 2012. More Parker Hannifin Hydraulic Hybrids http://issuu.com/kfetzer/docs/showtimes_htuf2012_issuu?mode=window&vi ewMode=doublePage 191 DeCoster, T. 2012. Parker's hydraulic hybrid technologies www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&Item ID=2644547 Since electric vehicles produce no tailpipe emissions, they also provide potential health benefits to operators through GHG reduction and complement fuel efficiency benefits . According to Smith Electric, the 20 fleets that are already using Smi th trucks have prevented 15,000 hours of diesel inhalation for their drivers over five years (Figure 2 - 9). 192

Figure 2 - 9 : Smith Electric Truck 193 2.3.3 Safety Considerations NHTSA recognized that potential hazards involving high voltage batteries and battery - related fires are different from those posed by conventionally - fueled vehicles. In January 2012, the agency issued Interim Guidance for Electric and Hybrid - Electric Vehicles Equipped With High Voltage Batteries , applicable to medium and heavy - duty hybrid vehicles. 194 The literature has reported fires that were initiated by, or involved, the energy storage systems of hybrid - electric buses and trucks . For instance, in February 2012, a Zero Truck Co. hybrid electric truck with 24 lithium ion batteries caught fire twice. 195 Firefighters did not handle the high voltage 400 - volt energy storage system (ESS) to avoid electrocution, but waited for the 24 lithium ion batteries to self - extinguish . Even though this battery - rela ted fire led to the release of hydrogen gas, there were no adverse effects as the truck was located outside. 196 Introductions of new HEV/EVs to the market are rapidly increasing, with models from nearly every major OEM in production . One trend is that bat tery capacities are increasing with greater 192 Smith Electric Vehicles. 2012. Smith NTEA Green Truck Summit www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id &ItemID=26498 193 Ibid. 194 See Interim Guidance for Electric and Hybrid - Electric Vehicles Equipped With High Voltage Ba tteries. www.nhtsa.gov/staticfiles/nvs/ pdf/InterimGuide_TowTruck_012012_v3.pdf 195 See http://articles.mcall .com/2012 - 02 - 08/news/mc - allentown - electric - truck - fire - 20120208_1_electric - truck lithium - ion - batteries - truck - box 196 Ibid.48 vehicle electrification, owing to pressure to increase the vehicle range and to increase the range of applications for EVs. 197 Due to their larger market penetration and longer (15 years) operational experience, h ybrid and electric transit buses have more of a safety history than the more recently adopted hybrid electric trucks. Electric and hybrid - electric transit buses have been safely operated by many urban transit fleets . For example, the Santa Barbara’s Munici pal Transit District has operated electric buses for over two decades without any safety incidents and with only minor service interruptions. This transit fleet experience shows that centrally maintained and properly operated electric battery buses have be en operating and will continue to operate safely and reliably. Transit fleet experiences also illustrate potential battery - related hazards . In March 2012, DC Metro recalled NewFlyer/BAE buses after fire problems, although there had been only 10 such incid ents in North America. 198 Fires resulted when debris in the rechargeable energy storage system on the bus roof shorted out the battery pack. The battery packs melted and smoked; however the smoke did not penetrate the passenger space. 199 In 2011, NHTSA recal led over 1,300 hybrid electric Orion VII Daimler 2007 - 2011 buses equipped with Lithium - ion batteries because of the potential for battery - related fire hazards. 200 Problems of smoke and overheating and the potential for fire potential were due to debris accu mulation in the roof - emplaced RESS, which compromised the electrical isolation and discharged or shorted out the battery. 201 As discussed recently in a May 2012 NHTSA workshop and in several SAE/NFPA annual EV Safety summits, the stranded energy in certai n types and chemistries of lithium - ion batteries, which can enable thermal runaway given the right conditions, poses potential post - crash electrocution or fire hazards for HEVs/EVs operators and rescuers. 202 Since the electrical systems of regular diesel ve hicles are low voltage, a typical maintenance garage may not be equipped to safely service high voltage systems in hybrid - electric trucks or buses . A literature review identified several safety best practices for maintenance facilities of hybrid electric M D/HDVs: provide additional electrical safety equipment (e.g., fault ground detection and ground interrupters) and provide electrical safety training of maintenance and emergency response personnel . Specifically, high - voltage battery storage areas, and char ging stations for charging several batteries at a time should be well ventilated and equipped with heat

197 Mackintosh, T. 2012. SAE J2 990 Hybrid EV First and Second Responder Recommended Practice Overview www.sae.org/events/nevss/summit/2012_EV_Safety_Summit_mackintosh.pdf 198 Hedgpeth, D. 2012. Manufacturer needs to repair 47 hybrid buses bought by the Metro system http://articles.washingtonpost.com/2012 - 03 - 28/local/35449072_1_hybrid - buses - new - flyer - bae - systems 199 Ibid. 200 See www.dhses.ny.gov/ofpc/alerts - bulletins/safety/text/2011/20110065.cfm 201 NHTSA. 2011b. Orion VII Li - ion hybrid bus recall www odi.nhtsa.dot.gov/recalls/results.cfm?rcl_id=11V523000&searchtype=quicksearch&summary=true&refurl=rss 202 Harris, C. 2012. Overview of NHTSA EV Safety Program October 2012 www.sae.org/events/nevss/summit/2012_EV_Safety_Summit_harris.pdf ; and www.sae.org/calendar/techsess/203434.pdf49 and smoke detectors to prevent overheating and the build - up of dangerous gases from overheated batteries during charging. 203 Since there are major differ ences between light - duty HEVs/EVs and their MD/HDV counterparts in terms of their power, size, weight and body ranges, appropriate consensus safety standards are being developed . These may mirror FMVSS 305 power level and battery sub - system crash integrity as assured by the NHTSA TP 3015 - 01 lab - testing procedure, which only applies to vehicles with a GVW less than 10,000 pounds . 204 For instance, OEMs have adopted voluntary safeguards and national and international specifications and standards for heavy - duty vehicle rechargeable storage system (RESS) safety testing . The SAE Truck and Bus Committee has issued Standard J2910 “Recommended Practice for the Design and Test of Hybrid Electric Trucks and Buses for Electrical Safety.” 205 The SAE safety performance tes ts for high - voltage vehicle ESSs include 206 1. Vibration: Pack Test 2. Thermal Shock: Pack Test 3. External Short Circuit Protection: Pack Test 4. Overcharge Protection: Vehicle Test 5. Over - Discharge Protection: Vehicle Test 6. Over Temperature Protec tion: Vehicle Test 7. Under Temperature Protection: Vehicle Test 8. Fire Resistance

– Short Duration: Pack Test 9. Fire Resistance

– Long Duration: Pack Level 10. Vehicle Crash Evaluations: Vehicle Test 11. Water Intrusion Test: Vehicle Test Eaton, a m ajor hybrid drivetrain manufacturer lists seven engineering and conspicuity measures to reduce the risk of stray energy and electrocution. 207 These include orange coloring of all high voltage lines, cable disconnect interlocks, ground fault detection, isolat ion from the vehicle chassis, and an ignition interlock that electrically isolates the ESS when the vehicle ignition is

203 Reich, S. L., & Kolpakov, A. 2011. Tracking Costs of Alternatively Fueled Buses in Florida www.nctr.usf.edu/2011/12/tracking - costs - of - alternatively - fueled - buses - in - florida - 2/ 204 See Sept.11, 2008 TP 305 - 01, Laboratory Test Procedure for FMVSS 305, Electric Powered Vehicles: Electrol yte spillage and electric shock protection” at www.nhtsa.gov/Vehicle+Safety/Test+Procedures 205 NHTSA. 2012. Electric Vehicle Safety Technical Symposium www.nhtsa.gov/staticfiles/nvs/pdf/EV_Symposium_agenda.pdf 206 Wilson, K. 2012. SAE Cooperative Research Project to Develop Repeatable Safety Performance Test Procedures for Rechargeable Energy Storage Systems (RESS) www.sae.org/events/nevss/summit/2012_EV_Safety_Summit_wilson.pdf 207 Eaton. 2011. Eaton Hybrid Electric Power Systems Emergency Response Guide TRDR1100 www.roadranger.com/rr/CustomerSupport/Support/LiteratureCenter/index.htm?litlibtarget=116291921238750 off . Truck OEMs are backing the reliability of their HEVs . Freightliner, for example, provides a 3 - year/150,000 mile warranty on the hyb rid system. 208 The emergency response guide for Eaton HEV drivetrains outlines safety procedures for first responders that are similar to current methods used for ICE trucks. 209 The guide notes that the lithium salt, which is dissolved in an organic solvent, will not normally spill or leak if the battery is damaged. If the 1.2 gallons of contained electrolyte does leak from the battery system, it can be wiped up by a towel . In a non - fire situation, no toxic gases are emitted, and there is no inhalation hazard . If there is a fire, inhaling gas released by the battery is dangerous and the guide advises moving immediately to fresh air and seeking medical attention. Hydraulic hybrid vehicles entail a different set of potential safety concerns than electric hybrids . The emergency response guide for Parker drivetrains states that two 20 - gallon hydraulic accumulators are constantly pressurized to 2 , 450 psi with nitrogen gas . Nitrogen gas is not flammable and is chemically inert, but the pressure of the nitrogen gas cou ld propel objects at deadly speed if the tank is pierced or broken . Hoses in the cradle contain 5400 - psi hydraulic fluid . A hose puncture could lead to severe injection wounds by expelling high - pressure fluid, and a spray of leaking hydraulic fluid would b e explosively flammable . If a hose in this system were to get loose, it could violently flail and cause death or injury by impact . If the containers of gases were pierced or opened, an explosion could also occur. There are a variety of safety features inco rporated in the hydraulic hybrid to prevent personal injury or component damage in the event of system pressure leaks or electrical failure . Safety features include a variety of fuses, discs, and valves activated by set points in velocity, temperature, or pressure. Additionally, orange coloring marks all high - pressure hoses. 210 As one data point, following 15 months of testing HHVs, Miami - Dade County has not encountered any safety problems and has reported uptime of 99 percent in South Florida refuse collect ion service 211 Parallel hybrid vehicles offer a potential safety advantage over series hybrid vehicles in the event that the hybrid drive unit fails, since the diesel powertrain remains fully functional. 212 Series hybrid vehicles are not redundantly powered, so if there is a significant hydraulic leak or a traction motor or battery failure, the vehicle is disabled and must be towed . It is worth noting that a series HH drivetrain adds about 1,700 lbs. over a conventional drivetrain to the GVW of a truck . Thi s is approximately 5 percent additional weight, which may affect the handling or stopping distance of the vehicle as well as its maximum payload.

208 Freightliner. 2012. Freightliner hybrid trucks www. cleanandgreenvehicles.com/pdfs/M2eHybrid - Brochure.pdf 209 Eaton. 2011. Eaton Hybrid Electric Power Systems Emergency Response Guide TRDR1100 www.roadranger.com/rr/CustomerSupport/Support/LiteratureCenter/index.htm?litlibtarget=1162919212387 210 Parker Hannifin Corporation. 2012. Parker RunWise Adv anced Series Hybrid Drive AutoCar E3 First Responders Guide 211 Hybrid Truck Users Forum. 2012. More Parker Hannifin Hydraulic Hybrids http://issuu.com/kfetzer/docs/showtimes_htuf2012_issuu?mode=window&viewMode=doublePage 212 Freightliner. 2012. Freightliner hybrid trucks www.cleanandgreenvehicles.com/pdfs/M2eHybrid - Brochure.pdf51 2.3.4 Findings and Conclusions Hybrid - electric transit buses have demonstrated a long and safe operational history, with vehicle handling and a breakdown rate that are comparable to conventional ICE buses. 213 The recent NHTSA/ODI recall of l ithium - ion RESS packages in Orion VII and Xcelsior hybrid buses 214 for potential battery - related fire hazards indicate that unforesee n safety issues occurred . The roof placement of batteries to allow for passive cooling also allowed debris and moisture to accumulate that could cause battery short - outs with the potential for a fire. To date, no safety incidents have been reported in th e shorter history of hybrid - hydraulic trucks . The underlying hydraulic technology is much more mature than that of HEVs . Multiple fail - safe design features prevent electrocution during operation of hybrid - electric vehicles, although post crash hazards due to stranded energy may be present . In contrast to an ICE vehicle, hybrid vehicles (in particular parallel models) offer redundancy of propulsion: if one power source fails, the other can still propel the vehicle, even if it is for a short distance on elect ric or hydraulic system power alone. Inputs from SMEs suggest that the full vehicle testing and modeling of EVs/HEVs is more limited for small volumes of production and downstream integration of novel RESS units by body - builders than it is for high - volume production of ICEs . Continued evaluation of best practices and lessons learned from hybridization and electrification across all adopting MD/HDV fleets would likely help to prevent failure of novel FE subsystems. 2.4 ITS and Telematics for Fuel Efficiency and Operational Safety 2.4.1 Driver and Vehicle Monitoring Technologies that influence MD/HDV fuel efficiency can also affect driver behavior and operational safety, and vice versa . These t elematics technologies include GPS - based route navigation, on - board computer s that track driver and vehicle behavior, and associated mobile communications and displays that convey this information in real time to the vehicle driver and to fleet managers. Information that is typically gathered includes route choice, speed, braking, and acceleration, measured using devices such as accelerometers, GPS, and on - board cameras . Telematics systems are intended to correct the behavior of MD/HDV drivers over time to increase their fuel efficiency, either by providing real - time feedback on th eir driving performance or by relaying performance information to supervisors for individual driver coaching. There are various implementations of telematics for route optimization, location, and navigation that simultaneously address the fuel efficiency and safety of vehicle operations . Camera - based

213 See series of NREL reports comparing new York City Transit hybrid, CNG and diesel buses at www. nrel.gov/vehiclesandfuels/fleettest/pdfs/42534.pdf and at www.nrel.gov/vehiclesandfuels/fleettest/research_hybrid_nyc.html 214 See Recall notice at www odi.nhtsa.dot.gov/owners/SearchResults?searchType=ID&targetCategory=R&searchCriteria.nhtsa_ids=11V523000 &refurl=rss52 systems such as SmartDrive record comprehensive video - based data from the road . High acceleration or force thresholds are used to filter the events that are captured . The event data are reviewed for fuel consu mption and safety performance by off - site analysts, thus informing the fleet managers for driver coaching and training. 215 Non - camera based systems such as GreenRoad 216 (Figure 2 - 10) use accelerometers and other sensors for real - time assessment and visual fee dback for driving maneuvers, e.g., with a green/yellow/red performance meter . In addition to maintaining safe and fuel - efficient driver behavior, ITS technologies are also intended to prevent crashes, offering additional safety benefits. Although not clas sified as FE technologies, the Insurance Institute for Highway Safety (IIHS) has recommended four ITS crash avoidance technologies it claims have the potential to prevent or mitigate one - fourth of the 384,000 annual large truck crashes, including one - third of injury crashes and about 20 percent of the 4,100 fatal crashes. 217 2.4.1.1 Penetration/Adoption The penetration rate in the total population of non - privately owned commercial vehicles is estimated to increase from 7.9 percent in 2011 to 16.4 percent in 2016. 218 The market leaders include a range of different companies. Qualcomm Enterprise Services is ranked as the largest, with an estimated total installed base of approximately 450,000 units in North and Latin America . Trimble which previously mainly focused on s ervice fleets now has a total installed base of 360,000 units following the acquisition of PeopleNet. Other companies focusing on service fleets include FleetMatics, Networkfleet, NexTraq and Wireless Matrix. Several additional companies have a broader mar ket scope, covering both light and heavy vehicles. Examples include Telogis, Teletrac, Zonar Systems and Webtech Wireless. GreenRoad states it is used by more than 85,000 drivers worldwide , in a wide range of vehicle types, including EV vans, and NG tracto rs. “Green telematics” that are claimed to save fuel, reduce emissions, and optimize routing have wide market penetration and have been adopted early by large MD/HDV fleets, such as Frito Lay. 219

215 SmartDrive Systems. 2012. SmartDrive www.smartdrive.net/ 216 http://greenroad.com 217 See “Large trucks to benefit from technology designed to help prevent crashes,” IIHS Status Report, Vol. 45, No 5, May 20, 2010. 218 www.prnewswire.com/news - releases/fleet - management --- world - 2012 - 166386546.html 219 Frito - Lay North America. 2011. Frito Lay Frito - Lay Electric Delivery Truc ks hit the Green Streets of Orlando www.pepsico.com/PressRelease/Frito - Lay - Electric - Delivery - Trucks - Hit - the - Green - Streets - ofOrlando12022011.html53 Figure 2 - 10 : GreenRoad On - Board Driver Behavior and Telematics 2.4.1.2 Benefits According to one telematics manufacturer, Telogis, 220 the FE performance spread between the best - and worst - trained drivers is about 25 percent. 221 The Telogis Fleet telemetrics program monitors w hen fleet vehicles violate defined speed parameters, including posted speed limits; when “hard” braking occurs; and engine off/on status, which can be critical when loading and offloading hazardous cargo. 222 GreenRoad claims that in a case study its users’ fuel consumption decreased 6 - 15 percent, 223 while Telogis claimed its telematics package demonstrated 11 percent fewer VMT through route optimization and monitoring driver behavior for subsequent coaching. 224 A comparison of telematic deployments for real - tim e fleet management and improved fuel economy found that the benefits do include safer driving, with a 50 percent crash reduction and lower insurance and crash - related costs . Additionally, the systems have led to less aggressive acceleration and significant ly decreased speeding . Altogether, these behavioral changes add up to 10 percent reduced fuel consumption, a longer vehicle life, and a positive ROI in 3 - 6 months. 225 GreenRoad claims that its system decreases maintenance for vehicle wear by up to 10 perce nt. 2.4.1.3 Safety Considerations The Federal Motor Carrier Safety Administration and the NHTSA jointly conducted the Large Truck Crash Causation Study (LTCCS) to better understand the critical events that increase the 220 See www.telogis.com/solutions/mobile/n avigation/ 221 Koch, J. 2012. Technologies for increasing fuel efficiency and eliminated fuel waste www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26464 222 Telogis Fleet Safety. www.telogis.com/benefits/improve - driver - safety - and - asset - security 223 GreenRoad. 2012. http://greenroad.com/ 224 Koch, J. 2012. Technologies for increasing fuel efficiency an d eliminated fuel waste www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26464 225 Renaud, P. S., & Coleman, D. 2012. Telematics: real - time fleet management and improved fuel economy www.ntea.com/worktruckshow/index.aspx?id=2546954 probability of large truck crashes. 226 Fatigue , alcohol, and speeding were the most common critical events for the 87 percent 227 of large truck crashes attributed to driver error , as shown in Table 1 - 3 above, that list ed the numbers and percentage of trucks in volved in crashes by safety critical factor s . Only 10 percent of crashes were attributed to vehicle issues, and only 3 percent to environmental reasons such as snow or ice. NCSA crash reports do not include FE technologies or alternative fuel tanks on state crash report forms. Telematic technologie s claim to both reduce fuel consumption and to improve safety by monitoring driver performance, including either displaying immediate feedback to the driver or recording unsafe operations for later coaching. GreenRoad claims that its users’ crash - related c osts decrease 50 - 70 percent (including lower insurance premiums) compared to baseline fleet operations . Telogis claimed that its telematics package leads to a 90 percent reduction in speeding events after one year of use; in one case study, Telogis demonst rated 11 percent fewer VMT through route optimization and monitoring driver behavior for deviations and to support coaching. 228 Although no crash reduction figures are provided, GreenRoad and Telogis data indicated that lower VMT and reduced speeding genera lly correlated with fewer crashes. At the same time, a potential safety concern related to telematics systems that provide real - time feedback to drivers is the potential for additional driver distraction from these systems. 2.4.1.4 Findings and Conclusions Driver behavior was a critical causal safety factor in the LTCCS for 87 percent of large truck crashes . By all indications, telematics and crash avoidance systems offer potential improvements in both driver safety performance and fuel efficiency . Both camera and non - camera based telematics setups are currently available and appear to be well accepted by MD/HDV fleet drivers . 2.5 FE Technologies Affecting Operations 2.5.1 Speed Limiters Speed limiters (or speed governors) are on - board electronic control modules that limit t he top speed of a vehicle to a pre - set value . They are intended to reduce the fuel consumption of MD/HDVs when traveling on highways . Since the devices also prevent excessive speeding, their safety effects have been a recurring issue in truck safety discus sions . Heavy - duty trucks are delivered from the factory equipped with speed limiting devices that can be configured by the

226 FMCSA. 2006. Report to Congress on the Large Truck Crash Causation Study www.fmcsa.dot.gov/facts research /research - technology/report/ltccs - 2006.htm#TABLE1 227 This figure refers to all drivers in a crash. 228 Koch, J. 2012. Technologies for increasing fuel efficiency and eliminated fuel waste www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=2646455 vehicle owner . However, these devices may sometimes be disabled by trucking companies in order to maximize operating speed and save t ravel time, as reported in Quebec, Canada. 229 2.5.1.1 Penetration and Adoption Electronic control modules that can be programmed to limit speed have been standard equipment in all trucks for a number of years . Typically, the top speed is programmed at the factory ac cording to buyer specification; many U.S. trucking companies already are programming to 68 mph or slower . Estimates on how many U.S. fleets already use speed limiters ranges from 60 to 80 percent. 230 To date, 33 countries (excluding the United States ) includ ing the world's leading developed nations, require speed limiters in heavy - duty vehicles. 231 The EU has required trucks and buses to be limited to 56 mph since 1994; Australia to 62 mph since 1990; Japan to 56 mph since 2003; and Quebec and Ontario to 65 mp h since 2009. 232 A Canadian study of the environmental and safety implications of speed limiter requirements for trucks 233 reported maximal safety gains at 90 kph on uncongested roads, with safety benefits decreasing at higher speeds (105 kph) and greater tra ffic congestion levels . The UK and other countries have also imposed speed limiter requirements, resulting in road safety improvements. 234 The European Commission introduced Intelligent Speed Adaptation (ISA) 235 combining ITS “ speed alert” technologies to au tomatically adjust speed limits depending on traffic conditions . NHTSA has initiated the rulemaking process for speed limiter regulations in the United States. 236 2.5.1.2 Benefits The FMCSA noted the European Commission (EC) multiple benefits of speed limiters: “... l ower fuel consumption (from 3 percent to 11 %) , lower maintenance costs (tires, brakes, and engine), increased road safety (fewer casualties), more relaxed driving and lower insurance premiums as a consequence of less accidents .” The negative effects noted were: “...decreased road safety when performing an overtaking maneuver as overtaking another vehicle takes relatively longer . An indirect effect is that the long 229 Purchase, E. 2011. Trucking Speed Governors: PA Semi Accident Lawyers on NHTSA Study www.yourerieaccidentlawyers.com/blog/2011/09/trucking - speed - governors - pa - semi - accident - lawyers - on - nhtsa study.shtml 230 Trucker News Services. 2012. Speed limiter report: Trucks with devices had 50% lower ‘speed - limiter relevant’ crash rate www.thetrucker.com/News/Stories/2012/3/27/SpeedlimiterreportTruckswit hdeviceshad50lowerspeed limiterrelevantcrashrate.aspx 231 Road Safe America. 2012. The Problem: Physics www.roadsafeamerica.org/docs/RSASpeedLimiterWhitePaper_0039.pdf 232 Patton, O. 2011. NHTSA clears path for speed - limiter proposal www.truckinginfo.com/news/news detail.asp?news_id=72581 233 Summary Report - Assessment of a Heavy Truck Speed L imiter Requirement in Canada, TP14808 www.tc.gc.ca/eng/roadsafety/tp - tp14808 - menu - 370.htm 234 FMCSA. 2008. CTBSSP SYNTHESIS 16 Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses A Synthesis of Safety Practice http://onlinepubs.trb.org/ onlinepubs/ctbssp/ctbssp_syn_16.pdf 235 http://ec.europa.eu/transport/road_safety/specialist/knowl edge/esave/esafety_measures_known_safety_effects/inte lligent_speed_adaptation_isa.htm 236 See www.gpo.gov/fdsys/pkg/FR - 2011 - 01 - 03/html/2010 - 33057.htm56 overtaking maneuvers of vehicles fitted with speed limitation devices have the effect of reducin g the average speed of other road users .” The EC report concluded overall that:

“

It is clear that the known effects of speed limitation devices are generally very positive for drivers, for companies, for society and for the environment . The negative aspe cts are small and avoidable: if all the speed limitation devices were set accurately to the same speed, there would be less need for overtaking .” 237 According to the EPA SmartWay Partnership and the Truck Maintenance Council, reducing highway speed by 5 mile s per hour reduces fuel use and greenhouse gas emissions by about 7 percent while extending the life of a truck’s engine, tire treads, and brakes . Decreasing MD/HDV speed by one mile per hour would increase the FE by about 0.1 miles per gallon. 238 According to an American Transportation Research Institute survey of U.S. trucking fleets, the second most common intended goal of fleets that choose to implement speed limiters is reduction of crashes. 239 2.5.1.3 Safety Considerations Approximately 4,000 people die annually in multi - vehicle crashes involving large trucks, of which 98 percent are the occupants of passenger vehicles, motorcyclists, bicyclists, or pedestrians . This represents over 20 percent of all multi - vehicle crash deaths in the United States According to a r ecent FMCSA study, 240 approximately 15 percent of all truck crashes were identified as related to excessive speed. 241 The speed limiter - relevant crash rate 242 for trucks without speed limiters was 5 crashes per 100 trucks/year, compared to much lower 1.4 per 10 0 trucks/year crash rate for trucks equipped with speed limiters . The study showed that the overall crash rates for trucks without speed limiters were higher than for trucks with speed limiters, namely 16.4 versus 11 crashes per 100 trucks/year . “Results f rom multiple analyses indicated a profound safety benefit for trucks equipped with an active speed limiter,” the report concluded . These findings are consistent with reports from countries in which speed limiters have been mandated . Road Safe America repo rted that fatal commercial truck accident rates in those

237 FMCSA. 2008. CTBSSP SYNTHESIS 16 Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses A Synthesis of Safety Practice http://onlinepubs.trb.org/onlinepubs/ctbssp/ctbssp_syn_16.pdf 238 See NHTSA Oct 2010 study “Factors and Considerations for Establishing a Fuel Efficiency Regulatory Program for Commercial Medium - and Heavy - Duty Vehicles” at www.nhtsa.gov/staticfiles/rulemaking/pdf/cafe/NHTSA_Study_Trucks.pdf 239 American Transportation Research Institute. 2011. Predicting Truck Crash Involvement: A 2011 Update www.atri - online.org/research/results/ATRI_Crash_Predictor_One_Pg_Summary_Apr_2011.pdf 240 See FMCSA, march 21012, “Research on the Safety Im pacts of Speed limiter Devices on Commercial Motor Vehicles - Phase II” at www.fmcsa.dot.gov/facts - research/research - technology/report/Speed - Limiters.pdf 241 Trucker News Services. 2012. Speed limiter report: Trucks with devices had 50% lower ‘speed - limiter relevant’ crash ra te www.thetrucker.com/News/Stories/2012/3/27/SpeedlimiterreportTruckswithdeviceshad50lowerspeed limiterrelevant crashrate.aspx 242 Assessment of whether a crash was speed limiter - relevant was based on four types of information in the dataset used for the study: speed limit where the crash occurred, crash type (e.g., rear - end truck striking), contributing factor(s) i n the crash (used to exclude crashes; e.g., weather - related), and crash narrative.57 countries are lower than those in the United States. 243 In the UK, all articulated heavy - goods vehicles were speed limited after 1993 and the accident involvement rate for that vehicle class fell from 40 per hundred million vehicle kms in 1993 to 30 in 2005

— a 26 percent decrease. 244 Moreover, the heavy goods vehicles involvement in fatal crashes per 100,000,000 km has dropped to 1.1 in 2005 from 3.1 in 1990, a reduction of 65 percent. 245 A large truck tr aveling 75 mph requires approximately one - third more distance to stop compared with a truck traveling 65 mph. 246 Speed also exacerbates the size and weight differences between large trucks and passenger vehicles, leading to more severe crashes. ABF Freight System Inc. credits slower speeds with strengthening safety performance, although the exact benefit is impossible to calculate. 247 JB Hunt Transport stated that speed limiters will create a speed differential on the highway, but that the risk from that diff erential is outweighed by the risk of speeding . Schneider National reported that before there were universal speed limiters in its fleet, trucks without speed limiters accounted for 40 percent of collisions while traveling only 17 percent of the route mile s. 248 An analysis of nearly 19,000 truck crashes in Kansas found that 73 percent had contributory causes related to the truck driver . The top five contributors to truck crashes were: failing to give enough attention to the task, speeding, failing to yield th e right of way, improper lane changes and following another vehicle too closely . Additionally, researchers found that more truck crashes happened in locations with a high speed limit. 249 Similarly, in the FMCSA LTCCS “traveling too fast for conditions” was t he most frequently cited factor in crashes where trucks were assigned the critical reason for the crash. 250 Note that this may be due to lack of driver training rather than the presence or use of speed limiters. Data from the FARS for 2005 analyzed by the I IHS showed that an estimated 328 fatal crashes involved drivers of large trucks who were speeding, resulting in 374 deaths . About 24 percent of drivers of large trucks involved in fatal crashes in 2005 had at least one speeding conviction

243 Road Safe America, 2009. RSA Speed Limiter White Paper www.roadsafeamerica.org/doc s/RSASpeedLimiterWhitePaper_0039.pdf 244 FMCSA. 2008. CTBSSP SYNTHESIS 16 Safety Impa cts of Speed Limiter Device Installations on Commercial Trucks and Buses A Synthesis of Safety Practice http://onlinepubs.trb.org/onlinepubs/ctbssp/ctbssp_syn_16.pdf 245 Road Safe A merica. 2012. The Problem: Physics www.roadsafeamerica.org/docs/RSASpeedLimiterWhitePaper_0039.pdf 246 McCartt, A. T. 2007. IIHS Letter re: Motor Vehicle and Carrier Safety Standards; Devices to Limit the Speed of Certain Trucks Request for Comments; Docket No. NHTSA - 2007 - 26851 www.iihs.org/laws/comments/pdf/nhtsa_fmcsa_ds_atm_032707.pdf 247 Insurance Institute for Highway Safety. 2010. Speed Limiters in Trucks Would Serve 2 Purposes www.iihs.org/externaldat a/srdata/docs/sr4508.pdf 248 Patton, O. 2011. NHTSA clears path for speed - limiter proposal www.truckinginfo.com/news/news detail.asp?news_id=72581 249 Whistler, D. 2012. Researchers sift through crash statistics http://fleetowner.com/safety/researchers - sift - through crash - statistics? 250 FMCSA. 2007a. Large Truck Crash Causation Study http://ai.fmcsa.dot.gov/ltccs/default.asp58 within the past 3 years; this compared with 19 percent of passenger vehicle drivers involved in fatal crashes due to speeding. 251 A NHTSA 1991 report stated that the potential crash reductions from truck speed limiters were not sufficient to justify mandating them, since the y would have little effect on speeds or crash likelihood below the set maximum speed. 252 The Owner Operator Independent Drivers Association (OOIDA) cited this document in a 2007 opposing position statement. 253 OOIDA also has expressed the concern that when th ere is a speed differential between trucks and passenger cars, this increases the rate of lane changes and sudden braking events, and in turn increases potential for car

– truck crashes . However, a number of reports have found that speed limiters actually re duce speed variability and reduce lane change and deceleration maneuvers. 254 Europe’s experience with speed limiters that cap truck speeds at a speed substantially lower than the average speed of passenger vehicles also suggests no degradation in safety . H owever, since the 1995 repeal of the national maximum speed limit, which was in effect at the time of the previous NHTSA conclusion, there have been widespread increases in speed limits and in average travel speeds. 255 In 2009, the American Trucking Associa tion Safety Task Force endorsed electronically speed limiting all Class 7 and 8 trucks and setting a national 65 mph speed limit for all motor vehicles. 256 On January 3, 2011, NHTSA published a notice granting petitions for rulemaking from American Truckin g Association (ATA), Road Safe America, and nine major motor carriers. The notice announced that the agency would initiate the rulemaking process with a notice of proposed rulemaking (NPRM) on speed limiters for certain heavy trucks. FMCSA sponsored a Tra nsportation Research Board (TRB) study on “Commercial Truck and Bus Safety Synthesis Program (CTBSSP),” which assessed the safety impacts of speed limiter

251 McCartt, A. T. 2007. IIHS Letter re: Motor Vehicle and Carrier Safety Standards; Devices to Limit the Speed of Certain Trucks Request for Comments; Docket No. NHTSA - 2007 - 2685 1 www.iihs.org/laws/comments/pdf/nhtsa_fmcsa_ds_atm_032707.pdf 252 See “Commercial Motor Vehicle Speed Control Devices, 1991, Report No. DOT HS 807 725. It was supportive of fleet applications of speed monitoring and speed limiting devices, but concluded that, because of the small target size, there was not sufficient justification to require the application of speed limiting devices at that time. 253 Johnston, J. 2007. Comments of the owner - operator independent drivers association, inc in response to notice and request for comments Motor Vehi cle and Carrier Safety Standards [Docket No. NHTSA - 2007 - 26851] www.ooida.com/Issues&Actions/Regulatory/commentdocs/speed%20limiter%20 comments%20final%203 - 27 - 07.pdf 254 Varhelyi, A., & Makinen, T. 2000. The effects of in - car speed limiters: field studies http://partnet.vtt.fi/evaserve/evaserve_tool/aineisto/limiter.pdf , Toledo, H., Alb ert, G., and Hakkert, S., 2007. A Simulation - Based Evaluation of the Impact of Active Speed Limiters on Traffic Flow and Safety http://pubsindex.trb.org/view.aspx?id=801530 255 McCartt, A. T. 2007. IIHS Letter re: Motor Vehicle and Carrier Safety Standards; Devices to Limit the Speed of Certain Trucks Request for Comments; Docket No. NHTSA - 2007 - 26851 www.iihs.org/laws/comments/pd f/nhtsa_fmcsa_ds_atm_032707.pdf 256 American Trucking Association. 2009. Expanding ATA’s Safety Agenda Executive Summary www.trucking.org/A TA%20Docs/What%20We%20Do/Image%20and%20Outreach%20Programs/ART/Safety%20 Task%20Force%20Report.pdf59 device installations on commercial trucks and buses through a fleet survey. 257 The majority of U.S. fl eet managers (although based on a low survey response rate) indicated that speed limiters were either “successful” or “very successful” in reducing crashes . In operational terms, speed limiter users believed that limiters were either “successful” or “very successful” in reducing tire wear (44 %) and increasing fuel economy (76 %) . Almost 96 percent of respondents indicated speed limiters did not negatively affect safety or productivity. A recent FMCSA study on the efficacy of truck speed limiters in improvin g road safety 258 used truck crash data collected directly from truck fleets representing 138,000 trucks and over 15,000 crashes. The findings showed strong positive safety benefits for speed limiters . Trucks equipped with speed limiters had a significantly l ower overall crash rate (approximately 50 %) compared to those without, and a more than three - fold decrease in speed - limiter - relevant crash rate . A less comprehensive 2009 Transport Canada study of 400 power units across two fleets concurred that lower spee ds have resulted in an improved safety record . Based on the collision data reviewed, there was no evidence that speed limiters were contributing to the occurrence of collisions . In fact, there were no rear end collisions attributed to operating with a spee d limiter. 259 2.5.1.4 Findings and Conclusions Speed limiters on MD/HDVs have demonstrated significant fuel efficiency and safety benefits, while also reducing vehicle wear and tear and maintenance costs. 260 Case studies cited above from multiple adopting countrie s and from U.S. truck fleets indicate net positive safety benefits from broad adoption of this FE technology . Speed limiters appear to provide a consistent and effective means to maintain lower truck speeds, save fuel, and improve road safety. 2.5.2 Idle Reducti on Idle reduction technologies allow vehicle operators to refrain from long - duration idling of the main propulsion engine by using one of several alternative technology options. 261 An idle reduction device may be either installed on board a vehicle or at a wayside station to provide auxiliary power services (e.g., heat, air conditioning, and/or electricity) instead of the main drive engine, while the vehicle is parked or stationary . On - board idle reduction technologies include: • automatic start - stop, which s huts down the motor when the vehicle is stationary and starts it again once power is needed; • direct - fired heaters, which are small, lightweight heaters that burn fuel from the main engine fuel supply; and

257 FMCSA. 2008. CTBSSP SYNTHESIS 16 Safety Impacts of Speed Limiter Device Installations on Commercial Trucks and Buses A Synthesis of Safety Practice http://onlinep ubs.trb.org/onlinepubs/ctbssp/ctbssp_syn_16.pdf 258 FMCSA. 2012b. Research on the Safety I mpacts of Speed Limiter Device Installations on Commercial Motor Vehicles: Phase II www.fmcsa.dot.gov/facts - research/research - technology/report/Speed - Limit ers.pdf 259 Transport Canada. 2009b. Summary Report - Assessment of a Heavy Truck Speed Limiter Requirement in Canada www.tc.gc.ca/eng/roadsafety/tp - tp14808 - menu - 370.htm 260 See IIHS Status Report, Aug.21, 2010 “Speed limiters in trucks would serve two purposes” at www.iihs .org/externaldata/srdata/docs/sr4508.pdf 261 See EPA SmartWay verified idle Reduction options at www.epa.gov/smartway/technology/idling.htm60 • Auxiliary Power Units (APUs), which are small die sel engines that are installed on the truck to provide air conditioning, heat, and electrical power to run accessories like lights, on - board equipment, and appliances. Electrification can also provide the operator with climate control and auxiliary power without idling. This additional power may be delivered by on - board equipment (e.g., generator sets - GS, power inverters, solar panels, thermal storage systems - TSS), and/or off - board equipment (e.g., shore power at truck stops). 2.5.2.1 Penetration/Adoption The Nort h American Council for Freight Efficiency (NACFE) 2012 benchmarking study of anti idling technology penetration 262 found only a modest (less than 10 %) adoption rate for anti idling technologies by the truck fleets surveyed . Penetration of anti - idling devices has been driven both by economic payoff from cumulative fuel savings, as well as by compliance with anti - idling pollution laws 263 in 46 jurisdictions in 31 State s . These laws carry fines ranging from $100 - $25,000 per violation, and in some State s, repeat offenders may be jailed. 264 A wide range of truck OEMs, drivetrain suppliers, and integrators are offering trucks with built - in idle reduction systems, including Eaton, Altec, and Freightliner. 265 Anti - idling systems offer a good opportunity for petroleum an d emissions reductions in heavy duty vehicles

— particularly vocational vehicles, as well as for long - haul routes . Common idling situations occur at worksites where power from the main engine of a vocational truck is needed to operate equipment such as an ae rial lift, and when delivery vehicles stop for loading and unloading . Long - haul trucks idle for cab comfort during mandatory driver rest periods . Work truck fleets, such as Verizon, are implementing idle reduction solutions that operate the aerial using el ectric power, turning on the engine only when the energy storage system runs low. 266 2.5.2.2 Benefits Class 7 and 8 trucks alone consume over a billion gallons of diesel fuel per year when idling . Adoption of anti - idling options helped the eight study fleets surveye d by NACFE to lower their annual per truck fuel expense by an average of $4,500. 267 , 268 An Argonne National Laboratory analysis found that an idling model year 2001 truck uses 0.77 gal/hour for heating and 0.98

262 NACFE 2012 Anti - Idling Study http://nacfe.org/wp - content/uploads/2012/07/NACFE - 2012 - Anti - Idling - Study 062812.pdf 263 See CARB HDV idle reduction requirements at www.arb.ca.gov/msprog/truck - idling/truck - idling.htm 264 Cascade Sierra Solutions. 2 011. Shorepower Truck Electrification Project www.the - s tep - project.org/green answers/fleet - managers/ 265 TruckingInfo. 2012. Eaton enhances hybrid drive system for faster payback www.truckinginfo.com/n ews/news detail.asp?news_id=77134 , Freightliner. 2012. Freightliner hybrid trucks www.cleanandgreenvehicles.com/pdfs/M2eHybrid - Brochure.pdf , Altec Industries. 2012. Altec Green Fleet www.altec.com/green - fleet.php 266 Beegle, B. 2012. Worksite idle reduction www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26496 267 North American Council for Freight Efficiency. 2012b. 2012 Anti - Idling Study http://nacfe.org/wp content/uploads/2 012/07/NACFE - 2012 - Anti - Idling - Study - 062812.pdf 268 Ibid.61 gal/hour for cooling . In comparison, a direct - f ired heater only uses 0.06 gal; a storage air conditioner uses 0.2 gal; an APU uses 0.23 gal; and an electrified parking space uses between 1.7 and 2.4 kWh (between $1.00 and $2.45 per hour, well below the cost of diesel fuel consumed by idling). 269 Any tru ck or bus that idles 20 hours or more per week is projected to realize payback and return on investment within five years from implementing any of the idle reduction technologies. 270 2.5.2.3 Safety Considerations There were no safety incidents relating to the use of automatic start - stop, APUs, electrified parking spaces, or other idle reduction technologies identified in the literature . In comparison, potential safety benefits associated with idle reduction equipment adoption appear to be indirect, relating to driv er in - cab air quality health impacts, and to better sleep quality . Using either electrified parking space power or an auxiliary power unit for air conditioning improves in - cab air quality for nitrogen oxide (NOx), carbon monoxide (CO), particulate matter ( PM) and total hydrocarbons compared to an idling vehicle . Idling emissions can contribute to premature mortality, bronchitis (chronic and acute), hospital admissions, respiratory symptoms (upper and lower), cancer, asthma attacks, work loss days, and minor restricted activity days. 271 Given that up to one - third of drivers suffer from sleep apnea and many require continuous positive airway pressure machines in their cabs, improving conditions for sleep could reduce operator fatigue and thus reduce the potenti al for crashes due to sleeplessness. 272 2.5.2.4 Findings and Conclusions Idle reduction technologies can provide significant FE benefits to MD/HDV fleets, particularly for high - idling applications such as vocational and delivery vehicles, and long - haul sleeper tr actor cabs . When used in work trucks and delivery vehicles, these FE technologies also lead to a significant reduction in point source emissions of criteria pollutants in urban locations, where human exposure is high . Further research is needed to quantif y the safety benefits of idle reduction relating to improved in - cab air quality and potentially improved operator sleep, and any related effect on maintaining hours of service safety. This literature review did not identify any safety disbenefits of anti - i dling technologies. 2.6 Longer Combination Vehicles Longer combination vehicles (LCV) allow trucks to improve efficiency and save fuel by hauling more freight in a single load by pulling multiple trailers per tractor, thereby making fewer trips and reducing th e vehicle miles travelled. There are three common types: Rocky Mountain
269 Gaines, L. 2008. Which Idlin g Reduction Technologies Are the Best? www.transportation.anl.gov/pdfs/EE/533.pdf 270 Ibid. 271 DOE EERE. 2012b. Idle Reduction Research and Development www.afdc.energy.gov/afdc/vehicles/idle_reduction_research.html 272 Cascade Sierra S olutions. 2011. Shorepower Truck Electrification Project www.the - step - project.org/green answers/fleet - managers/62 Doubles, Turnpike Doubles, and Triple Trailers. 273 (See Figure 5 - 4 for the corresponding FHWA classification graphic. 274 ) 2.6.1 Penetration/Adoption LCVs have operated in 19 American State s for a number of decades, and Canada for several decades. LCVs are suited to light, bulky freight as their maximum allowable weight is no greater than other tractor - trailers currently in operation. The Surface Transportation Assistance Act (STAA) of 1982 provi ded for the unrestricted use of two - trailer combinations with two 28 - foot to 28.5 - foot trailers on the National Network (NN). 275 The National Truck Network (NTN) comprises 209,000 miles of highways that can accommodate large trucks, including the 47,000 mile Interstate Highway System . Some States allow LCVs with greater lengths or different tractor - semitrailer combinations, but most do not . LCVs are primarily allowed in Western States but are also permitted on some turnpikes, for example in New York and Mass achusetts. 276 For example, LCVs currently operate in 16 State s west of the Mississippi River and on turnpikes in 5 State s east of the Mississippi River . Among the State s that do allow LCVs, 11 allow operation of triples, 8 allow triples with permits, and 8 allow Rocky Mountain Doubles. Only 3 State s allow operation of LCVs without restrictions. 277 Of the eight major fleets surveyed by NACFE regarding LCV adoption, only one has begun to use double or triple trailers between 2003 and 2011. 278 2.6.2 Benefits Each LCV uses about one - third less fuel and emits one - third fewer greenhouse gas emissions than two tractor - trailers that would carry the same amount of freight. 279 LCVs introduce an increase of cargo - carrying capacity of 30 percent to 100 percent per driver . This re sults in fewer truck trips and fewer miles driven. 280 Fewer trucks on the road would also reduce congestion and improve safety . If freight that is currently moved by railroad is shifted to LCVs due to lower cost, the above benefits could decrease . However, the existence or extent of mode shifting and cross price elasticity has not been well studied.

273 DOE EERE. 2006. Fact #411: February 13, 2006 States that Allow Longer Combination Vehicles www1.eere.energy.gov/vehiclesandfuels/facts/2006_fcvt_fotw411.html 274 See original FHWA graphic at www.fhwa.dot.go v/policy/otps/truck/wusr/fig02_2.gif 275 The National Network consists of the Interstate System and routes designated by the FHWA in consultation with the States. 276 Ibid. 277 EPA. 2011a. EPA Smartway Longer Combination Vehicle Factsheet www.epa.gov/smartway/documents/partnership/trucks/partnership/techsheets - truck/EPA420F10 - 053.pdf 278 North American Council for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study http://nacfe.org/ 279 British Columbia Ministry of Transportation and Infrastructure. 2011. L ong Combination Vehicles Program www.th.gov.bc.ca/cvse/lcv/faqs.htm 280 California Department of Transportation. 2009. Longer Combination Veh icles www.dot.ca.gov/hq/traffops/trucks/exemptions/lcvs.htm63 2.6.3 Safety Considerations The safety of freight moving on highways and roadways is a combination of many factors, including exposure due to vehicle miles traveled, vehicle performance characteristics, driver fatigue and capability, enforcement, roadway design, road conditions, motor carrier management, and vehicle condition and maintenance . It is difficult to isolate the impact of truck size and weight (TS&W) among t hese factors. LCVs are allowed to operate on certain interstate and State highways in only 19 U.S. State s primarily due to concerns over safety and potential infrastructure damage and maintenance costs. 281 An advocacy organization, OOIDA, 282 has raised safet y concerns about LCVs, including the off - tracking of rear wheels when turning due to rearward amplification, 283 the incompatibility of LCVs with the turning radii of existing interchanges and intersections, their ability to maintain speed on inclines, and th eir potentially slower acceleration and braking in traffic . A related LCV hazard scenario and the references it is based on is discussed in detail in Chapter 5.2.5. Statistics on LCV crashes are difficult to obtain because of the low number of vehicles an d limited areas allowing them (See Section 6.6 and Figure 6 - 1) . It is known that triple trailers tend to experience rearward amplification and can leave the lane they are traveling in, although this can be lessened by advanced connector types or with advan ced active steer correction technology. Triples also require more passing length, spray more rain and snow, and have a history of being underpowered while climbing steep grades. 284 Heavier truck traffic can deteriorate pavement structures at an accelerated rate, and serious roadway defects can subsequently lead to crashes . One combination vehicle pass may cause wear equivalent to 2,000 to 3,000 cars . Excess pavement damage from LCVs is dependent on whether the increase in vehicle weight is distributed across a sufficiently increased number of axles. 285 In Canada, LCVs are no heavier than current tractor - trailers, yet they generally have more axles and tires to grip the road and are equipped with enhanced braking systems. Their stopping ability is generally sup erior to other tractor - trailers and their road damage should be no greater than current tractor - trailers . A number of Canadian reports suggest that collision rates for LCVs in Canada are relatively low, given the numerous restrictions of operation. 286 , 287 A 2005 study by the Canada Safety Council found that overall there is little difference in crash rates between LCVs and other trucks when operated under similar conditions of weather, road, and driver 281 Adams, T., Kleinmaier, D., Marach, A., Helfrich, G., Levine , J., & Bittner, J. 2012. Longer Combination Vehicles: An Estimation of their Benefits and Public Perception of Their Use www.wistrans.org/cfire/.../CFIRE_05 - 01_Final_Report.pdf 282 Owner - Operator Independent Drivers Associati on. 2005. Longer Combination Vehicles (LCVs) www.ooida.com/OOIDA%20Foundation/Issues/LCVs.asp 283 Paul S. Fancher and Kenneth L. Campbell, Truck Size and Weight Study Phase I: Working Papers 1 and 2 combined: Vehicle Characteristics Affecting Safety. www.fhwa.dot.gov/reports/tswstudy/vehiclsaf.htm 284 California Commercial Driver handbook 2010 - 2011 at www.dmv.ca.gov/pubs/comlhdbk/comlhdbk.pdf 285 Ibid. 286 British Columbia Ministry of Transportation and Infrastructure. 2011. Long Combination Vehicles Program www.th.gov.bc.ca/cvse/lcv/faqs.htm 287 Ibid.64 experience levels . However, LCVs reduce the vehicle miles traveled to move the same volume of freight, since each LCV typically carries as much freight as two single trailer trucks . Factoring in the reduced exposure and freight demand, the Safety Council concluded that LCVs have a safety record equivalent to sta ndard trucks. 288 This may be because of the strict controls in terms of routing, weather restrictions, and driving placed on them by the carriers and by the road authorities, and because the drivers must meet higher standards of skill and experience . Given the confounding factors and smaller sample size of LCVs, it is difficult to assess their relative safety performance. In 2010, the National Research Council reviewed and summarized a compendium of LCV studies from Canada, the United States, and Australia . A study published by the Canadian Journal of Civil Engineering reviewed accident rates in Alberta and concluded that from a collision rate perspective, LCVs as a group have better safety performance than other articulated trucks. Turnpike doubles, it repor ted, have the lowest collision rate of all articulated truck types, followed by Rocky Mountain doubles . Yet the collision rate for triple trailer combinations is higher than the collision rates for tractor semitrailers. 289 Previous studies of potential saf ety impacts of TS&W policy changes have relied primarily on studies that compared crash rates of single - and multi - trailer combinations . However, most multi trailer combinations are STAA 290 short (maximum 28’ 6”) doubles that are comparable in length and wei ght to single - trailer combinations . While these doubles are less stable than standard single - trailer tractor - semitrailers, they perform better than tractor - semitrailers in terms of their static rollover threshold and offtracking . The various LCV configurat ions analyzed typically fall between the tractor - semitrailer and the STAA double in terms of stability and control properties . Yet they are longer and heavier than either of those standard vehicles and they have greater offtracking . The opposite safety dif ferences along these two dimensions are occluded in aggregate crash rate studies, making it difficult to compare the relative safety performance of different LCV configurations. 291 The literature review offers no clear consensus on the safety of LCV operati ons to date and efficiency implications of expanding them nationwide . Some studies found LCVs to be less safe in terms of fatal crashes, or when cars pass LCVs . Others concluded that LCVs are safer because of lower collision rates, or lower crash costs ver sus tractor semi - trailers . The lack of sufficient data and controls in these studies, as well as inconsistent study methodologies, may prevent a definitive safety evaluation of LCVs at this time. 292 T he Federal Highway Administration Office of Freight Manag ement issued in December 2012 a notice soliciting bids for a new study on specific areas of Federal truck size and weight TS&W limits, their operation, and their impact s,

288 Ibid. 289 Regehr, J,. Montufar, J., Rempel, G . 2008. Safety performance of longer combination vehicles relative to other articulated trucks www.nrcresea rchpress.com/doi/abs/10.1139/L08 - 109 290 Surface Transportation Assistance Act 291 FHWA. 2004. Western Uniformity Scenario Analysis: A Regional Truck Size and Weight Scenario Requested by the Western Governors' Association www.fhwa.dot.gov/policy/otps/truck/wusr/chap07.htm 292 Adams, T., Kleinmaier, D., Marach, A., Helfrich, G., Levine, J., & Bittner, J. 2012. Longer Combination Vehicles: An Estimation of their Benefits and Public Perception of Their Use www.wistrans.org/cfire/.../CFIRE_05 - 01_Final_Report.pdf65 responding to a mandate in the Moving Ahead for Progress in the 21st Century (MAP - 21) legislation. 293 Th is requirement to further study the issue was a compromise between proponents of allowing six - axle truck/trailer configurations to gross 97,000 pounds and opponents of any size or weight increases. 2.6.4 Literature Findings Based on references discussed above LCVs can result in significant fuel efficiency improvement of 30 percent over conventional tractor trailers, with proportional reductions in pollutant and greenhouse emissions . Due to a decrease in VMT per unit of cargo, reduced crashes wo uld also be expected . Whether these expected safety benefits are realized, could be influenced by whether, and to what extent, any rail cargo is diverted to LCVs . If this occurs, the benefits could be reduced. 294 Even assuming there is no significant frei ght rail diversion to the highway mode, it is still difficult to extrapolate the positive safety findings from studies conducted outside the United States to U.S. - wide LCV operations because the operating environments differ . Regulatory differences could a lso be expected to have a significant impact on the safety of LCV operations. 295 Potential LCV hazards (see Section 5.2.5), such as offtracking and rearward amplification of LCVs require further evaluation. Advanced rearward amplification - reducing bogies o r active steering correction systems may offer some safety mitigation . Operational restrictions, including strict route designations and strict driver training standards for LCVs, may also be required . Oversized and overweight LCVs may be good candidates f or the use of telematics systems that monitor and help ensure the safety performance of drivers. 2.7 Tire Technologies 2.7.1 T ire Pressure Monitoring Systems and Automatic Tire Inflation Systems Based on a representative study of hundreds of trucks, FMCSA determin ed that tire pressure is within 5 psi of proper pressure in only half of all truck tires. 296 In addition to programs of routine manual pressure checking and inflation procedures, a number of tire pressure monitoring systems (TPMS) and automatic tire inflati on systems (ATIS) can be installed onboard MD/HDVs . These systems report the tire pressures to the driver or issue an alert if tire pressure is below a set point . Furthermore, in - pavement tire pressure pads have become available for fleet terminals that me asure the tractor and trailer’s tire pressure as it drives over the device. 297

293 Se FHWA Talking Fr eight at www.fhwa.dot.gov/planning/freight_planning/talking_freight/nov282012transcript.cfm 294 FHWA. 2004. Western Uniformity Scenario Analysis: A Regional Truck Size and Weight Scenario Requested by the Western Governors' Association www.fhwa.dot.gov/policy/otps/truck/wusr/chap07.htm 295 Ibid. 296 Lockridge, D. 2010. FMCSA talks safety technology www.truckinginfo.com/news/news detail.asp?news_id=70422 297 North American C ouncil for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study http://nacfe.org/66 2.7.1.1 Penetration/Adoption According to NACFE, only automatic tire pressure inflation systems on trailers had significant adoption rates, with nearly 30 percent of the trailers in the eight surveyed fleets incorporating ATIS by 2011. 298 There does not seem to be a predominant tire FE technology or practice emerging, so NACFE is continuing annual tire pressure benchmarking surveys 299 of fleet adoption and FE gains . Most fleets still choose to manage correct tire pressure through routine manual maintenance rather than procuring systems that will monitor and inflate tires on their own. 300 Approximately only 5 percent of national truck fleets employ TPMS technology . The low penetration rate appe ars to be based on concerns of system reliability, maintenance costs, and initial system costs. 301 2.7.1.2 Benefits Correct tire inflation is important for achieving optimal fuel economy in commercial motor vehicles (CMVs) . Preliminary results from a FMCSA field o perational test with one truck fleet indicated a 1.8 percent increase in FE due to TPMS and found that the tires on non - equipped control trucks showed faster wear than those on TPMS trucks . The extra wear corresponded to one extra road call per year. 302 Ano ther FMCSA study of three different TPMS models recorded a fuel economy increase of 1.4 percent and positive ROI in less than one year . Tread wear improvements were measurable, especially on the drive tires . According to the study, some drivers who were in itially wary of the systems eventually asked management to equip entire fleets with TPMS and ATIS. 303 TPMS systems, whether on - board or terminal - based, greatly assist in a fleet’s ability to monitor, take action and continue to educate drivers and maintenanc e technicians on the importance of correct tire inflation for both FE gains and for safe stopping distance when braking . In combination with a telematic system, TPMS can also report tire pressures to a web portal and warn the fleet manager or dispatcher o f underinflated tires . One TPMS manufacturer claims that this extends the life of tires up to 20 percent. 304 NACFE studies reported that fleets adopting tire pressure inflation and monitoring systems for use on vehicles, using drive - over tire pressure measur ement mats or strictly requiring drivers to routinely check pressure saved $4,500 per year. 305

298 Ibid. 299 See http://nacfe.org/wp - content/uploads/2012/07/NACFE - 2012 - Tire - Pressure - Study - 062812.pdf 300 North American C ouncil for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study http://nacfe.org/ 301 Lockridge, D. 2010. FMCSA talks safety technology www.truck inginfo.com/news/news detail.asp?news_id=70422 302 Ibid. 303 Park, J. 2012. DOT study proves ROI on tire inflat ion and pressure monitoring systems www.truckinginfo.com/news/news - detail.asp?news_id=76201 304 WABCO. Integrated Vehicle Tire Pressure Monitoring (IVTM) www.wabco - auto.com/ivtm 305 North American Council for Freight Efficiency. 2012c. 2012 Tire Pressure Study http://nacfe.org/wp content/uploads/2012/07/NACFE - 2012 - Tire - Pressure - Study - 062812.pdf67 2.7.1.3 Safety Considerations Tire under - inflation results in irregular tire wear, which can reduce the ability of tread to grip the road in adverse conditions. 306 Currently , NHTSA requires TPMS for proper tire inflation for light duty cars and trucks in view of safety benefits. 307 A concern with some automatic tire inflation systems noted in the NACFE reference cited is that a driver may be over reliant on TPMS/ATIS and conti nue to drive on a flat tire, expecting it to self - inflate, only to have a blowout later if the ATIS fails. 308 As with any new technology, driver education is required to understand the limitations of the technology. 2.7.1.4 Literature Findings A tire can lose up t o half of its air pressure and still not appear to be flat, so either regular checks by the driver, or automatic systems such as TPMS/ATIS, are critical for both vehicle safety and for optimal fuel efficiency . It is not clear from the available literature whether such automatic systems for MD/HDVs lead to safer vehicle operations, versus diligent visual checking procedures . However, there is also no evidence to indicate that TPMS/ATIS adoption leads to lower safety performance . Given that a wide range of ti re checking diligence may be expected across fleets and drivers, automatic systems appear likely to raise the lowest common denominator of diligence, and therefore operational safety . 2.7.2 Single Wide Tires Although heavy and medium trucks still most commonly use double tires at each wheel site, over the past decade major tire suppliers have begun to offer single wide base

– or “super single”

– tires for MD/HDVs . With single wide tires, only one tire is installed per wheel site instead of two (Figure 2 - 11); mea ning an 18 - wheeler becomes a 10 - wheeler . This design change is intended to improve fuel efficiency through a combination of decreased rolling resistance, lower aerodynamic drag, and reduc ed weight.

Figure 2 - 11 : Single Wide Base Tires Replacing Duals at Each Wheel Site 309

306 HCI Co rporation. 2011. Tire - SafeGuard www.tiresafeguard.com/ 307 See Safercar.gov TPMS postings at www.safercar.gov/Vehicle+Shoppers/Tire s/Tires+Rating/TPMS 308 North American Council for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study http://nacfe.org/ 309 North American Council for Freight Efficiency. 2010. Executive Report

– Wide Base Tires68 2.7.2.1 Penetration/Adoption More than two decades ago, single wide tires were seen as an alternative to the conventional dual truck tire assembly that had been the industry standard since its introdu ction in the early 20 th century . Numerous fleets and owner operators have adopted this technology. 310 Two of the eight major truck fleets surveyed by NACFE have exclusively adopted single wide tires, driven by weight reduction and fuel economy goals. 311 One fleet surveyed by NACFE had no plans to adopt over concerns about the initial cost and the break even period . All surveyed fleets believed that tire and wheel availability and other issues that prevented widespread single wide tire adoption no longer exis t . These fleets indicated that pressure from heavier tractors  due to new EPA emissions equipment

 and from denser loads

 led them to consider weight - saving measures, including wide - base tires. 2.7.2.2 Benefits Studies indicate that single wide tires may yield fuel savings of 2 - 6 percent, as a result of reduced aerodynamic drag, rolling resistance, and weight reduction. 312 , 313 Single wide tires were also reported to improve vehicle stability and handling, especially for tanker trailers by allowing the tank to be mounted lower. 314 A lower center of gravity should reduce the risk of vehicle rollover . The total weight savings for a typical combination truck using single wide base tires on its drive and trailer axle ranges from 800 to 1,000 pounds. The weight savings reduce fuel consumption or increase cargo capacity for trucks that are weight - limited . Single wide tires may offer other benefits in combination with improved truck stability. 315 Using single wide tires, there are also fewer tires and no hard - to - reach inner tires . Most uneven tire wear occurs because one dual has less air in it than another. That problem is eliminated with singles. 316 Increased brake life is also a possible benefit of using single wide tires . Depending on axle width and wheel offset, more of the bra ke drum is exposed to open air, allowing the drum and shoe to stay cooler, with claimed benefits of up to an extra 20,000 miles of brake life per tractor . http://nacfe.org/wp - content/uploads/2010/12/NACFE - ER - 1002 - Wide - Base - Tires - Dec - 2010.pdf 310 Ibid. 311 No rth American Council for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study at www.greenfreightandlogistics.org/news/2011 - fleet - fuel - efficiency - benchmark - study/ / 312 Salari, K. 2012. DOE’s Effort to Reduce Truck Aerodynamic Drag through Joint Experiments and Computations www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/veh_sys_sim/vss006_salari_2012_o.pdf 313 North American Council for Freight Efficiency. 2 010. Executive Report

– Wide Base Tires http://nacfe.org/wp - content/uploads/2010/12/NACFE - ER - 1002 - Wide - Base - Tires - Dec - 2010.pdf 314 EPA. Smartway: a glance at clean freight strategies: single wide based tires at www. epa.gov/smartway/forpartners/documents/trucks/techsheets - truck/EPA - 420 - F10 - 041.pdf 315 EPA. 2012. Low Rolling Resistance Tires A Glance at Cl ean Freight Strategies www.epa.gov/smartway/documents/partnership/trucks/partnership/techsheets - truck/EPA - 420 - F10 - 041.pdf 316 Overdrive. 2012. Single - Minded www.ove rdriveonline.com/single - minded/69 2.7.2.3 Safety Considerations A potential safety concern is that drivers may lose control when a single wide tire blows out on the highway, since there is no remaining dual to shoulder the load on that wheel site. This appears unlikely to happen because most combination trucks have tandem axles, so they can still pull over to the shoulder if a wide base tire fai ls . The single wide tires also lower the vehicle’s center of gravity, so the vehicle may be less likely to lose control than one with dual wheels. 317 When a single wide tire fails, the vehicle is certainly down and cannot be “limped in” to the nearest point of service, as can be done with dual wheels. However, with the implementation of new CSA rules “limping in” may no longer be accepted practice. 318 Single tires eliminate the potential for the two tires on a dual wheel to have different pressures . Unequall y inflated dual wheel tires shift the load to the tire with higher pressure . This may not be visually apparent and therefore is likely to occur without the driver’s knowledge, increasing the probability of a blowout. 319 Fleets that have adopted single wide tires report that breakdowns with wide base tires occur less frequently because the driver can visually detect when they have a low tire and address the issue sooner than on a vehicle with dual wheels. 320 Testing by tire manufacturers and fleets suggests tha t traction of wide base tires is comparable to that of dual tires. 321 2.7.2.4 Findings and Conclusions Given advances in single wide tire design over the past decade, and in light of positive fuel efficiency gains and safety experience to date reported by NACFE and major fleet adopters, wide base tires were found to offer a straightforward and low - risk way to reduce weight and to improve the FE of MD/HDVs fleets by a significant 2 - 6 percent. 2.7.3 Low Rolling Resistance Tires Overcoming tire rolling resistance accounts for nearly 13 percent of the total energy required to keep a combination truck in motion. 322 Tire design plays a key role in determining the level of rolling resistance, and innovations in tire tread design have made it possible to decrease resistance . Whil e there have been indications that for some rugged duty cycles these lower rolling resistance tread designs may not provide sufficient traction, most long - haul highway based trucks have already adopted lower rolling resistance tires. 323

317 Ibid. 318 NACFE 2010 Wide base tires report at http://na cfe.org/wp - content/uploads/2010/12/NACFE - ER - 1002 - Wide Base - Tires - Dec - 2010.pdf 319 Overdrive . 2012. Single - Minded www.overdriveonline.com/single - minded/ 320 See ref 282 NACFE 2010 report 321 North American Council for Freight Efficiency. 2010. Executive Report

– Wide Base Tires http://nacfe.org/wp content/uploads/2010/12/NACFE - ER - 1002 - Wide - Base - Tires - Dec - 2010.pdf 322 EPA. 2011c. SmartWay Technology Program: Verified Low Rolling Resistance Tires www.epa.gov/smartway/tec hnology/tires.htm 323 Carbon War Room Research & Intelligence Group. 2012. Unlocking fuel - saving technologies in trucking and fleets70 2.7.3.1 Penetration/Adoptio n All eight fleets surveyed by NACFE, representing 75,000 tractors and 130,000 trailers, have adopted low rolling resistance tires. 324 The EPA references a test of LRR tires on 15 fleets that logged 57 million miles. 325 More extensively, all non - short - haul h eavy - duty tractors that pull 53 - foot or longer box - type trailers in California have been required to install LRR tires since 2010 following the adoption of an Air Resources Board greenhouse gas reduction regulation. 326 2.7.3.2 Benefits The EPA’s SmartWay Partnership states that the FE improvement due to LRR tires is 2 - 5 percent . SmartWay acknowledges that LRR tires may have slightly decreased tread life, but cites a manufacturer report that found the tires to wear at a rate comparable to conventional tires. 327 These improvements are achieved when verified low rolling resistance tires are installed on all of the axle positions of the tractor and trailer and when all tires are properly inflated according to the manufacturer's specifications. 328 2.7.3.3 Safety Considerations In a 2009 NHTSA study of low and standard rolling resistance tires for light - duty vehicles, the tire models tested were found to show a strong and significant relationship between lower rolling resistance and lower wet slide number (i.e., locked - tire wet tract ion coefficient). This may be significant to light - duty vehicles that are not equipped with anti - lock braking system (ABS), since the wet slide number relates most closely to locked - wheel emergency stops on wet road surfaces . For newer vehicles with ABS or electronic stability control systems, the tradeoff was predicted to be less significant. 329 However, it is important to note that ABS have been required by NHTSA on all trucks and buses since the 1997 - 1999 implementation timeframe. 330 A recent

http://carbonwarroom.com/sites/default/files/reports/Unlocking%20Fuel%20Saving%20Technologies%20in%20Tru cking%20and%20Fleets%20(Carbon% 20War%20Room).pdf 324 North American Council for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study http://nacfe.org/ 325 EPA. 2012. Low Rolling Resistance Tires A Glance at Clean Freight Strategies www.epa.gov/smartway/forpartners/documents/verified/420f12024.pdf 326 Californi a Air Resources Board. 2012. Heavy - Duty (Tractor - Trailer) Greenhouse Gas Regulation www.arb.ca.gov/cc/hdghg/hdghg.htm 327 EPA. 2012. Low Rolling Resistance Tires A Glance at Clean Freight Strategies www.epa.gov/smartway/ documents/partnership/trucks/partnership/techsheets - truck/EPA - 420 - F10 - 041.pdf 328 EPA. 2011c. SmartWay Technology Program: Verified Low Rolling Resistance Tires www.epa.gov/smartway/technolog y/tires.htm 329 Evans, L. R., MacIsaac, J. D., Harris, J. R., Yates, K., Dudek, W., Holmes, J., Popio, J., Rice, D., & Salaani, M. K. 2009. NHTSA Tire Fuel Efficiency Consumer Information Program Development: Phase 2

– Effects of Tire Rolling Resistance Levels on Traction, Treadwear, and Vehicle Fuel Economy www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle%20Research%20&%20Test%20Center%20%28VRTC%29/ca/Tires/8 11154.pdf 330 Jermakian, J.S. 2012. Crash avoidance poten tial of four large truck technologies. Accident Analysis and Prevention 49:338 - 46, at www.iihs.org/iihs/topics/t/crash - avoidance - technologies/qanda#ant ilock - brakes71 Transport Cana da study 331 of Class 8 long - haul trucks equipped with SmartWay - certified LRRs demonstrated safe traction performance in winter conditions, while increasing fuel economy and reducing emissions. 2.7.3.4 Findings and Conclusions Although safety trade - offs from lower t raction are theoretically possible, the literature search did not identify data on safety impacts of LRR tires in MD/HDVs, or reports of safety hazards from lower LRR road grip in snow, ice or wet conditions that could result in potential degraded handling or longer braking distance . The average age of Class 8 tractors, which stand to benefit the most from LRR tires, is approximately 9 years. 332 This means that LRR replacement tires would have to be installed to continue the FE benefits over the life of the vehicle . 2.8 Aerodynamic Components Aerodynamic technologies minimize drag and improve the airflow around a moving MD/HDV. Examples of aerodynamic technologies include gap fairings that reduce turbulence between the tractor and trailer, side skirts that minim ize wind under the truck body, and rear fairings that reduce turbulence and pressure drop at the rear of a trailer. Additionally, streamlined side mirrors, roof deflectors, cabin extenders, and other systems are available. The EPA SmartWay program has ver ified four categories of aerodynamic components through its fuel efficiency technology certification: 333 • Trailer Gap Reducer

— fairings attached to front of trailer • Trailer Boat Tail

— fairings attached to rear of trailer • Trailer End Fairing

— attached to underbo dy of trailer • Trailer Skirts

— fairings attached to sides of trailer underbody 2.8.1 Penetration/Adoption Eight major truck fleets, representing 75,000 tractors and 130,000 trailers, participated in a benchmarking technology adoption study led by NACFE from 2003 t o 2010 . The tractors studied drove over 3 billion miles in 2010, by which time all eight fleets had adopted most, if not all of the available tractor aerodynamic features, including bumpers, mirrors, roof fairings, chassis skirts, and minimized fifth wheel height. OEMs are now typically filling the gaps between bumpers and fenders. 334 Figure 2 - 12 illustrates the relative adoption rate of aero FE technologies, relative to other FE technologies discussed here.

331 www.tc.gc.ca/eng/mediaroom/releases - 2013 - h007e - 7042.htm and Packed snow performance of low rolling resistance class 8 heavy truck tires - Feb. 2013 Executive Su mmary at www.tc.gc.ca/eng/programs/environment etv - packed - snow - performance - eng - 2913.htm 332 Heavy - Duty Truck Fleet Ages as Carriers Seek Cost Savings. www.trustheart.com/news - bulletins/ltl - and - tl bulletins/91 - heavy - duty - truck - fleet - ages - as - carriers - seek - cost - savings 333 EPA. 2011b. SmartWay Technology Program: Verified Aerodynamic Technologies at www.epa.gov/smartway/forpartners/technology.htm 334 North American Council for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study / http://nacfe.org72 While aerodynamic improv ements for tractors are already being widely adopted, aerodynamic devices for trailers are not yet as well used . In part, this is because most trailer aerodynamic devices were not widely available or adopted until recently . For instance, boat tails on the backs of trailers have only been available since 2007 . Trailer skirts have been quickly adopted in the past 3 years, accelerated both by a California Air Resources Board (CARB) requirement and by the increased price of fuel

— given that trailer skirts offer greater FE benefit than other component types . In December 2008, CARB adopted a regulation to reduce greenhouse gas emissions from 53 - foot or longer box - type tractor - trailers . A combination of tractor and trailer aerodynamics and the use of low rolling res istance tires are mandated by the CARB regulation. 335 Although the NHTSA/EPA MY2014 - 18 regulation does not cover trailers, the adoption rate trends shown in Figure 2 - 12 suggest that the gap between tractor and trailer aerodynamics may narrow in the next few years.

Figure 2 - 12 : FE Technology Adoption Across Eight Major Fleets 336 A number of new concepts have recently emerged for trailer aerodynamic upgrades . For example, a device known as an undertray fairing m ay be substituted for the more prevalent truck skirts and boat tails . Competition of aero designs may accelerate aerodynamic devices adoption by long - haul truck fleets. 337

335 California Air Resources Board. 2012. Heavy - Duty (Tractor - Trailer) Greenhouse Gas Regulation www.arb.c a.gov/cc/hdghg/hdghg.htm 336 North American Council for Freight Efficiency. 2012a. 2011 Fleet Fuel Efficiency Benchmark Study http://nacfe.org/ 337 Ibid.73 For package delivery and utility trucks that operate in stop - start mode, or short rang es, aero devices add weight and may reduce fuel efficiency, although medium - duty trucks operating on highway - intensive duty cycles offer benefits and growth potential for aerodynamic upgrades. 338 2.8.2 Benefits According to a DOE modeling study and testing, aerody namic devices offer significant potential to improve the fuel efficiency of medium and heavy - duty trucks . Specifically, for a box - type tractor - trailer, the combination of a gap reducer, a trailer skirt, and a boat tail can yield 26 percent drag coefficient reduction . This corresponds to FE gains respectively of a: • gap reducer: 1 - 2 percent , • underbody skirt: 5 - 7 percent , and • boat tail: 4 - 7 percent . DOE indicates that a 12 percent reduction in fuel use from decreased aerodynamic drag would translate to about 3.2 billion gallons of diesel fuel saved per year and 28 million tons of CO2 emission reduction for a Class 8 tractor - trailer. Also that that additional FE reductions could result from combining aerodynamic upgrades with single wide tires. 339 The 2010 Nati onal Research Council (NRC) report estimated that the fuel efficiency improvement available today for trailer aerodynamics is 5.5 percent but concurs with the DOE analysis that the benefit can increase to 11.5 percent in just a few years. 340 EPA stated that using fairings can increase fuel efficiency by as much as a 15 percent when applied to an early model combination tractor - trailer truck and 3 - 11 percent when applied to a newer Class 8 truck in long haul highway type operation. 341 Manufacturers claim that using only one aerodynamic surface, such as a rounded air deflector, can increase fuel efficiency by up to 5 percent, reducing fuel use by about 80 gallons, thus saving over $100. The range of boat tails tested in another study, ranging from a 2 feet to 5 feet extension, were reported to reduce tractor - trailer fuel consumption between 4.7 percent and 7.3 percent, similar to the DOE figures. 342 According to the NACFE technology adoption study, large truck fleets have reported varying degrees of real world fu el economy performance gains from 2 percent to about 5 percent for aerodynamic devices. 343 338 Carbon War Room Research & Intelligence Group. 2012. Unlocking fuel - saving technologies i n trucking and fleets http://carbonwarroom.com/sites/default/files/reports/Unlocking%20F uel%20Saving%20Technologies%20in%20Tru cking%20and%20Fleets%20(Carbon%20War%20Room).pdf 339 Salari, K. 2012. DOE’s Effort to Reduce Truck Aerodynamic Drag through Joint Experiments and Computations www1.eere.energy.gov /vehiclesandfuels/pdfs/merit_review_2012/veh_sys_sim/vss006_salari_2012_o.pdf 340 National Research Council. 2012. Review of the 21st Century Truck Partnership, Second Report www.nap.edu/openbook.php?record_id=13288&page=R1 341 EPA. 2011b. SmartWay Technology Program: Verified Aerodynamic Technologies www.epa.gov/smartway/technology/aerodynamics.htm 342 Patten, J., Poole, G., Mayda, W., & Wall, A. 2010. Trailer Boat Tail Aerodynamic and Collision Study www.tc.gc.ca/eng/roadsafety/safevehicl es - motorcarriers - environment - boat - tails - 1307.htm 343 California Air Resources Board. 2012. Heavy - Duty (Tractor - Trailer) Greenhouse Gas Regulation www.arb.c a.gov/cc/hdghg/hdghg.htm74 2.8.3 Safety Considerations Many boat tail configurations that provide high drag reduction possibilities include boat tail material that is as low as 44 inches from the grou nd, which could cause a vehicle to strike the boat tail before or instead of the rear impact guard . For many configurations, this material is sufficiently short that the collisions are mostly grille or hood strikes. 344 This Transport Canada aerodynamics air flow analysis and collision estimation of boat tails was based on scale models and wind tunnel testing . It concluded that in truck - truck collisions, class 4 - 6 straight trucks with cab - over engine designs have the greatest potential for occupant injury . If a cab - over engine driver rear - ends a truck equipped with boat tails, the horizontal boat tail structural member could protrude through the windshield. 345 The data required to quantify these strikes were not included in the report, however, and the report re commended further study to expose cab - over engine vehicle populations in the analysis . No specific windshield strike cases were found in literature . The Transport Canada study identified tradeoffs between optimal FE gain and minimizing the risk of other ve hicles' collision with the boat tail. 346 Even though the bottom panel of boat tail configurations provides up to 20 percent of the overall aerodynamic benefit, the study concluded that it could result in safety hazard in colder climates . Ice and snow can pot entially accumulate on the bottom panel and later become dislodged, creating dangerous shedding conditions for cars behind the truck . Damage from road debris, or detachment of aerodynamic skirts and tails in normal vehicle operation are a potential safety issue for aerodynamic features, particularly for underbody devices . However, no reported incidents of aerodynamic component detachment or structural failure while en route could be found in the literature . T railer skirt developers have prioritized the des ign of components that are resilient against road damage . Various aerodynamic skirts have been in continuous use on MD/HDVs in European and certain Asian countries for over two decades, where regulatory and economic factors promote both fuel efficiency and the provision of vulnerable road user (VRU) underride protection. 347 Newer skirts are typically constructed of fiber - reinforced plastic and appear to resist damage when repeatedly impacted by curbs, loading dock ramps, railroad crossings, and snow (Figure 2 - 13). 348 Some designs have full - flex struts that allow them to bend up to 90 degrees rather than snap, as in older monolithic designs, and they weight as little as 190 pounds. 349 , 350 There is a relatively low impact on the vehicle weight

— approximately 0.25 p ercent of an 80,000 GVWR.

344 Patten, J., Poole, G., Mayda, W., & Wall, A. 2010. Trailer Boat Tail Aerodynamic and Collision Study www.tc.gc.ca/eng/roadsafety/safevehicles - motorcarriers - environment - boat - tai ls - 1307.htm www.tc.gc.ca/eng/roadsafety/safevehicles - motorcarriers - environment - boat - tails - 1307.htm 345 Ibid. 346 Ibid. 347 National Research Council. 2010a. Technologies and Approaches to Reducing the Fuel Consumption of MD/HD Vehicles www.nap.edu/openbook.php?record_id=12 845&page=R1 348 www.youtube.com/watch?v=PzGhXtJyIBU 349 Freight Wing Incorporated. 2011. Aeroflex www.freightwing.com/aeroflex.php 350 Green Big Truck. 2010. Laydon Composits Gets CARB Certified for Trailer Skirt Products http://greenbigtruck.com/2010/02/laydon - composits - gets - carb - certified - for - trailer - skirt - products/75 Figure 2 - 13 : Aerodynamic Trailer Skirt Survivability to Impacts 351 Aerodynamic features can provide both truck occupant and non - occupant safety benefits unrelated to reducing fuel c onsumption and greenhouse gas emissions . The safety benefit of skirts that also act as VRU sideguards in certain operating environments are discussed separately below. 2.8.3.1 Side Skirts There are various reports that side skirts and boat tails improve trailer - tr acking stability, especially in crosswinds . Additionally, skirts appear to significantly reduce road spray from trailer tires, improving visibility for nearby vehicles on the highway . One trailer skirt manufacturer, Laydon Composite, states that its device s are both damage resistant and comply with the European heavy truck sideguard regulation. 352 European Council Directive 89/297/EEC (ECD, 1989) mandates side under - ride protection on trucks over 3.5 tons to prevent pedestrians, bicycle riders, and motorcycl ists from falling and being crushed under the wheels of a moving vehicle. 353 Based on data from the European Union, the number of deaths and serious injuries for VRUs involved side - impact crashes with heavy vehicles has been reduced since the universal impl ementation of sideguards in 1986 in the United Kingdom 354 and on the Continent in 1989. 355 Side impacts comprise a large subset of VRU - truck fatalities. 356 In the United States , 55 percent of bicyclist fatalities and 29 percent of pedestrian fatalities involvin g tractor trailers in 2005 - 2009 followed initial point of impact with the right or left sides of the truck. 357 The

351 Freight Wing Incorporated. 2011. Aeroflex www.freightwing.com/aeroflex.php 352 National Research Council. 2010b. Technologies and Approaches to Reducing the Fuel Consumption of Medium - and Heavy - D uty Vehicles www.nap.edu/openbook.php?record_id=12845&page=R1 353 European Union. 1989. European Council Directive 89/297/EEC http://eur lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31989L0297:EN:HTML 354 UK Road Vehicles (Construction and Use) Regulations 1986. www.legislation.gov.uk/uksi/1986/1078/made 355 Patten, J. D., & Tabra, C. V. 2010. Side Guards for Trucks and Trailers Phase 1: Background Investigation www.safetrucks.ca/resources/National_Research_ Council_Truck_Side_Guard_Study_2010 - 03 - 01.pdf 356 Ibid. 357 N TSB, Safety Recommendations H - 14 - 001 through - 007, 2014. www.ntsb.gov/safety/safety - recs/RecLetters/H 14 - 001 - 007.pdf76 corresponding side - impact fractions of bicyclist and pedestrian fatalities involving single - unit trucks during 2005 - 2009 were 44 percent and 2 5 percent . 358 Sideguard devices that comply with the EU - directive have been correlated with a 61 percent bike fatality reduction in side collisions with heavy trucks in the United Kingdom following implementation on most of its truck fleet . Two examples of safety - driven truck side - guard adoption in the United States are the municipal truck fleets of Portland, Oregon, which performed the retrofits in 2008 359 , and Boston, MA, which fitted its municipal trucks in 2013. 360 An ordinance requiring the Washington, D.C . municipal fleet to be fitted with sideguards was enacted in 2008. 361 None of these safety - driven efforts has simultaneously considered impacts on vehicle fuel efficiency. It is unclear whether all U.S. models of aerodynamic side skirts would also provide comparable safety benefit for VRU under - ride protection . This question, as well as a comprehensive cost benefit analysis that jointly considers VRU safety and fuel efficiency benefits across different MD/HDV classes and operating environments, could benefi t from further study . Such a study could explore the effects on VRU safety and fuel consumption of a design that attempts to address both issues. If VRU under - ride protection were considered as a core function of the side skirt, the skirt’s impact resistan ce, geometry, and visibility would need to be considered in tandem with its fuel efficiency effects . This could mean minimizing gaps in coverage, increasing conspicuity, and ensuring a minimum lateral resistance to force, commensurate with the impact of a cyclist or pedestrian, or possibly of a motorcyclist , lower ground clearance, making the sideguard flush with the side of the truck body, and by extending the sideguard longitudinally. 362 2.8.4 Findings and Conclusions Aerodynamic technologies offer significant fuel savings in the 5 - 15 percent range for MD/HDVs, depending on how full a package is installed, and on the drive cycle of the vehicle . Maximum benefit will be realized for long - haul Class 8 trucks, as recognized in the EPA SmartWay program . While the li terature indicates that some users have concerns about damage to underbody fairings or skirts, there were no documented incidents of any safety - critical damage.

358 NTSB, Crashes Involving Single - Unit Trucks that Resul ted in Injuries and Deaths, 2013. www.ntsb.gov/safety/safety - studies/Documents/SS1301.pdf 359 City of Portland. 2007. Improving Bicycle Safety in Portland www.portlandonline.com/shared/cfm/image.cfm?id=191337 360 City of Boston Mayor’s Of fice of New Urban Mechanics http://newurbanmechanics.org/project/vehicle - side guards/ 361 Patten, J. D., & Tabra, C. V. 2010. Side Guards for Trucks and Trailers Phase 1: Background Investigation www.safetrucks.ca/resources/National_Research_Council_Truck_Side_Guard_Study_2010 - 03 - 01.pdf 362 Riley, B. S., Penoyre, S., & Bates, H. J. 1985. Protecting Car Occupants, Pedestrians, and Cyclists in Accidents Involving Heavy Goods Vehicles by Using Front Underrun Bumpers and Sideguards http://trid.trb.org/view.aspx?id=23795577 2.9 Lightweight Materials Use of lighter materials substitution for steel in body and chassis compo nents also reduces vehicle fuel consumption, although material strength and the role of vehicle mass and design for crash safety must be considered . According to the DOE Materials Technology Program, reducing the vehicle weight by 10 percent can improve th e fuel economy by 6 to 8 percent. 363 With 75 percent of vehicle fuel consumption directly related to factors associated with vehicle weight, the potential benefits of weight reduction enable downsizing the engine and energy storage systems, with correspond ing cost and/or performance benefits. 364 Alternatively, lightweighting can maximize the vehicle payload to increase fuel - efficiency (see Sec. 2.9.4) . NHTSA - sponsored Volpe Center studies of the crash safety performance of future plastics and composite inten sive vehicles (PCIV) evaluated the potential safety benefits and remaining research needs of plastics and composites applications in emerging lighter weight, more fuel efficient, and environmentally friendly vehicles. 365 Aluminum is a mature material that c an provide 40 percent weight reduction compared to steel. Advanced high - strength steel (AHSS) can provide weight savings of up to 25 percent over conventional steel . First generation AHSS is already finding applications throughout the heavy duty vehicle in dustries . One downside is that AHSS still has some of the corrosion issues of conventional steel. 366 A variety of even more lightweight and corrosion - resistant composite materials is in MD/HDV production . Fiberglass has a useful lifetime of 20 - plus years . P lastic composites also provide significant weight reduction, while carbon fiber achieves the highest weight savings: 40 - to 50 - percent lighter than fiber - composite . Carbon fiber reinforced composite (CFRP) is extremely strong, durable, and has no corrosion concerns, but comes at a high cost of production and long processing time, which could slow adoption rate. 367 Typically, a core material such as foam core is encased in a fiberglass shell and other reinforced CFRP configurations to ensure structural strengt h in a crash .

363 C alStart. 2012b. Leading Fleets Take Delivery of World’s First Commercially Available Hybrid Hydraulic Parcel Delivery Trucks

– “Hybrids Without Batteries” www.calstart.org/news_and_publications/CALSTART - in - the news/CALSTART - Press - Releases/worlds - first - hybrid - hydraulic - delivery - trucks.aspx DOE VTP materials Technologies: Goals, Strategies and Top Accom plishments at www1.eere.energy.gov/vehiclesandfuels/pdfs/materials_tech_goals.pdf 364 Oak Ridge National Labora tory. 2012. Oak Ridge National Lab Lightweight Materials Program web.ornl.gov/sci/lightmat/Lightweight.html 365 “Characterizing And Enhancing The Safety Of Future Plastic And Composite Intens ive Vehicles (PCIVs),” 2009, A. Brecher, J. Brewer, S. Summers, and S. Patel at www - nrd.nhtsa.dot.gov/pdf/esv/esv21/09 - 0316.pdf 366 DOE. 2012. Energy Department Investments to De velop Lighter, Stronger Materials for Greater Vehicle Fuel Economy www.doe.gov/articles/energy - department - investments - develop - l ighter - stronger - materials - greater - vehicle fuel , Lyden, S. 2012. It's a Lightweight Material World www.worktruc konline.com/channel/vehicle research/article/story/2012/01/it - s - a - lightweight - material - world.aspx?prestitial=1 367 Lyden, S. 2012. It 's a Lightweight Material World www.worktruckonline.com/channel/vehicle research/article/story/2012/01/it - s - a - l ightweight - material - world.aspx?prestitial=178 2.9.1 Penetration/Adoption Consumer preferences have limited the downsizing options available to vehicle manufacturers, and safety and performance standards have resulted in a very limited ability to reduce weight further with conventional materia ls. 368 However, there are a growing number of lightweighting cases in MD/HDV fleets, especially in transit buses. In 2003, North American Bus Industries began manufacturing a 45 - foot transit bus with a light weight all - composite body, called the Compo Bus. Approximately 400 were manufactured between 2004 and 2008, and the largest fleet is in Los Angeles. Some of them have now been in service for more than 10 years and continue to operate. Mobile Energy Solutions LLC introduced a lightweighted transit bus in 2007 with an all - composite body featuring a fuel cell/hybrid electric propulsion system. 369 In 2009, Proterra debuted a lightweighted fast - charge battery electric composite bus , using a light yet durable fiberglass - balsa wood composite . The EcoRide BE35 bus es, now operating in several U.S. cities, have a re duced composite body weight of 20 - 40 percent over a conventional steel or aluminum bus, is climate resistant, and could provide up to a 600 percent improvement in fuel economy based on FTA testing at Altoo na due to their combination of lightweighting, regenerative braking, and electric power source. 370 UPS tested prototype diesel - fueled delivery trucks with lightweight bodied constructed of a plastic resin material instead of steel . The lightweighted trucks achieved a 40 percent increase in fuel efficiency largely due to the truck’s 10 percent weight reduction, the advanced powertrain technology, and a more aerodynamic design . The body uses high - impact plastic for the lower cladding and one - piece plastic mol ded roof . With a payload capacity that is only 10 percent (700 lb.) less than the company’s standard delivery truck, the 150 - horsepower trucks ran on an Isuzu four - cylinder diesel engine . The lightweighted trucks were successfully field tested in extreme w eather conditions over the course of one year, after which UPS ordered 150 of these trucks to run on high - mileage routes. 371 To date, carbon fiber has been an enabling technology for the composite body of the Proterra bus, and the fuel cells in advanced Van Hool fuel cell buses , 372 but could also become a broadly adopted material in the future if its fabrication costs and volume issues were resolved.

368 Oak Ridge National Laboratory. 2012. Oak Ridge National Lab Lightweight Materials Program web.ornl.gov/sci/lightmat/Lightweight.html 369 Composites World. 2007. New hybrid electric bus takes advantage of composites www.compositesworld.com/articles/new - hybrid - electric - bus - takes - advantage - of - composites 370 Proterra Inc. 2009. Proterra Brings Future of Green Commercial Transit to California Cities With Zero Emission Clean Bus Tour www.prweb.co m/releases/2009/02/prweb1968224.htm ; see also www.proterra.com/index.php/products/productDetail/C29/ and www.proterra.com/product - tech/durability reliability/composite - body/ 371 Kaye, L. 2012. UPS Rolls Out Lightweight Composite Trucks In a Move Towards Energy Efficiency www.triplepundit.com/2012/06/ups - composite - trucks - energy - efficiency/ 372 See Regional Buses Boos CFRP in Alternative Energy at www. compositesworld.com/articles/regional - buses boost - cfrp - in - alternative - energy ; and Proterra at www.proterra.com/index.php/products/productDetail/C32/79 2.9.2 Benefits The Department of Energy launched new initiatives in 2012 for further reducing vehicle weight to impro ve fuel efficiency. 373 Lightweighting can also mean a reduction in maintenance costs because a lighter vehicle body requires less brake power to stop and may cause less wear on tires and brakes. 374 Reduction in MD/HDV mass will reduce crash forces to other v ehicles, although this effect is likely to be small for light - duty vehicles since truck lightweighting will have only a small effect on the mass differential . This benefit may be canceled out further by the fact that light - duty vehicles are also undergoing lightweighting . Replacing cast iron and traditional steel components with lightweight materials

 including advanced high - strength steel, magnesium, aluminum, and carbon fiber composites

 can allow vehicle manufacturers to include additional safety device s, integrated electronic systems, and emissions control equipment on vehicles without increasing their weight . In this way, advanced lightweight materials promise to enhance vehicle safety and performance of vehicles, while boosting fuel economy. 375 As with most FE technologies, individual payback and economic benefits will depend on the vehicle class and drive cycle . Vehicles that travel long distances and those with high kinetic intensity (e.g., transit buses) stand to benefit the most from lightweighting. 376 2.9.3 Safety Considerations In all cases, the safety and crashworthiness of lighter weight vehicles is a significant consideration, as well as other environmental health and safety issues associated with new materials and process technology. 377 The predominant g rade aluminum for body manufacturing loses 80 - percent of its strength when welded, so it may not be a suitable material for work trucks with a long service cycle . For fiberglass composite materials, it is important to correctly mount accessories . Concentra ted loads at the point of attachment may result in damage of a fiberglass panel . The downside of some plastic composites may include their susceptibility to heat, degradation, and brittleness and over

373 See www.doe.gov/articles/energy - department - investments - develop - lighter - stronger - materials - greater - vehicle fuel and http://energy.gov/articles/obama - administration - announces - 142 - million - new - funding - develop - lightweight materials 374 Lyden, S. 2012. It's a Lightweight Material World www.worktruckonline.com/channel/vehicle research/article/story/2012/01/it - s - a - lightweight - material - world.aspx?prestitial=1 375 DOE. 2012. Energy Department Investments to Develop Lighter, Stronger Materials for Greater Vehicle Fuel Economy www.doe.gov/articles/energy - department - investments - develop - lighter - stronger - materials - greater - vehicle fuel 376 Lyden, S. 2012. It's a Lightweight Material World www.worktruc konline.com/channel/vehicle research/article/story/2012/01/it - s - a - lightweight - material - world.aspx?prestitial=1 377 Quintiere, J. G. , Walters, R. N., & Crowley, S. 2007. Flammability Properties of Aircraft Carbon - Fiber Structural Composite www.fire.tc.faa.gov/pdf/07 - 57.pdf80 time when exposed to UV radiation from sunlight. 378 Howev er, thermoplastics resistant to UV and weathering have been developed, 379 and no examples of such lightweight material failures on MD/HDVs were identified in the literature . The use of composites, aluminum, and fiberglass may result in less protection to tru ck drivers in crashes because of lower crush strength, but no studies or work with significant results were identified. The FAA has sponsored and evaluated fire - safe polymers and polymer composites 380 and examined the flammability properties of carbon fiber composites for structural applications . 381 2.9.4 Findings and Conclusions No safety incidents involving or attributable to lightweighting of MD/HDVs were identified in the literature. The fuel economy benefits of reducing vehicle weight have been clearly demonst rated over the past few years in operational fleet pilots and all - composite buses in transit fleets . Lightweighting vehicles may make it possible to install additional safety or environmental equipment on MD/HDVs to further improve their performance . Moreo ver, rightsizing vehicle payloads, i.e., increasing payload per vehicle as a result of lightweight body materials, could enable reductions in the total truck fleet size, reduced VMT, and a proportional reduction in crashes. 382 NHTSA sponsored research on the crash safety of Plastic and Composite Intensive Vehicles (PCIVs) identified progress in and research needs for characterizing and enhancing the safety of automotive lightweighting composites in structural applications . 383

378 Lyden, S. 2012. It's a Lightweight Material World www.worktruckonline.com/channel/vehicle research/article/story/2012/01/it - s - a - lightweight - material - world.aspx?prestitial=1 379 See www.dotmar.com.au/uv - resistance.html 380 See “Fire safe po lymers and polymer composites,” 2004, FAA report at www.fire.tc.faa.gov/pdf/04 - 11.pdf 381 See ”Flammability properties of aircraft carbon fiber structural composites,” 2007 at www.fire.tc.faa.gov/pdf/ 07 - 57.pdf 382 Lyden, S. 2012. It's a Lightweight Material World www.worktruckonline.com/channel/vehicle research/article/story/2012/01/it - s - a - lightweight - material - world.aspx?prestitial=1 383 A. Brecher et al, “Characterizing and enhancing the saf ety of future PCIVs,” ESV - 21 paper 09 - 0316, at www nrd.nhtsa.dot.gov/pdf/esv/esv21/Track%2025%20Oral.pdf81 3 SUMMARY OF SUBJECT M ATTER EXPER T INPUTS ON MD/HD SA FETY IMPACTS OF FE TECHNO LOGIES 3.1 Introduction: Respondents and Fleet Profiles To obtain primary experience information on safety benefits or disbenefits, interviews 384 were conducted with managers of several large “green” and diverse corpo rate truck fleets and with managers of public transit fleets with significant fuel efficiency technology adoption . These fleets were selected based on published reports on green technology fleet adoption 385 and are the same large “green” fleets that were an alyzed for safety performance relative to conventional fleets in our queries of CSA and FARS databases . In addition, technical experts from medium/h eavy - d uty vehicle FE - related OEMs, suppliers, and integrators, as well as FE experts from Gov ernment agencie s were interviewed . The results represent the viewpoints of each interviewee and do not represent the views of their organization or the U.S. Department of Transportation. Table 3 - 1 lists the organizations of the subject matter e xperts who were interviewed . Table 3 - 1 : Broad Cross - Section of Subject Matter Experts Interviewed Corporate fleets Public transit Industry Government Coca Cola Enterprises Houston METRO EATON Corporation Arg onne & National Renewable Energy Laboratories Frito Lay Long Beach Transit Vanner, Inc. FMCSA Verizon Communications Santa Barbara Metropolitan Transit District (SBMTD) Parker Hannifin Corporation EPA SmartWay ARAMARK Washington DC Metropolitan Area Transit Authority (WMATA), or Metrobus system BAE Systems CALSTART

DHL/Exel Daimler Trucks North America (DTNA) DOE Clean Cities Program The private and public green fleet managers who were interviewed spanned a wide range of MD/HD vehicle types, F E technologies, geographic locations, types of services, and typical drive cycles . These major fleets are among those that have joined the DOE National Clean Fleets Partnership. 386

384 The oral communications with fleet managers were non - standardized, and varied on subject matter depending on the fleet type (such as public transit or government). 385 See www1.eere.energy.gov/cleancities/national_partnership.html for flee t list See www1.eere.energy.gov/cleancities/national_partnership.html for fleet list 386 Ibid.82 The Coca Cola Enterprises fleet includes 15,000 MD/HDVs total; 10,000 are C lass 7 or 8 . Most of the fleet operates short distance trips, with fewer than 500 tractors driving long distances . Since 2007, the fleet has included 760 hybrid - electric trucks (representing a small vehicle fraction of about 5 %) , 2 LNG and 5 CNG trucks acq uired 1.5 years ago, 8 fully electric Smith Newtons acquired two years ago (GVW 19,000 lbs.), and six Navistar E - star electric trucks (GVW 14,000 lbs.) acquired one year ago . Coca Cola Enterprises has also adopted idle reduction in all of its vehicles, spe ed governors, and telematics packages, along with a driver training program to ensure eco - driving and fuel savings. Frito Lay has about 22,000 fleet vehicles, excluding trailers . The fleet includes 1,200 Class 8 over - the - road tractors, 4,000 trailers, and a delivery fleet of 4,000 straight box trucks. The fleet has reduced its fuel consumption by 14 percent in the past four years despite a concurrent 3 percent growth in goods volume . Frito Lay has set a corporate sustainability goal of 50 percent fuel burn reduction by 2020 . It will deploy 275 electric trucks by the end of 2012 and become the largest domestic commercial fleet of all - electric trucks . The entire fleet has broadly implemented idle reduction since the late 1990s, aerodynamic technologies program for its trailers since 2007 - 08, as well as speed limiters and required driver training . About 70 CNG tractors are also being deployed in 2012. The Verizon Communications fleet, consisting of the Telecom, Wireless, and Enterprise divisions, has 6,000 MD/HD Vs . The fleet - wide fuel efficiency average is 11 mpg (c.f. typical HD truck fleet average of 5.7 mpg) . A large fraction of the MD/HDV diesels are equipped with 5 - minute idle reduction . Though there are no alternative - fueled MD/HDVs, the fleet includes 15 h ybrid and 10 CNG light aerials (up to 30 ft. reach booms). The earliest hybrids are from 2008 - 09, with most hybrids and the CNGs online since 2010 . Aramark ’s Food and Facilities division fleet is piloting five MD hybrid gasoline - electric Azure Dynamics co nversions of 14,000 lbs. GVW E - 450s . Eight propane - powered vehicles are in service, though not currently fueled on site, and the fleet plans to deploy new Smith electric trucks soon . A multi - stop urban duty cycle is typical of Aramark vehicle fleet operati on . Several different telematics pilot program are underway. DHL Supply Chain Unit’s fleet provides point - to - point delivery of heavy loads, with 1,100 Class 7 - 8 tractors in the United States , but no alternative fuels are currently in use . “Teardrop” aero dynamic trailers have been use in the U.K. fleet, but not in the United States The fleet duty cycle includes a mix of highway and urban driving . Speed limiters have been universally adopted for several years . DHL has also been conducting a telematics and d river coaching studies on 150 box trucks (under 26,000 lbs.) . Houston Metro (Metropolitan Transit Authority of Harris County) has o perated 350 hybrid electric buses, with 122 parallel hybrid - electric buses first deployed in 2007 . Commuter buses travel mos tly on the expressway, with little or no urban driving, while other city routes have more stops. More recently, 130 series hybrid - electric buses have been deployed, although the majority of the fleet remains diesel . The Houston transit bus fleet has gained experience with both lithium ion and nickel metal hydride batteries .83 Long Beach Transit (LBT) operates 87 gasoline electric series hybrid buses out of a fleet of 247 buses, with hybrids in service since 2007 . LBT maintenance and operations staff has had 5 years and more than 11 million hours of service with the hybrid electric buses, which use either ultracapacitors or batteries . 64 Gillig Corp. CNG buses were also rolled out in 2012, fitted with CNG tanks in rooftop compartments . The Santa Barbara Munic ipal Transit District (SBMTD) has operated and maintained for 20 years a fleet of electric 22 - foot shuttle buses from Ebus, with a daily range of 60 - 75 mi between charges . Ten other electric buses from different manufacturers were tested, but withdrawn fro m service . Currently, the fleet of 108 buses consists of the 20 electrics; 18 diesel electric parallel hybrids (Gillig, with Allison drivetrains); and the rest diesel . SBMTD has experience with all battery types for energy storage: lead acid, lithium ion, and nickel cadmium batteries . To save on battery energy and extend range, the SBMTD electric buses have no hotel loads or auxiliary power drains and all HVAC needs are met by opening or closing the bus windows. The Washington Metropolitan Area Transit Aut hority (WMATA) has operated New Flyer hybrid electric buses with Allison parallel drivetrains since 2006, including standard 40 foot and longer articulated models. The number of hybrid electric buses is approximately 400 out of a total bus fleet of 1,500 . WMATA has also been operating over 300 CNG buses since 2002. Although not interviewed, the Los Angeles Metro has safely operated CNG buses for over two decades : it completely converted its transit bus fleet to CNG in 201 1 , and currently operating over 2, 200 CNG buses . 387 Similarly, the New York City Metro Transit Authority (NYMTA) has safely operated a large fleet of New Flyer CNG buses, ordering in 2010 475 new buses in addition to 190 older CNG buses . 388 3.2 Fuel Efficiency Technology Clusters and Safety Concer ns Reported A theme that emerged from interviews with the SMEs is that fuel efficiency technologies were often introduced into fleets as synergistic “clusters.” For example, intelligent transportation systems (ITS), GPS vehicle tracking, and route optimiz ation were frequently implemented together . Automatic stop - start and other idle reduction technologies were typically bundled with driver training . Hybridized or electric drivetrains typically incorporate regenerative brake technology . As pointed out by a number of SMEs, combining complementary technologies and driver training is important to obtain maximum FE, environmental, and economic benefits . 3.2.1 Alternative Clean Fuels One corporate fleet manager reported that the only problem with their CNG tractors wa s a cylinder liner issue that was not specific to the CNG propulsion. It was not a significant safety hazard .

387 See “Diesel era ends for MTA buses” 2011 at http://articles.latimes.com/2011/jan/13/local/la - me - buses 20110112 388 See http://energy - vision.org/new - york - citys - mta - upg rades - its - cng - bus - fleet/84 Another corporate fleet with CNG trucks in service since 2010 reported no safety incidents related directly to FE technologies. This fleet has ex perienced the same accident rates across its FE and conventional vehicles . Even though employees usually blamed any accidents on the truck equipment, they did not blame deployed FE technologies, such as hybrid, CNG, and idle reduction . While he did not rep ort any first - hand safety incidents, the fleet manager was very skeptical of CNG vehicles due to concerns about the safety of high pressure (4000 psi) CNG cylinders potentially exploding in a crash scenario or if ruptured . He also pointed out that shared g aseous/liquid fueling garages are spark - protected at ground level, but not necessarily at ceiling level where natural gas would rise and create the potential for ignition . Particularly in diesel garages that only serve a few CNG vehicles, and especially i n cold climates, he stated that best practices and engineering controls for safe ventilation are important . He related anecdotal reports that more people were hurt by opening high pressure CNG lines than by electric shock, e.g., from batteries and high vol tage wiring in electric hybrids. The fleet manager of a third corporate fleet believed that propane is as safe as or safer than gasoline, based on personal experience filling propane vehicles . This manager reported no safety issues with the company’s propa ne or hybrid gasoline - electric trucks . Though he did not perceive any safety issues with alternative clean fuels, he recommended “better public education about fuels like CNG” so that potential adopters “would not be scared.” Engineers at a major truck OEM alluded to the general safety risk arising from multiple small suppliers that implement components downstream without performing extensive tests, owing to the low volumes of retrofitting or producing alternative fuel vehicles . They related an incident in which a supplier began fitting natural gas engines onto one of this company’s truck models, but incompatibilities led to overheating and brake fade. This was only discovered after several vehicles had been sold . The engineers said that the risk associated with the high number of configurations and low volumes of alternative fuel vehicle production also applies to the OEMs . HD vehicles are a mix of components from many different suppliers, and unlike commoditized light - duty vehicles there are not generally t he engineering resources to system - test, integrate, and model all potential configurations . The engineers noted that there have not been any significant safety problems to date, other than the NG engine retrofit problem. A U.S. Gov ernment official stated t hat as the first generation of CNG tanks nears the end of their 15 - year service life, there is concern within the MD/HDV OEM and engine industry that some expired tanks will not be properly disposed . He reported the case of a salvage yard operator who mish andled the CNG tanks on a vehicle and caused them to rocket into a nearby building . He added that conventional automotive technicians may have the skills or knowledge to deal with natural gas fuel systems . Often NGVs have been unsafely returned to service after a collision without proper inspection for fuel system damage . These defective or weakened NG tanks have resulted in fatal or injurious explosions when they were filled . The official also stated that enforcement of the Federal Motor Vehicle Safety Sta ndard (FMVSS) 304 389 end - of - service replacement provisions for CNG tanks would be critical to make sure that expired tanks are not

389 NHTSA. 2009. FMVSS 304 CNG fuel container integrity www.nhtsa.gov/DOT/NHTSA/NVS/Crashworthiness/Alternative%20Energy%20Vehicle%20Systems%20Safety%2 0Research/811150.pdf85 unscrupulously re - sold, which could result in similar safety incidents. 390 Concerning the indoor servicing of CNG vehicles, he w as aware of one case in which an NGV was operated in a shop in the presence of an active flame heater that led to an explosion. 3.2.2 Drivetrain Hybridization and Electrification Safety One corporate fleet manager reported that heavy - duty hybrid electric tractor s achieved an actual 13 - 22 percent fuel efficiency FE gain compared to ICE tractors . The fleet manager at this company was very satisfied with their alternative fuel medium - and heavy - duty vehicles’ operation and maintenance safety . The manager’s main conc ern was about the too - short (5 - year) battery life on the hybrids, as in his experience batteries are dying faster than expected and are expensive to replace . This fleet manager found that some drivers refused to drive the non - air conditioned E - Star electri c trucks in the summer . However, there were no safety issues for EVs related to hot weather . Indeed, both the E - Stars and the Smith electric trucks were reported as “fairly reliable” in high summer heat . Technician safety training was identified as a need for the potential high voltage hazards involved in servicing hybrid and electric vehicles, but he stressed that there have been neither electrocution incidents nor close calls. Although electric motors have more torque at low speeds than ICEs, a corporate fleet operating Smith Newton electric trucks (E - trucks) found that they do not accelerate faster than ICE trucks, due to programming that prevents breaking of traction . The reliability and availability of the Smiths was also measured as about 300 days mean time between failures (MTBF), which is 50 percent better than the MTBF of ICE trucks . The only potential concern for E - trucks is their limited all - electric range of 50 - 65 miles, which could become a safety issue if it were stranded in traffic . In addition, while the maximum vehicle speed is 55 mph; going uphill could be limited to lower speeds . Therefore, each E - truck route must be “certified” for safe operation to prevent stranding . With this best practice and driver training, the company has never experie nced a stranded E - truck, except for one case in very cold weather. In one private fleet, no safety issues were reported with regard to gasoline - electric hybrid truck conversions . The manager said that they have experienced 35 percent FE savings and that the hybrid conversions have been “beneficial overall.” A major manufacturer of parallel hybrid drivetrains pointed to the extensive incident - free history of its hybrid electric MD/HDVs (6,000 vehicles over 300 million miles) as evidence of HEV safety for the past five years . The company engineers stated that the rechargeable energy storage system undergoes multiple safety tests and is designed with fail - safes for various misuse and abuse scenarios . Rogue acceleration is prevented through error checking in the hybrid control unit, and less wear and tear on brakes in the hybrid vehicles may lead to improved brake safety by reducing brake fade . 390 American Trucking Association. 2009. Expanding ATA’s Safety Agenda Executive Summary www.truckline.com/Newsroom/Policy%20Papers/Safety%20Task%20Force%20Report.pdf ; Natural Gas Vehicle Owner Community. 2011. CNG tanks never expire? http://c ngchat.com/forum/archive/index.php/t - 7264.html Review of Limited Calendar Service Life for ANSI NGV2/FMVSS 304 CNG Fuel Containers, Aug . 14, 2012 at www.cleanvehicle.org /technology/CVEFLimitedLifeRationaleR3.pdf86 The weights of parallel hybrid vehicles are similar to those of conventional counterparts, so their handling is sim ilar, according to these engineers . What may be a safety risk is the highly variable integration of hybrid components downstream by bodybuilders: the case was recalled of an operator being stranded in a bucket without power . Better standardization, knowled ge sharing, or new best practices may be needed in the future to ensure operational safety . Another potential safety concern is the uncertain battery lifetime due to variability of climate and duty - cycles. Without state - of - charge indicators, this could con ceivably leave vehicles underpowered or stranded if the battery degrades, and is not serviced or replaced in a timely manner . The engineers noted that HEVs and EVs share the same potential battery - related safety issues and required safeguards and best - prac tices in prevention and maintenance. Another hybrid - electric drivetrain company expert concurred that its 3,800 series hybrid electric buses (HEB) in operation around the world had a long and mostly incident - free history . This chief engineer pointed out t hat minimal vehicle chassis changes are needed, and that the vehicle handling is deliberately similar to a conventional bus . Multiple fail - safes are designed against electrocution, and the engineer stated that the bus’s quieter operation is not a detectabi lity hazard to other road users . The engineer stated that the breakdown rate of hybrid electric buses is not any higher than that of ICE buses . Moreover, a hybrid bus is still able to pull off the road when there is a failure with the ICE or its electric m otor, and this feature has been used in service . At the same time, though, a battery cooling system failure had to be addressed through engineering redesign, suggesting the need to evaluate best practices for preventing damage to new FE subsystems that may not be compatible with existing protocols

— in this case, pressure washing of the vehicle that short circuited the ESS. The operations manager of a transit agency that has used hybrid diesel - electric buses with two different drivetrains since 2007 reported occasional early safety issues with over - speeding of the traction motor; when this occurred, the bus entered a creep mode and had to be taken out of service . There was an instance of an operator who tried to keep the traction motor working in creep mode, s horted out the plate, and caused hydraulic fluid to leak down the bus. This failure mode only happened once on one of the hybrid drivetrain types operated by the transit agency . A recommended countermeasure was better operator training to deal with emergen cies on hybrid buses and to understand their failure modes. Another transit agency operations manager reported that their HEBs did not fully deliver the promised FE gains, but that they had brought a 90 percent decrease in brake maintenance costs versus d iesel buses . The ultracapacitors used as the energy storage system on some of the buses developed an acetonitrile electrolyte leak that had to be fixed under warranty . The mean time between road calls for hybrid buses at this agency was comparable to diese l: 9,000 versus 11,000 hours . The electric buses (EBs) operated by an urban transit agency have had no safety issues, but they have had service interruptions, according to the fleet manager, which mainly involved older lead acid batteries . Newer lithium i on batteries used by the fleet have been far more reliable . When the hybrid electric buses occasionally break down while in service, they have to be towed to the central depot. However, experience with HEB/EBs shows that their brakes last longer than the b rakes of diesel buses . The fleet manager said that the agency’s experience with electric and hybrid buses has been positive overall and that they are very popular with users.87 Regarding hybrid hydraulic vehicles (HHVs), an engineer with a major drivetrain manufacturer stated that the basic technology used in these drivetrains is proven technology, with many decades of engineering knowledge . He stated that the company’s HHV drivetrains are designed for the 10 - year lifetime of a heavy - duty truck . Also, there are no safety issues associated with the mass transfer of hydraulic fluid between accumulators, and multiple redundancies exist against rogue vehicle movement commands . His chief recommendation was for continued improvement of vehicle part integration to p revent any possibility of conflicting system signals . Hydraulic hybrid drivetrains have similar failure modes to existing hydraulic systems on MD/HDVs , i.e., leaks . Due to the high fluid pressure (5,800 psi), a leak can lead to high - velocity fluid eject ion that could cause potential injury to bystanders . There is always a risk of vehicle stranding due to leaks and loss of propulsion. Several of these types of strandings were reported by another HHV drivetrain manufacturer . At the same time, the anti - lock brake system (ABS) friction brakes on HHVs provide a backup in case the hydraulic system fails, ensuring safe stopping capability . The fact that the friction brakes are cool may also improve their stopping performance, a safety benefit . The engineer state d that acceleration of the HHV is not unsafely quiet, and that drivers report they like operating the HHVs . Although the engineer did not have data, he suggested that it is possible that the extra 1,700 pounds of weight added by a series HHV drivetrain may affect the braking distance and handling of the truck . Maintenance best practices implementation in an HHV fleet is considered safety - critical to and includes regular inspection of hydraulic hoses, oil, and accumulators to detect and address leaks. 3.2.3 Intell igent Transportation Systems and Telematics The manager of one corporate fleet reported that since installing both auto start - stop and telematics for monitoring of vehicle operation on all their vehicles two years ago, the fraction of unproductive engine operating time has decreased from 30 percent to 9 percent . He added that no safety incidents were documented in the fleet for this cluster of FE technologies. Another company that had outfitted 80 percent of its fleet with GPS and telematics that monitor F E reported that out - of - route miles, acceleration, and congregation events (when drivers use their trucks to meet and socialize during work hours), decreased 10 percent under engineered route lengths, compared to 20 - 30 percent over engineered route lengths prior to having training and installing telematics . Hence, the use of telematics on vehicles has led to a reduction in vehicles miles traveled VMT, which likely led to fewer crashes . The fleet manager of this company also believed that efficient drivers ar e safer drivers, though the company did not yet have data to quantify this. 3.2.4 Speed Limiters Two corporate fleet managers both stated that 65 - mph speed limiters have been universally in place on all their respective vehicles since the late 1990s, with no res ulting safety issues reported . One fleet manager believed that speed - limiter - related safety concerns could only be encountered when trucks pass other vehicles on the highway instead of staying in the right - hand lane behind other vehicles as suggested . He r ecommended combining speed limiters and driver training programs to improve truck safety.88 3.2.5 Idle Reduction (Auto Stop
- Start) 391 Idle reducing auto start - stop was implemented on nearly the entire fleet of a major company about 15 years ago . Although the resulti ng FE gain is difficult to measure, there have been no safety - related concerns . Although FE gain data is operationally difficult to measure at one company with broad idle reduction adoption, there have been no safety issues with the engine shut - off featur e . No employees have blamed any mishaps on the idle reduction feature. A truck auxiliary power supplier and integrator stated that idle reduction technology and electric auxiliary power systems in aerial work trucks have shown no known safety issues . Acco rding to the engineer, the proof that the system is working seamlessly is that drivers don’t realize the system is ever turning the engine on and off to recharge the vehicle batteries . He cited a test of the system on 22 aerial trucks in Montreal that demo nstrated 16 - 30 percent FE gains . The utility company testing the system enforced idle reduction by cutting off power to work systems whenever the engine was on, so drivers were unable to cheat. One U.S. Gov ernment idle reduction program leader/coordinato r stated that in 10 years she has seen no safety incidents or issues due to idle reduction equipment . If there had been any serious safety concern, this researcher believed it would have shown up . In an extreme temperature scenario when a vehicle engine au to - stops and then has to restart, the auto - start would usually be run by an APU not linked to the rest of the motor system; the researcher did not believe that auto stop - start could cause a breakdown on the highway or at a stoplight, which are the failure scenarios that could potentially cause a crash or congestion. 3.2.6 Driver Training: Human Factors and Operation Issues One of the corporate green fleets partnered with two outside companies to implement a comprehensive driver - education program focused on FE tec hniques: anticipation, coasting , eliminating unnecessary idling, keeping momentum, and keeping distance . Eco - driving “rodeos” are also held to train drivers. Another corporate fleet manager stated that he is confident that “fuel efficient driving is safe d riving” and vice versa . His company has committed to train all of its drivers and reports that all trained over - the - road drivers have achieved a 6 - 20 percent FE improvement. As a general observation, the fleet manager stated that when deciding on fuel effi ciency technology implementation, “Fleets don’t necessarily consider the safety impact unless there is a negative risk when picking a fuel efficiency technology, or unless there is good data on the positive safety impact of the FE solutions.” LCVs were s upported by one of the corporate fleets as a fuel efficient way to transport low weight cargo . The corporate fleet SME interviewed stated that he “could not think of a single road safety incident involving LCVs in the western United States.” This anecdota l view was
391 The North American Council for Freight Efficiency (NACFE) 2012 study on idle reduction early adoption costs and benefits at http://nacfe.org/wp - content/uploads/2012/07/NACFE - 2012 - Anti - Idling - Study - 062812.pdf89 supported by engineers at a truck OEM, although they added that the longer stopping distance of heavier LCVs is a potential safety disbenefit. One large corporate green fleet has deployed a telematics driver - monitoring system called SmartDrive 392 on 150 box trucks and combined this technology (which has internal cameras to monitor texting, distractions, and about 70 other “driving defects”) with daily driver coaching . Monitoring and recording of driver behavior, combined with coaching, has reduced distracted and aggressive driving and provided significant FE and safety benefits . Since implementation, the mean distance between driver defects such as texting and hard braking has doubled to 600 miles from 300 miles . This fleet manager believes that te chnological solutions and driver coaching should occur in tandem for maximum FE and safety benefit, and he believes that driver training is the more critical element of the two . He agreed that there is evidence of telematics alone decreasing unsafe behavio r . His company in the UK - implemented GreenRoad 393 for on board behavioral feedback found it reduced “driver defects” by 75 percent on 15 test vehicles. 3.2.7 Tire Systems: Wide Base, 394 LRR, 395 and TPMS 396 Safety Issues Wide base tires were considered for use by one co rporate green fleet manager, who recognized some benefits, but was concerned that if a tire blowout occurs there is no redundancy . This lack of redundancy was considered a potential safety hazard of wide base tires . However, a mechanic at the same company stated that he had never experienced any problems with the wide base tires installed on the two tractors and 14 trailers within the fleet . Other concerns articulated were not safety - related, e.g., the tires are “very expensive” and so far have poor availab ility . Another corporate fleet manager reported that he installed a TPMS without real payoff, because the TPMS flaw detection was not early enough to prevent tire damage. This fleet manager believed that TPMS is unlikely to prevent blowouts, when compared to monthly yard checks of tires . At the same time, his parent company has been running wide base tires for some years now, but it is not yet clear if these tires have produced notable FE gains. Engineers at one truck OEM stated that they were unsure why super - single tires are not catching on despite the technology’s proven FE benefit . They believed that the slow adoption of single tires

— and of other FE technologies, for that matter

 is probably not due to degraded safety performance, but rather due to fear s of increased downtime, specifically for tires . The perception is that the downtime for single tires is twice as high as for duals . This would therefore be a reliability issue and not a safety issue.

392 SmartDrive Systems. 212. SmartDrive www.smartdrive.net/ 393 California Natural Gas Vehicle Coalition. 2012. Cummins Plans 15 - Liter HD Engine www.cngvc.org/pdf/newsletter s/CalNGVNews_041612.pdf 394 See EPA SmartWay Verified Technologies for fuel efficiency improving tires at www.epa.gov/smartway/forpartners/technology.htm 395 EPA. 2012. Low Rolling Resistance Tires A Glance at Clean Freight Strategies www.epa.gov/smartway/documents/partnership/trucks/partnership/techsheets - truck/EPA - 420 - F10 - 041.pdf 396 North American Council for Freight Efficiency. 2012c. 2012 Tire Pressure Study http://nacfe.org/wp content/uploads/2 012/07/NACFE - 2012 - Tire - Pressure - Study - 062812.pdf90 Without citing specific experience, these engineers su ggested that LRR tires could negatively affect truck stopping distance and stability control, a potential safety disbenefit . They stated that LRR tires can make passing NHTSA stability control tests more difficult for vehicles, and they were hesitant to re commend them . 3.2.8 Aerodynamic Components and Safety An aerodynamic retrofit program for trailers of a green corporate fleet started in 2007 . Although the associated FE gain has been difficult to measure, the safety performance of aero components was tested ex tensively in wet and other driving conditions, including pressure envelope interactions with other vehicles, and crosswinds. Aerodynamic system safety was deemed solid, with no instances of detaching . A major truck manufacturer has deployed fuel tank fair ings, side extenders around sleepers, and over - the - sleeper fairings as part of its high - efficiency line of products for over - the - road trucks . While the engineers had heard concerns about railroad crossings and dock approaches damaging under - trailer skirts, they had never actually observed such problems . They also had no knowledge of any aerodynamic components that have detached from vehicles . This same manufacturer is currently studying the use of cameras to replace rear view mirrors on over - the - road truck s, which would offer approximately 1 percent FE improvement . The engineers stated that rear - view cameras have the potential to fail and that there are more ways for cameras and displays to fail than for mirrors . According to these engineers, the failure of a rear view camera is a safety risk comparable to losing a tire, since the vehicle could then no longer legally (or safely) be operated . These engineers said that an important consideration for aerodynamic components is that drivers are required to regul arly inspect their vehicles . Covering underside or other components with aerodynamic fairings can make them harder to inspect; for example, CNG relief valve shrouds, wheel covers, and certain fairings . Drivers and inspectors need to be able to see through wheel covers and to be able to access lug nuts through them. These covers must also be durable to withstand frequent abuse . While this manufacturer did not offer an active fifth wheel, intended to reduce the cab - trailer gap, the engineers stated that its safety could be ensured through a variety of fail - safe mechanisms, such as ratcheting . 3.2.9 Lightweighting Materials As discussed in Section 2.9, there are multiple lightweighting materials options for weight reduction of MD/HDVs to improve their fuel efficie ncy without loss of crashworthiness. These materials include aluminum, fiberglass composites, advanced high - strength steel, plastic, and carbon fiber composites in either structural or internal padding applications. Although light weighted vehicles offer i mproved maneuverability and shorter stopping distance, for specific lightweighting materials, they may also result in decreased survivability in vehicle fires . Engineers at one heavy - duty truck OEM suggested that new lightweight materials (such as carbon f iber composites and resin epoxies) are making it harder to fight vehicle fires . They stated that it may take less time for a vehicle to become fully engulfed in fire with more such materials91 incorporated, although they did not cite any actual experience . T hese engineers recalled a conference speaker who claimed that when “a lightweight vehicle fire begins at highway speed, it could be too late by the time the vehicle stops.” More potential crashworthiness safety issues related to lightweighting vehicles w ith plastics and composites were discussed in a 2007 NHTSA/Volpe report and research roadmap. 397 3.3 Conclusions Regarding Key Safety Issues Based on the collective input from SMEs and the concerns raised, the perceived potential hazards associated with the adop tion of FE technologies by MD/HDVs were summarized. Available countermeasures were also identified, largely based on the SME inputs . The top five FE MD/HDV safety issues by perceived potential hazard were identified as follows, in no order of precedence.
• P otential ignition or explosion scenario in shared natural gas and liquid fuel indoor fueling facilities . Since gaseous fuels rise whereas liquid fuel vapors sink, the fire protection requirements for servicing vehicles indoors that use each type of fuel a re different . Ignition protection in diesel or gasoline facilities is typically at ground level; natural gas facilities must eliminate ignition sources near the ceiling . Due to the high cost of a dedicated NG fueling facility, some fleets may use shared fu eling facilities that service both kinds of vehicles . Robust countermeasures include strictly fueling NGVs in outdoor facilities, if the climate permits, or enforcing strict compliance with NFPA 52 and/or NFPA 57 codes for any facility that serves CNG or L NG vehicles, at any point in time . Engineering controls such as methane detectors, visual/audible alarms, induction - motor HVAC equipment, and other safeguards to prevent ignition in NGV depots are likely to be more effective than relying on process control s, such as manually opening doors or vents whenever an NGV is brought into a shared indoor facility.

• Degraded or expired CNG tanks that remain in service are more likely to rupture . The first generation of CNG tanks is reaching the end of its service lif e . There is no national uniform oversight of their proper decommissioning and destruction . There are reports of expired or damaged CNG tanks being unscrupulously resold through shops and online, e.g., on eBay. 398 FMVSS 304 requires a statement to be placed o n the tank by the manufacturer: “This container should be visually inspected after a motor vehicle accident or fire and at least every 36 months or 36,000 miles, whichever comes first, for damage and deterioration.” Although FMVSS 304 does not require dest ruction of the aging CNG tank after 15 years, it does require a statement: “Do Not Use After (manufacturer must insert the month and year that mark the end of the manufacturer’s recommended service life for the container).” In addition, NGV training would
397 Report No. DOT HS 810 863 “ A Safety Roadmap for Future Plastics and Composites Intensive Vehicles,” Nov. 2007, at http://volpedb.volpe.dot.gov/outside/owa/vntsc_outside.product_repository.display_item?p_doc_id=30707 398 What happens when your CNG tanks expire? At www.government - fleet.com/article/print/story/2010/05/what happens - when - your - cng - tanks - expire.aspx92 minimize any safety risk for automotive mechanics who service NGVs to ensure that damaged CNG tanks are not placed back in service without the necessary inspection and/or replacement at end - of - service life. • Flammability of lightweighting materials and toxicity of burning byproducts . The SMEs stated that fiber reinforced composites, such as the carbon reinforced polymers, used in high end and NASCAR racing cars, are more flammable than steel . The fire safety and health hazards of burning composites inc lude the potential release of volatile organic compounds, toxic microscopic fibers, and combustion products . For instance, carbon fiber composites and resin epoxies used in aircraft structural applications are more flammable and can burn completely, releas ing toxic airborne fibers and other byproducts. 399 The SMEs suggested that although the probability of such an event might be low, the consequence could be of medium to high severity and the fire safety and environmental health performance would benefit fro m further study. Passive fire protection coatings, such as Vermitex, can be integrated to address potential flammability hazard of these materials . Fire safety of light - weighted MD/HDVs could benefit from further study, since both fire performance and burn byproducts toxicity depend on the choice of lightweighting materials and their structural or interior application. • Low - rolling resistance tires may increase stopping distance and degrade stability control . An SME suggested LRR tires could introduce a sig nificant safety concern if they increase stopping distance and degrade stability control . Potential countermeasures to offset a degradation in stopping distance or in stability control include vehicle lightweighting, improving driver training, and reducing vehicle speed limits, e.g., by installing speed limiters . • Incompatible FE components and subsystems . The integration of FE vehicle subsystems has been low production volume, with relatively sparse engineering and validation resources allocated for each vehicle configuration . Although SMEs only cited two concrete examples where this led to safety issues, they suggested that the probability of integrating incompatible components might be medium to high (consistent with the Risk Matrix shown in Figure 5 - 1), and that the consequences warrant further study . Possible countermeasures include standardizing designs and equipment across manufacturers, and utilizing whole vehicle crash tests and safety certification that account for the entire suite of on - board subs ystems . Increased standardization, knowledge sharing, and development of best practices could help to ensure operational safety of FE MD/HDVs. In addition to the above top five perceived potential safety issues, the SME input revealed several other finding s about the impacts of FE technology on safety performance, as well as on

399 See FAA 2007 report “Flammability properties of aircraft carbon fiber structural composite” at www.fire.tc.faa.gov/pdf/07 - 57.pdf ; and Gandhi FAA article “Post - crash health hazard s from burning aircraft composites” at www.aviationfirejournal.com/aviation/library/VOL6 - Hazards.pdf93 non - safety considerations . For example, multiple SMEs concurred that FE technologies offer benefits beyond fuel cost reduction and environmental compatibility . These SMEs reported t hat FE technologies reduced their fleet maintenance costs. This could result from less frequent brake replacements when regenerative braking was incorporated, fewer moving parts in the case of electric drivetrains, or less engine wear in hybrid hydraulics that launch the vehicle from a stop. SMEs accounts indicated that, although electric and hybrid electric vehicles contain onboard electric propulsion and energy storage systems with high voltages, there have been no significant safety incidents . The probab ility of electrocution by electric vehicle energy storage systems is low, as long as personnel and first responders are properly trained . Furthermore, additional layers of engineering safeguards to prevent electric shock are continually being added by the OEMs . In terms of hybrid vehicle operational safety, the requirements for dealing with emergencies such as a disabled hybrid drivetrain MD/HDV can be quite different from those of a diesel truck or bus . Better operator training was recommended by the SMEs to safely and effectively deal with the distinct failure modes of FE technology - equipped vehicles, including proper use of emergency propulsion modes designed to steer a disabled vehicle to the roadside. The general potential safety concern articulated fo r HHVs is the high pressure of the fluid system . However, the low number of in - service vehicles means that more time would be necessary to more thoroughly assess their safety performance . In the meantime, robust hydraulic line and accumulator tank inspecti on and maintenance schedules would minimize any safety risk for the limited existing fleets, as these appear to be the main potential points of failure. According to the SMEs queried, speed limiters in MD/HDVs have not led to safety issues so far. One SM E specifically recommended their adoption in tandem with driver training to improve fleet safety . The only potential safety concern they identified was unsafe passing of other vehicles . Although a suggested countermeasure would be for speed limiter - equippe d MD/HDVs to stay in lane and not pass, there are situations where passing at higher speed may be necessary. Idle reduction technologies such as auto start - stop and auxiliary power units have demonstrated FE benefits of varying levels without any reported safety hazards. SMEs disagreed on whether there is in fact any effect on safety performance, or only a potential effect on reliability . Further study with a larger sample size of users would provide more information on any potential risks . Aerodynamic components did not introduce any reported safety issues, although there is potential to interfere with preventative safety if the aerodynamic system makes vehicle components inaccessible for inspection and hazards are not detected in a timely manner . Remov able aerodynamic components that can be temporarily detached, folded, or tilted to allow inspection could address these potential secondary safety hazards . For components whose inspection is visual, transparent aerodynamic components (e.g., polycarbonate) is another countermeasure.94 4 SCENARIO HAZARD ANAL YSIS AND PREVENTION / MITIGATION STRATEGIES 4.1 Technical Approach to Hazard Analysis of FE Technologies and Fuels in MD/HDVs Technically, the event Risk (R) is defined as the product of a hazardous event probabilit y of occurrence (p) by its consequence severity (C). However, for lack of empirical safety performance data, the classic Risk Assessment Matrix (RAC) shown in Figure 4 - 1 below is not yet feasible for a safety analysis of specific FE technologies safety imp acts. Ideally, a hazard characterization and classic probabilistic hazard analysis of MD/HDV crashes attributable to or involving FE technologies and alternative fuels should be based on ample statistics derived from real world data. However, though severa l types of FE technologies have been introduced individually or in clusters (e.g., speed limiters, idle reduction, route selection using GPS and ITS) over the past decade, most have been adopted only recently , and have very slowly penetrated truck and bus fleets.

Figure 4 - 1 : A Summary Risk Assessment Matrix R anking and Prioritizing Hazard s 400 A best practice for cost - effective risk management is to prioritize the hazard level s by Risk ( which is the product of probability an d consequence) . 401 This enables appropriate allocation of resources for risk reduction measures to address those high consequence events that result in loss of life, injuries and /or greatest property damage. The Hazard Matrix schematic in Figure 4 - 2 400 Source: DOD MIL - STD - 882E. See latest update of DOD - MIL - STD - 882_E, Sy stem Safety Standard Practice, May 2012, at www.system - safety.org/Documents/MIL - STD - 882E.pdf 401 See for instance the ANSI - endorsed standards ISO 27001 - Risk Assessment and ISO 31000 (200 9) Risk Management - Principles and Guidelines95 indicates potential risk mitigation responses (from low to high ), based on combinations of event probability and consequence severity. Some risk levels related to vehicle operation can be transferred via insurance coverage ; while negligi ble risks are routinely accepte d as the cost of doing business . While there are currently numerous Federal and State laws and incentives for manufacturing and buying fuel - efficient vehicles, 402 there are as yet no auto insurance credits for better safety in opera ting vehicles with FE technolog ies that we could identify. The classic Hazard level ranking matrix in Figure 4 - 2 shows what types of hazards must be addressed versus those considered too improbable, unaffordable to control, or of negligible impact: most risk categories can be prevented or managed cost effectively through engineered controls, or with design or operational changes . The vertical axis corresponds to the Consequence severity, and the horizontal axis shows the freq uency of event occurrence.

Figure 4 - 2 : A Hazard Level Matrix Showing Ranked Event P robability and Consequence Severity . A preliminary hazard analysis (PHA), a probabilistic fault - tree analysis (FTA) , or failure mode and eff ect analysi s (FMEA) all require statistically meaningful information on single - point failures, or failure chain frequency of occurrence, and their respective severity of consequences. At present, the lack of statistical data on crashes attributable to a sp ecific category of FE technology, or a cluster thereof, or to alternative fuel use precludes either quantitative or qualitative hazard characterization and ranking. The literature review (Chapter 2) and focused interviews conducted with SMEs familiar with fuel efficiency technologies and MD/HDV fleet operations (Chapter 3) have also indicated that
402 See the DOE Alternative Fuels Data Center laws and Incentives at www.afdc.energy.gov/laws and www. afdc.energy.gov/laws/matrix/tech96 there is no statistically meaningful information causally linking crashes to any specific FE technology. Further, the introduction of new vehicle FE technologies and the integration of new or upgraded automotive subsystems (both FE related and unrelated), alternative fuels, and associated refueling infrastructure may lead to as yet unforeseen failure modes and failure chains due to greater complexity and to the “l earning curve” period . The NACFE 2011 Freight Efficiency Technologies Benchmark report 403 has evaluated the rate of adoption over time for six major FE technology clusters by 18 representative truck fleets, as shown in Fig. 2 - 12 . NACFE has also conducted in - depth benchmarking studies of the adoption benefits for specific FE technologies, such as tire pressure monitoring, anti - idling technologies, and 6x4 packages . However, MD/HDV fleet - wide penetration and operational experience with vehicles equipped with F E technologies to date with are still too modest to quantitatively modify the crash safety performance of the national MD/HDV fleet. Only a few FE equipment failures may be safety - critical, and their identification is only possible through realistic scena rio analysis and modeling, and/or through longer - term in - service fleet tests and evaluations, such as those performed by NREL 404 for hybrid electric buses, trucks and delivery vans. Some safety - critical failures may show up after considerable time, after a w arranty period or design life ends. T ypically, new products may be overdesigned with extra redundancies and safeguards since bad publicity after a major a failure with severe public safety impacts can lead to massive recalls, close a new production line, a nd potentially bankrupt affected operators and OEMs. The OEM engineers interviewed indicated that they design, build and integrate new FE technology and fuel subsystems into MD/HDVs for safe operability, and that CMV drivers are trained and certified to op erate them in a safe manner. Moreover, new fuel efficiency subsystems (e.g. hybrid drive, TPMS, aero - skirts) integrated into commercial vehicles are typically overdesigned to ensure their safe operation for the duration of the design life, and/or warranty coverage. Furthermore, the NHTSA/FARS and FMCSA/CSA databases do not include detailed information on vehicle FE technology involvement in crash reports. The 2007 FMCSA LTCCS report to Congress 405 showed that the large truck vehicle related relative contribut ions to crashes are smaller than driver - related crash causes, of which vehicle - related causes represent 10 percent . At present , n o quantitative risk ranking of safety hazards related to FEs and alt - fuels , or even a structured qualitative PHA is possible a t present due to: • The lack of statistical safety data of MD/HDV vehicle crashes linked to FE technologies . • Insufficient and only short duration experience of SMEs who provided inputs with actual crash or other safety mishaps for “clean fleets.”

403 See NACFE 2011 Benchmarking report and update at http://nacfe.org/wp - content/uploads/2012/09/NACFE 2012 - Benchmark - S tudy - Update - 062812.pdf and related in - depth FE technology benchmarking studies and barriers to adoption at http://nacfe.org/ 404 See www.nrel.gov/news/press/201 2/1987.html and www.nrel.gov/vehiclesandfuels/fleettest/publications_hybrid.html 405 See LTCCS FMCSA report to Congress at www.fmcsa.dot.gov/safety/research - and - analysis/report - congress large - truck - crash - causation - study97 • The l ack of statistical confidence to enable rank ing potential hazards by probability, consequence and overall risk level; • Li mited and sparse data in cited literature on hazardous incidents due to alt ernative - fuels operations, and /or fires due to rechargeable Lithium Ion batteries . • The SMEs consulted offered in Section 3 only limited available information and opinions on potential hazards and their top five safety concerns, based on their own experience with clean commercial MD/HDV fleets, or transit bus fleets. Cre dible hazard scenarios can be proposed and analyzed to provide insights into the worst - case consequence . A deterministic scenario - based risk assessment (RA) methodology was adopted, in which a “worst case” scenario and its consequence are assumed, and the potential prevention and mitigation options to reduce impacts (through compliance with safety regulations, applicable voluntary technical standards, or adoption of industry best practice) are explored . Some risk analysts object to this type of deterministi c risk assessment because it focuses on worst case scenarios with severe consequences, which are considered to be a rare occurrence. Prevention or mitigation of such “worst case” events is often costly and considered unduly “conservative.” 406 Nevertheless, both “best case” and “worst case” scenarios can be used as a tool to bound or scope possible risk levels, and can offer insights into engineered or operational procedures that could prevent or respond to hazards . Given the lack of hard data on highway safe ty impacts, the hazard scenarios rely on the literature findings and on the SMEs inputs (Chapter 3) based on their limited experience or qualified opinions. Consulting experts for their informed opinions regarding hazard identification and ranking is calle d the Delphi Approach . News and literature a ccounts of real crashes and accidents involving CNG trucks and buses, or hybrid and electric vehicles identified through Internet searches and related trade safety information were also used in the detailed scena rios below. Scenario s involving FE technologies, alternative fuels, and operator factors leading to a vehicle crash, fire, or explosion are illustrated . Each scenario is discussed below in detail in context, and can be supported by at least one reported a ctual incident, cited literature, or by SMEs inputs . Th is scenario analysis allows for identification of strategies to prevent and/or mitigate such hazardous occurrences . 4.2 Scenario Analysis of Safety Hazards identified by SMEs 4.2.1 Hazard A nalysis of CNG
- Fueled Trucks and Buses Cleaner CNG fueled MD/HDVs have been safely operated in the United States and worldwide since the early 19 80s with over 90,000 in use today. Public transit authorities have accumulated considerable experience with the safe operat ion of la rge CNG bus fleets over the past two decades, according to APTA 407 , such as Los Angeles Metro , which operates the largest (over 2200 ) urban fleet of CNG transit buses in the United States .

406 See postings at www.palisade.com/risk/risk_analysis.asp 407 See “Transit on the cutting edge of clean technology,” Sept 2012 at www.apta.com/resources/statistics/Documents/Trans it - Clean - Technology.pdf98 A recent FMCSA safety study of the commercial NGV fleet 408 cited the D OE/EIA 2010 inventory of 43,088 MD / HD V vehicles, including 21,510 urban transit buses, 7,466 heavy - duty trucks, 5,925 medium duty trucks and 8,187 vans. As CNG MD/HDV s are now being rapidly deployed, attention to safe operability and refueling is paramount . NGV America safety statistics 409 cite the safe and reliable in service operation of over 10,000 CNG fuel ed transit and school buses and shuttles, stating that 1 in 5 new transit buses are CNG fueled. An NGV A merica survey of over 8,331 NGVs showed they ha ve a better crash safety record than conventional counterparts, with a 31 percent lower crash rate, no fatalities and 37 percent fewer injuries . Of only 7 fire incidents noted, only one was due to the CNG fuel system failure. The strong cylinder tank survi ved intact in crashes, with no leakage or fire due to the automatic fuel release valve activated in case of excessive heat or pressure build - up. Powertech 410 noted that only 26 CNG cylinder failures occurred from 2000 to 2008 , and that the probability of a C NG vehicle cylinder failure is quite low , and that catastrophic ruptures are very rare. The events cited through 2008 (see Figure 2 - 4 and general discussion above) included : 5 failures due to mechanical damage, 12 due to environmental damage (exposure to t emperatures too hot or too cold), 8 leaks due to metal liner and 6 due to plastic liner failures; only 16 resulted in vehicle fires . Aftermarket conversions to CNG using steel (Type 1) cylinders were involved in 50 percent of these failures . The Powertech failure analysis also illustrated how CNG buses with Type 4 composite tanks mounted on the bus roof were damaged in collisions with low overhead barriers or tunnels. In these cases , the punctured tanks released the CNG, but did not burst, explode, n or igni te . Compliance testing with FMVSS 304 has reduced the number of deaths and serious injuries due to CNG leakage from tanks ruptured in crashes. Given the very few actual incidents either reported by fleet managers (in Chapter 3) or in the literature (Chapt er 2), safety h azards due to CNG tank failures in MD/HDVs could not be ranked by probability, consequence , severity , or overall r i sk level . O nly tank failures for CNG - fueled trucks are discussed in this scenario ; crashes of CNG tanker trucks delivering fue l to refueling compressor stations or industrial sites are omitted, since they are already subject to compliance with PHMSA hazmat regulations . Greater highway safety risk could potentially result from highways crashes of loaded CNG tanker trucks deliverin g fuel to refueling stations and compressor mishaps, but no such incidents were found documented in the literature . 4.2.1.1 Incidents of Vehicle Fire s or Explosion D ue to CNG Tank Rupture Several SMEs identified the potential for ignition or explosion scenarios due to pressurized ( 3 , 500 - psi ) CNG tank rupture, or to a leak or malfunction of the automated vent on the fuel tank as a risk concern in purchasing and operating CNG fueled trucks. The SMEs conjecture, rather than experience, was that the probability of su ch an event would be medium, but the

408 FMCSA Natural Gas Systems Safety Study, 2012 at http://ntl.bts.gov/lib/51000/51300/51334/Natural - Gas Systems - Tech - Brief - 508.pdf 409 See “How Safe are Natural Gas Vehicles?” at www.ngv c.org/tech_data/techbulletin2.html 410 See “CNG and Hydrogen Tank Safety, R&D and Testing,” Joe Wong, Powertech Labs, Inc., 12.10.2009, at www1.eere.energy.gov/ hydrogenandfuelcells/pdfs/cng_h2_workshop_8_wong.pdf99 consequence could be high. Tank failure either could occur due to a road crash, or due to accidental leaks or venting during refueling indoors or outdoors, followed by ignition. R ecent CNG tank failures documented in t he literature and i nternet illustrate potential hazards : • In Feb ruary 2011, a CNG explosion at Pierce Transit refueling depot (near Seattle) occurred during a CNG bus refueling (probably due to a compressor failure), destroying the bus . 411 • In Feb ruary 2012, in Statesboro, G eorgia, a university CNG bus caught fire and exploded when a small spark started a fire that reached the CNG tank, but the driver evacuated all passengers in time . Bus passenger fatalities and/or severe burn injuries could result from such an accident if timely evacuation were not possible. W orse consequences might result if such an event occurred on a busy road at rush hour, causing a multi - vehicle chain of fire or explosion s , and caus ing harm to passengers. According to industry best pract ices (standard NFPA 52) every CNG cylinder must be equipped with a pressure relief device (PRD) to safely vent the gas in the event of a vehicle fire, thus totally avoiding cylinder rupture. The explosion indicates that the PRD was not present, or malfunct ioned . These incidents suggest that both manufacturing standards, and in - use safety standards for vehicle maintenance and condition are needed to ensure that necessary safety systems (i.e., PRD) are in place. 4.2.1.2 Rupt ure of Degraded or Expired CNG T anks NHTSA has been conducting active research on CNG tank failures, to ensure safety under FMVSS 304 , "Compressed Natural Gas (CNG) Fuel Container Integrity." 412 FMVSS No. 304 and the ANSI NGV2 standard set minimum performance requirements for CNG containers used for fuel storage in motor vehicles. FMVSS 304 includes tank testing provisions which are necessary to determine whether a fuel storage system meets the performance requirements. Manufacturers ’ labeling must indicate if a tank ’s useful service life is 10, 15, 20 or 25 years . 413 FMVSS 304 requires that “ This container should be visually inspected after a motor vehicle accident or fire and at least every 36 months or 36,000 miles, whichever comes first, for damage and deterioration.” NGV2 414 also requires in - service visual CNG tank inspection every 3 years or 36,000 miles, and its destruction and disposal after its service life . Based on limited experience to date with CNG buses and trucks, some SMEs estimated that the probability of such failure events due to aging, degraded CNG tanks used beyond their design life could be Medium, but the consequences potentially High. When CNG tanks reach the end of their 15 - 25 years design life or service life, they should be decommissioned and replaced . There are reported explosio ns of expired or damaged CNG tanks

411 See incident at http://seattletransitblog.com/2011/02/28/breaking - gas - explosion - at - pt - facility 412 See B. Hennessey, Jan 2012, SAE/GIM presentation at www.sae.org/events/gim/presentations/2012/hennesseynhtsa.pdf 413 See www.ngvi.com/t ag/ngv2/ 414 See www.transecoenergy.com/pages/CNG_Tank.htm100 which remain in service, being unscrupulously resold through shops and online, e.g., on eBay ; though these claims have not been substantiated by a Gov ernment agency . 415 Robert Zalosh, a fire and explosions prevention expert from Fir e xplo, cited several tank explosion incidents involving degraded, damaged or expired CNG tanks. 416 A national inventory of all CNG tanks on trucks and buses could aid in enforcing proper tank end of life disposal . In addition, required NGV trainin g for all automotive mechanics who service NGVs could help to ensure that damaged CNG tanks are not placed back in service without the necessary inspection. 4.2.1.3 Prevention and Mitigation of CNG Tank Failure and Refueling Hazards The regulatory requirement of FMVSS 304 (CNG Fuel Container Integrity) cited above is for CNG tank inspection every 36 months, after a fire or reportable DOT accident, or the removal of a tank from service after its expiration date. Compliance with FMVSS 301 (Fuel System Integrity) an d FMVSS 303 (Compressed Natural Gas (CNG) System Integrity) 417

— which currently apply only to vehicles below 10,000 lbs GVW and to school buses regardless of weight

— could further enhance the safety of CNG fueled MD/HDVs if their domain of applicability were e xtended to Class 3 and above vehicles . The Clean Vehicle Education Foundation (CVEF) posts a long list of safety regulations, codes and standards applicable to CNG fueled vehicles, infrastructure and operations . 418 These include SAE, NFPA and ANSI pressur ized vessel voluntary consensus standards and recommended practices . The Foundation reviewed the limited calendar service life for ANSI NGV2 and FMVSS 304 NGV fuel containers , and developed a CNG tank Safety Training and Inspection program for owners/opera tors . 419 The f oundation also posted safe CNG tank refueling, decommissioning, venting, post - crash, and proper procedures and guidance to prevent high - risk venting scenarios 420 paying special attention to aftermarket conversions (see Figure 2 - 5 ) .

415 American Truck ing Association. 2009. Expanding ATA’s Safety Agenda Executive Summary www.truckline.com/Newsroom/Policy%20Papers/Safety%20Task%20Force%20Report.pdf 416 Zalosh, R. 2009. CNG and Hydrogen Vehicle Fuel Tank Failure Incidents, Testing, and Preventive Measures www.mvfri.org/Contracts/Final%20Reports/CNGandH2VehicleFuelTankPaper.pdf and postings at www.firexplo.com/ 417 See e - 49CFR571 for FMVSS at www.ecfr.gov/cgi - bin/text idx?c=ecfr&tpl=/ecfrbrowse/Title49/49cfr571_main_02.tpl 418 NHTSA. 2010b. Tire Pressure Monitoring System Tests For Medium and Heavy Trucks and Buses www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle%20Research%20&%20Test%20Center%20(VRTC)/ca/capubs/811314 .pdf 419 See www.cleanvehicle.org/technology/cylinder.shtml 420 Clean Vehicle Education Foundation. 2010. How Safe are Natural Gas Vehicles? www.cleanvehicle.org/committee/technical/PDFs/Web - TC - TechBul2 - Safety.pdf , Clean Vehicle Education Foundation. 2012. Fatal accident removi ng cylinder solenoid valve www.cleanvehicle.org/technology/ValveFatality.pdf101 CVEF industry b est practices to prevent and/or mitigate hazards related to vehicle tank or refueling infrastructure CNG leakage leading to potential fires and explosions include : adequate training of maintenance staff and operators, frequent inspections, emergency resp onse planning and preparedness, and engineered controls . The literature recommend s voluntary compliance with industry best practices, standards and guidelines for CNG tank failure and refueling hazard minimization , and avoidance measures . These include how to: • Provide methane gas and fire detectors both on - board the vehicle, and in depots and at fueling station. • Ensure that pressure relief devices (PRDs) are mounted on the CNG high - pressure tank and piping subsystem. • Provide a manual CNG shut - off valve fo r back up and to safeguard and isolate the fuel storage system from the engine. • Install fire extinguishers to respond to leaks and prevent or extinguish fires. • Safe vent CNG tanks for maintenance or replacement (using automated or manual venting) after a crash, and/or any piping and tubing that leaked. • Ensure compliance with SAE best practices for CNG MDHD trucks, including SAE J2406 (Recommended Practices for CNG Powered Medium and H eavy - D uty Trucks), SAE J2343 (recommended practices for LNG - powered h eavy - d uty t rucks) . • Comply with fire safety NFPA 52 421 and NFPA 57 422 codes applicable to any vehicle and/or facility that refuel s CNG or LNG vehicles . • Install engineering controls including: methane detectors, visual/audible alarms, and other safeguards to preve nt ignition and vehicle fires in NGV refueling depots . These are recommended over reliance on process controls, such as manually opening doors or vents whenever an NGV is brought into a shared indoor facility . 4.2.2 Safety of LNG
- F ueled MD / HDVs and Refueling Sys tems Cryogenic Liquefied Natural Gas (LNG) use as a transportation fuel is accelerating. As discussed in Chapter 2, LNG is better suited to over the road short haul HD operations than CNG (1 gal o f diesel has the same energy contents as 1.67 gals LNG, but 135 scf CNG ) . There are few refueling stations at present; these mostly are operated for corporate or city fleets . Currently there are only 6,000 LNG fueled vehicles in the United States , mostly transit buses in Dallas and Austin, TX; El Paso and Phoenix, AZ; and Los Angeles and Orange County, CA. Between 2010, the p orts of L os Angeles and Long Beach will replace 800 drayage trucks with LNG trucks, with 219 deployed by December 2012. 423 Waste Management, Inc. has operated an LNG fueled refuse truck fleet for years in CA and PA, and just added its 1000 th LNG truck to the fleet

421 National Fire P rotection Association. 2010. NFPA 52: Vehicular Gaseous Fuel Systems Code www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=52 422 National Fire Protection Association. 2002. NFPA 57: Liquefied Natural Gas (LNG) Vehicular Fuel Systems Code www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=57 423 See CARB, May 12, 2012, “Heavy Duty Natural Gas Truck Replacement Program” at www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration/arravt045_ti_white_2012_ o.pdf102 ( Figure 5 - 3 ) . 424 NREL has conducted several evaluation s of the Waste Management , Inc. LNG truck fleet, showing emerging design and operational improvements over time. There are a few comm ercial producers of LNG and some distribution firms (mostly via LNG tanker trucks) that supply LNG fueling stations. LNG Dedicated tanker truck operators include: Tri - Mac, Transgas, Southeast LNG, J.B. Kelley, and L.P. Transportation. The National Petrole um Council (NPC) Future Transportation Fuels (FTF) recent studies included a qualitative safety evaluation of LNG as an emerging transportation fuel, with associated risks relative to petroleum discussed in the literature and Chapter 2 . 425

Figure 4 - 3 : Refueling a Waste Management LNG T ruck 426

424 See 2001 NREL report at Waste Management's LNG Truck Fleet Alternative Fuels Data at www.afdc.energy.gov/pdfs/waste_lng_final.pdf and www.wm.com/about/press - room/2011/20110712 - wm - adds 1000th - natur al - gas - truck.jsp 425 National Petroleum Council. 2012. An Initial Qualitative Discussion on Safety Considerations f or LNG Use in Transportation www.npc.org/FTF_Topic_papers/19LNG_Transportation.pdf103 Th is NPC white paper on LNG safety cited the excellent safet y record for LNG transportation. There were only 20 - 30 over - the - road incidents since 1971 that involv ed road crashes; less than half of which le d to spills , and only one resulted in a fire with driver injury . In one crash , the LNG vessel on a crashed tanker truck maintained integrity when diesel tanks of the other vehicle caught fire . Potential s afety hazards include cryogenic liqu id burns from drivers contacting spill ed LNG and the potential for fire or explosion . However, engineered system safeguards , such as double walled steel container tanks with insulation, PRDs, and inspections to prevent steel tank embrittlement and cracking , reduce the risk of a boiling liquid expanding vapor e xplosion ( considered a worst - case scenario in the event of a fire or crash). M ultiple safeguards are used for refueling equipment and procedures. Fire suppression equipment and training for maintenance personnel and emergency responders c ould mitigate the consequences of such an LNG truck mishap. 4.2.3 Flammability of Lightweighting M aterials and T oxicity of Burning Byproducts As discussed in Chapter 3 .2.9 , s ome SMEs raised potential safety concerns regardi ng the fire safety and flammability of some materials used for automotive light - weighting. Although there is little to no actual experience to date, the SMEs conjecture was that the probability of such occurrences, assuming larger scale deployment of light er MD/HDVs, could be low to medium, but a fire related consequences could be medium to high . Various carbon - fiber reinforced polymer s (CFRP), resins, and plastics are typically more fl ammable than steel , and lighter weight metals (high performance steels, aluminum and titanium) . Use of CFRP and glass fiber composites in phenolic, with high stiffness to weight ratios, are some of the emerging structural materials used for vehicle mass reduction . Other material systems include honeycomb sandwich structures, high performance steels, and titanium and magnesium alloys to achieve “mass compounding” benefits that reduce overall MD/HD verse weight in order to enhance fuel efficiency. NHTSA held several workshops to examine the relationship between vehicle mass and size and crash safety in 2013 427 and 2011. Although lightweighted vehicles may offer improved maneuverability and shorter stopping distance, they could also result in reduced cras h survivability in certain crash scenarios and /or in vehicle fires. While there is no supporting data in the literature regarding the crashworthiness of light - weighted Class 2b to 8 vehicle s , there are some general safety concerns about the materials . Knowledge of fire and shatter hazards associated with the composites used in aircra ft and marine applications can be transferrable to MD/HDV composite applications . The fire safety and health hazards of byproducts from burning composites include the potential release of volatile organic compounds, toxic microscopic fibers, and combustio n products were a

426 Wall Street Journal, May 23, 2012, “Will truckers ditch diesel?” at http://online.wsj.com/article/SB10001424052702304707604577422192910235090.html#printMode 427 See mass - size - safety May 2013 workshop presentations at www.nhtsa.gov/Laws+&+Regulations/CAFE+ - +Fuel+Economy/NHTSA+Vehicle+Mass - Size - Safety+Workshop ; and the 2011 workshop transcript at www.nhtsa.gov/Laws+&+Regulations/CAFE+ - +Fuel+Economy/NHTSA+Workshop+on+Vehicle+Mass - Size Safety104 secondary concern . Toxic fire byproducts, dispersal, and inhalation of fine fibers pose health hazards to emergency responders and bystanders. 428 Carbon fiber and epoxy materials ignite easily and burn rapidly . Smoldering or burning compos ite s produce toxic smoke containing irritants, combustion gases (HCl, HBr, NO2), soot particles and sharp fibers, which in turn can cause choking, cough and disorientation, as well as long - term health problems following exposure. 429 Passive fire protection c oatings such as Vermitex and fire suppression equipment in the cab could prevent and mitigate flammability hazard and toxicity of by - products for new MD/HDV materials . However, fire safety and environmental health issues for specific lightweighting tractor cab and trailer bed materials would benefit from further study . Also, fire prevention and suppression best practices from light - weighted composite - rich aircraft skins and seating may be useful, if proven to be cost - effective. 430 Brittle failure, or s hatter ing of composite body panels in a crash - even without any fire - may also pose hazards from the release of fine particulates that irritate skin and lungs, and could require EMTs to wear respirators for protection . Materials Safety Data Sheets (MSDS) for spe cific fuel efficient lighter weight truck and trailer materials could help in the evaluation of the potential severity of a crash with or without resulting fire. A 2007 Volpe Center study for NHTSA that developed a safety roadmap for future PCIV s 431 that in cluded both structural and fire safety is also relevant to MD / HD V lightweighting materials options . Plastic foam filler used in interior seating and door padding could also release toxic volatile organic compounds and carbon monoxide in a crash - fire. 4.2.4 Safet y P erformance of Single Wide Base Ti res and Low - Rolling Resistance T ires Wide base single tires, also called “super - singles,” and LRRs are being increasingly adopted by MD/HDV fleets, as discussed in Chapter 2 .7.2 . In Chapter 3 .2.7 we reported that s ome SME s perceived an increase in stopping distance or reductions in stability and control on slick highways when using LRR and/or wide base tires. In their opinion, th is h azard p robability could be m edium but the c onsequence potentially m edium to h igh. As in dicated in Chapter 2 .7.2 , this research identified no studies that document reduced safety performance for either LRR or wide - base tires . Indeed, EPA’s testing of conventional and LRR

428 Gandhi, S. 1999. Postcrash Health Hazards from Burning Aircraft Compo sites www.aviationfirejournal.com/aviation/library/VOL6 - Hazards.pdf 429 Flight Safety Foundation. 2008. Downwind Debris http://flightsafety.org/asw/sept08/asw_sept08_p40 - 43.pdf?dl=1 430 Gandhi, S., & Lyon, R. E. 1998. Health Hazards of Combustion Products Fro m Aircraft Composite Materials www.tc.faa.gov/its/worldpac/techrpt/ar98 - 34.pdf 431 Brecher, A. 2007. A Safety Roadmap for Future Plastics and Composites Intensive Vehicles www.nhtsa.gov/DOT/NHTSA/NVS/Crashworthiness/Vehicle%20Aggressivity%20and%20Fleet%20Compatibility %20Research/810863.pdf105 Class 8 tractor and trailer tires found no significant correlation betwe en the snow traction rating and the coefficient of rolling resistance . 432 Since a LRR wide base tire replaces twin tires , a high - speed blowout on the road of a wide base tire , especially for heavy loads, could potentially affect the vehicle balance and stabi lity at higher speeds . However , literature from the EPA’s SmartWay Program indicates that wide base tires can improve the stability and control of combination trucks and tank trailers by allowing the tank to be mounted lower . 433 A NHTSA study of decreased t ire pressure impacts on safety indicated that tire pressure monitoring is an important safety factor . 434 Although the NHTSA crash files did not contain direct evidence that points to low tire pressure as the cause of any particular crash, low tire pressure was considered a possible factor in crashes due to loss in traction and blowout failures of underinflated tires, as well as increased stopping distance . The use of TPMS for wide base tires (or with any MD/HDV tires) may prevent under - inflation and reduce t he risk of crashes due to flat tires and blowouts. 4.2.5 Longer Combination Trucks . . S everal types of LCV configurations with extra length and gross vehicle weight (GVWR) ranging from 80,000 to over 120,000 lbs. , have been allowed to operate (with special dri ver training requirements and varying restrictions) in 23 States to date ( Figure 4 - 4 ) . Operation is permitted on some interstate, rural two - lane, or city roads and interchanges. Advocates for Highway and Auto Safety strongly opposed lifting the 1991 restri ctions on LCV highway operations, citing NHTSA, IIHS , and UMTRI data. 435 The American Trucking Association (ATA) supports seven limited reforms to current truck size and weight regulations that would allow LCVs in order to increase the productivity, fuel eff iciency, reduce truck traffic and environmental emissions . 436 The Owners Operator Independent Drivers Association opposes LCVs 437 due to several safety concerns that may contribute to LCV crash hazards in mixed vehicle traffic, especially on urban freeways and interchanges: • Off - tracking at both low and high speeds, when tractor trailers turn in a curve or at intersections and encroach into shoulders and adjacent lanes, endangering both parallel and/or oncoming traffic . A t low speeds, rear wheels track insi de th e path of the front

432 See “Snow Traction Performance of Low Rolling Resistance Drive Tires for Cl ass - 8 Tractor Trailers,” SAE Paper 2012 - 01 - 1918 at http://papers.sae.org/2012 - 01 - 1918/ 433 See www.epa.gov/smartway/documents/partnership/trucks/partnership/techsheets - truck/EPA - 420 - F10 - 041.pdf 434 See Tire Pressure Monitoring Final Rule (Part III - Safety problem) at www.nhtsa.gov/cars/rules/rulings/tirepresfinal/safetypr.html 435 See 2005 Factsheet “The Dangers of Large Trucks” at www.saferoads.org/issues/fs - trucks.htm 436 See “ATA Summary of Truck Size and Weight Studies” at www.transportationproductivity.org/Studies/ATA_Su mmary_of_TruckSizeandWeightStudies.pdf and www.truckline.com/AdvIssues/HighwayInf_Fund/Documents/Propo sed%20Reforms%20to%20Federal%20Truck% 20Size%20and%20Weight%20Limits.pdf 437 See LCV issues at www.ooida.com/OOIDA Foundation/issues/LCVs.shtml106 wheels while at high speeds they track outside the path, with widths varying with consist length and weight. • Larger and heavier loaded LCV big rigs cause more and costly damage to infrastructure (pavements, bridges, and shoulders) that is not designed to sustain such loading, even though operators distribute the load over more axles. • Trailer sideways sway and jack - knifing motion on open road (even when not windy), which is amplified rearward for longer LCVs like triples and causes encro achments into adjacent lanes and traffic, especially in response to sudden steering. • Lower stability of LCVs, which are more prone to rollover due to connections between the second and third trailer. • Longer braking and stopping distance that can cause cras hes in sudden braking, and require special and more frequent inspections and brake adjustments. • Difficulties LCVs have when accelerating and merging with traffic at interchanges, due to the mismatch in speed and acceleration abilities of LCVs relative to o ther vehicles. • Difficulty of LCVs in maintaining speed on inclined roads, both climbing and for down grade, compared with other vehicles. • Hazards of splash and spray from LCVs to vehicles when passing long LCVs in rainy, fog, windy, or snowy conditions (du e to blinding spray on windshields, and side - winds). • Difficulty of LCVs parking in rest areas and at weigh in motion (WIM) stations .

Figure 4 - 4 : Three Types of LCV C onfigurations 438

438 Source : www.usroads.com/journals/rej/9708/re970806.htm107 The SMEs interviewed in Chapter 3 believed that potential LCV hazards have a low probability; but consequence severity could be medium to high . However, several studies on the relative safety of LCV operations that compared to other trucks that were conducted over the past 20 years indicate that s uch hazard assessment remains inconclusive because of insufficient data, and the small number of LCVs, as well as no causal linkage details in the crash data collected. 439 The American Automobile Association ( AAA ) has conducted pilot studies in five States that allow LCV operations and determined that analysis is not possible due to inadequate detail in crash data collection, and lack of reliable data . California DOT (Caltrans) conducted LCV field tests in 1983 on a variety of roads and diverse speeds and de termined that problems outweigh the benefits. 440 The FHWA has conducted several Truck Size and Weight studies, including a 2000 scenario description of LCV nationwide traffic 441 for the North American Free Trade Agreement ( NAFTA ) , and a safety evaluation that required aggregating 6 years of crash data (1995 - 99) to get meaningful statistics for a safety comparison . These FHWA studies concluded that data were not adequate to make reliable risk predictions, and that fewer LCVs on the roads would reduce the overal l travel risk exposure more than reducing truck crashes. 442 The most comprehensive 2009 safety analysis of LCVs 443 reviewed multiple Over - Size/Over weight (OS/OW) large truck crash data sets (TIFA/UMTRI, FARS, weigh station data - WIM, LTCCS, TRB) and concluded that as commercial vehicles become larger and heavier, crash rates decrease, but crash severity increases. However, due to lack of consistency and quality in crash data collections, findings on LCV relative safety are inconclusive. The most recent cost - b enefit reassessment of LCVs conducted by the University of Wisconsin National Center for Freight and Infrastructure Research and Education ( CFIRE ) in 2012 reviewed the literature for LCV pros and cons . It found as many claims for safer LCV operations, as f or less safe impacts , and concluded that the benefits outweigh costs and warrant expanding nationwide LCV operations. 444 In a potential ly worst case , high consequence scenario, multi ple vehicle crashes might occur on a two - lane highway when small vehicles ar e trying to overtake a long, slow - moving triple - trailer LCV - especially in low visibility hazardous weather - and crash with oncoming traffic, causing multiple fatalities, injuries and vehicle damage. No such worst case , pile - up crash scenario was
439 See AAA Foundation for Traffic Safety, “Longer Combination Vehicle Safety Data Collection,” 2000, at https://www.aaafoundation.org/sites/default/files/lcv.pdf 440 See CALTRANS Longer Combination Vehicles posting at www.dot.ca.gov/hq/traffops/trucks/exemptions/lcv.htm 441 See Chapter III, Scenario Descriptions at www.fhwa.dot.gov/reports/tswstudy/Vol3 - Chapter2.pdf 442 See at We stern Uniformity Scenario Analysis
- Chapter 7 Safety : www.fhwa.dot.gov/policy/otps/truck/wusr/chap07.htm 443 “ A Synthesis of Safety Implications of Oversize/Overweight Commercial Vehicles” by D. S Turner et al., University Transportation Center of Alabama (UTCA) report 07115, June 2009 at http:// utca.eng.ua.edu/files/2011/10/07115 - Final - Report.pdf 444 Adams, T., Kleinmaier, D., Marach, A., Helfrich, G., Levine, J., & Bittner, J. 2012. Longer Combination Vehicles: An Estim ation of their Benefits and Public Perception of Their Use www.wistrans.org/cfire/.../CFIRE_05 - 01_Final_Report.pdf108 found in a 2003 NHTSA/NCSA study of LCV crash types 445 ( see Table 15a, based on 1996 - 99 crash data). Countermeasures for potential LCV hazards , including both prevention and mitigation , could include improved driver training and certification, restricted road operatio n, mandated safety appliances (antilock brakes ( ABS ) , electronic stability control ( ESC) ) and automated trailer steering (ATS) , which enables steerable multiple axles for imp roved LCV stability and control, potentially eliminat ing or reducing sway related hazards. 446 4.2.6 Aero dynamic C omponents Aerodynamic components include a range of devices mounted onto a vehicle body , including those certified by the EPA SmartWay program 447 as FE technologies : • trailer gap reducer and trailer side skirts (used in combination wi th one another); • trailer boat tail and trailer side skirts (us ed in combination with one ano ther) ; • advanced trailer end fairing; and • advanced trailer skirts. For combination trucks, these components include cab extenders, trailer skirts, boat tails, and s treamlined mirrors and bumpers. As discussed in Ch apter 2, up to two - thirds of long - haul tractors and one - sixth of trailers in the United States are equipped with some aerodynamic FE technologies . S ome SMEs interviewed were concerned with potential incide nts of aerodynamic components detac hing while the vehicle traveled on a busy highway or urban roadway . Although trucks are more likely to strike stationary objects that damage a fairing while off - highway, e.g., at a loading or transfer facility, the maximu m severity of a detachment incident would be on - highway at high speed . In a worst case high - consequence scenario, a multiple vehicle crash could occur if a small vehicle trailing a combination truck on a highway was struck by detached aerodynamic fairings . In such a scenario, the detached fairing could penetrate the windshield of a trailing vehicle, leading to fatalities, injuries, and vehicle damage. T o date there are no known examples of such incidents reported in the literature. Thus, up to now the proba bility of occurrence for such detachment incidents appears to be very low . T here is no a priori reason to expect that large scale adoption of aero devices on Class 8 tractor - trailers will lead to a higher probability of occurrence for highway fairing detac hment incidents and potentially resulting crashes , though

– in principle

– the probability of individual aero detachment failures could scale to the number of devices deployed . Since aerodynamic fairings are designed to minimize weight, with typical trail er skirts weigh ing approximately 200 - pounds, they are unlikely to cause severe primary damage to other enclosed

445 See Report No. DOT HS 809 569 June 2003 , An Analysis of Fatal Large Truck Crashes at www nrd.nhtsa.dot.gov/Pubs/809 - 569.pdf 446 See Drastic productivity gain for Large Truck Operations with Automated Trailer Steering, 2009 at www.engr.sjsu.edu/media/pdf/res/coe_res_facdev_grant_symp_ 040309_tsao_ppt.pdf 447 See www.epa.gov/smartway/technology/aerodynamics.htm109 (i.e., non - motorcycle) vehicles on the highway in a detachment scenario . However, under special circumstances the resulting debris could result in vehicle crash hazards from avoidance maneuvers by nearby drivers . While early designs of underbody fairings tended to be monolithic and were prone to snapping in a bottoming - out collision with a curb or railway crossing, newer designs employ composite m aterials ( Figure 4 - 5 ) and are capable of flexing up to 90 degrees. 448 Videos of various skirts depict the vehicle being driven over 2 - 3 foot tall snow banks and curbs without breaking or detaching the skirt. 449 In a rear - end collision with a boat - tail equippe d vehicle, the lower panel of the boat tail may be vertically aligned with the windshield of cab - over trucks, buses, or passenger vans . 450 Depending on the boat tail panel construction, a worst case crash scenario c ould involve penetration of the windshield and possibly fatal injuries to the trailing vehicle’s occupants . However, no reported incidents of this type could be documented by our literature and Internet search .

Figure 4 - 5 : Trailer Skirt Made From Resilient Composi te Material 451 International research sources reviewed and experience abroad 452 , 453 , 454 , 455 , 456 , 457 suggests that covering the cavity between the front and rear wheels of MD / HDVs can provide a safety benefit

448 Freight Wing Incorporated. 2011. Aeroflex www.freightwing.com/aeroflex.php 449 Golsch, K. 2012 . HD Vehicle Fuel Economy Improvements through Aerodynamic and Front End Airflow Technological Advances 450 Patten, J., Poole, G., Mayda, W., & Wall, A. 2010. Trailer Boat Tail Aerodynamic and Collision Study www.tc.gc.ca/eng/roadsafety/safevehicles - motorcarriers - environment - boat - tails - 1307.htm 451 Freight Wing Incorporated. 2011. Aeroflex www.freightwing.com/aeroflex.php 452 SWOV

– Dutch Road Safety Research Institute. 1996. Closed Sidegua rds on Trucks: Less Fuel Consumption for Trucks, Safer Feeling for Vulnerable Road Users 453 Cookson, R., & Knight, I. 2010. Sideguards on heavy goods vehicles 454 Globe and Mail, Scrapped Canadian study found early promise for safer truck design, www. theglobeandmail.com/news/national/scrapped - canadian - study - found - early - promise - for - safer - truck design/article10600215/110 in side - impact collisions with non - motorists , such as bicycli sts and pedestrians , by reducing the likelihood of side underrun by the rear wheels . For example, the fraction of fatal side - impact collisions between bicyclists and trucks decreased 61 percent in the U.K. following a national implementation of cavity - cove ring sideguards on heavy trucks . 458 While sideguard implementation on U.S. trucks is nearly nonexistent, 459 d ecades of both aerodynamic and non aerodynamic sideguard implementation on trucks in the UK , 460 EU , 461 Japan, and Brazil raise the question of whether Nor th American truck skirts designed for aerodynamics and fuel economy could also potentially reduce the severity of under - ride crashes with non - motorists. At least one North American aerodynamic truck skirt manufacturer, Laydon Composites, already claims tha t its sideskirt meets the European lateral under - ride protection standard. 462 A 2013 National Research Council Canada study funded by the Transport Canada EcoTechnology program 463 examine d the level of side underride protection potentially provided by three c ommercially available aerodynamic trailer skirt models. 464 T he preliminary 2010 NRC Canada report 465 concluded : “The effectiveness of the sideguards on heavy vehicles has been demonstrated by a UK study . ” Another potential safety hazard scenario identified b y SMEs as result of aerodynamic fairings adoption is the potential for making vehicle underbody inspection more difficult . The highest consequence scenario would be a failure to detect safety - critical vehicle issues, such as deficient brakes, leading to su bsequent on - road failure . If brakes were to fail, a severe crash could result. However, the likelihood of this scenario was considered by SMEs to be low . No cases of inspection oversights that have caused subsequent crashes are known to be explicitly linke d to aerodynamic components . (Of course, if an inspection fails to identify an existing issue that causes a later crash, this data may simply not exist.) However, interviews with truck mechanics and maintenance staff at a major fleet suggest that aero com ponents do not hinder necessary

455 Riley, B. S., Penoyre, S., & Bates, H. J. 1985. Protecting Car Occupants, Pedestrians, and Cyclists in Accidents Involving Heavy Goods Vehicles by Us ing Front Underrun Bumpers and Sideguards http://trid.trb.org/view.aspx?id=237955 456 Lambert, J., & Rchnitzer, G. 2002. Review of Truck Safety: Stage 1: Frontal Side, and Rear Underrun Protection 457 I Knight et al. 2005. Integrated Safety Guards and Spray Suppression -- Final Summary Report at www.roadsafetyobservatory.com/Evidence/Details/11356 458 Ibid. as 446 459 Limited municipal pilot deployments totaling approximately 40 vehicles have taken place in Portland, OR and Boston, MA since 2010, in addition to an unf unded sideguard mandate in Washington, D.C. These pilot programs are too recent and small - scale to have produced statistically significant national crash data. 460 Riley, B. S., Penoyre, S., & Bates, H. J. 1985. Protecting Car Occupants, Pedestrians, and Cyclists in Accide nts Involving Heavy Goods Vehicles by Using Front Underrun Bumpers and Sideguards http://trid.trb.org/view.aspx?id=237955 461 European Union. 1989. European Coun cil Directive 89/297/EEC http://eur lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31989L0297:EN:HTML 462 National Research Council. 2010a. Technologies and Approaches to Reducing the Fuel Consumption of MD/HD Vehicles www.nap.edu /openbook.php?record_id=12845&page=R1 463 www.tc.gc.ca/eng/programs/environment - etv - menu - eng - 118.htm 464 Globe and Mail, Scrapped Canadian study found early promise for safer truck design, www.theglobeandmail.com/news/national/scrapped - canadian - study - found - early - promise - for - safer - truck design/article10600215/ 465 Patten, J.D. and Tabra, C.V. Side Guards for Trucks and Trailers Phase 1: Background Investigation, 2010. www.worldcat.org/title/side - guards - for - trucks - and - trailers - phase - 1 - background - investigation/oclc/797259567111 access. 466 In most European and Asian countries that adopted aerodynamic fairings as standard equipment on MD/HDVs normally present during inspections, access was not impeded. Clean carrier truck fleets, which are early adopt ers of aerodynamic packages, all demonstrate d superior safety performance based on FARS and MCMIS databases versus conventional carriers (see Chapter 4) . Moreover, the overall crash rate of trucks has not increased over the past decade , even as the deploym ent of aerodynamic devices has greatly increased . T o further reduce the likelihood of this scenario , potential c ountermeasures for inspection interference could include the use of mirrors by vehicle inspectors for inspecting certain items instead of crawl ing under the vehicle , making f airings removable, p roviding access hatches, or using hinged designs that provide on - demand access for inspectors . For visual inspection, certain fairings or wheel covers could also be made transparent. 4.2.7 P otential Fires from O verheated EV/PHEV Battery Longer - term experience with the use of high performance lithium ion batteries (LIB) in rechargeable energy storage systems (RESS) has accumulated from several thousands of advanced hybrid electric and electric transit buses and s huttles . By 2013, o ver 11 percent of transit bus fleets were hybrid and electric and more on order, according to APTA . Large transit agencies with safety operational experience include t he New York MTA operating over 1600 hybrid buse s , and the Washington M etrobus and King County DOT with hybrid fleets of over 600 buses each . This operational fleet experience offers safety “lessons learned” relevant to emerging commercial HEV/EV/PHEV counterparts . LIBs may pose potential risks due to thermal runaway when ove rheated or explosion and fire when the cell is ruptured . Flammable lithium and vented hydrogen or oxygen may initiate and sustain fires, and corrosive or toxic electrolyte could leak if the battery is breached . Although there are very few documented fire i ncidents in hybrid - electric buses to date and some SMEs cons idered that although this h azard probability w as l ow , the y believed the c onsequence severity could be m edium to h igh . Therefore, we document ed reported incidents below to provide the context for s uch a scenario. U.S. hybrid and electric transit buses models deployed and featuring LIBs integrated in high power and capacity RESS include : the Daimler Bus NA Orion VII, the DesignLine EcoSaver IV, the El Dorado National Axess, Gillig HEB models with Al lison dual - mode compound split propulsion, North America Bus Industries (NABI) diesel electric with ISE/Bluways ThunderPower, the Proterra composite electric or fuel cell buses with TerraVolt and Altair Lithium Ion Titanate (LTO) LIBs, and the New Flyer Xc elsior. The Orion VII diesel - electric hybrid buses with A123 Lithium Iron Phosphate ( LiFePO4 ) batteries 467 have been in service since 2007, and have been documented as being both energy efficient and environmentally friendly . 468 These batteries have greater energy density and power and are 3,000 pounds lighter than the previously used lead acid Orion battery packs, thus 466 Navistar. 2012. Aerodynamic and Tire Technology Adopter Interviews 467 See www.a123systems.com/solutions - transportation.htm 468 See TRB/TCRP Report 132, “Assessment of Hybrid Electric Transit Bus Technology,” December 2009, www.trb.org/Main/Blurbs/Assessment_of_HybridElectric_Transit_Bus_Technolog_162703.aspx and “ BAE/Orion Hybrid Electric Buses at New York C ity Transit: A Generational Comparison (NREL/TP - 540 - 42217).”112 improving bus fuel economy . They also have a stated six - year design life with lower operating and lifecycle costs. The BAE’s “next generation HybriDrive” may enable more flexible modular RESS configurations with electronically - controlled cooling and APU (fuel cells or other options) to be placed on the roof for easy access and maintenance , for fuel cell hybrid - electric buses. BAE’s HybriDrive 469 is also compatible with other hybrid and electric bus platforms and RESS options: the New Flyer Industries Xcelsior (XDE40) 40 - foot diesel HEB also uses the BAE HybriDrive with LiFePO4 batteries (from Lithium Technology Corporation). The LIB delivers 200 kW peak power and is cooled with forced air. The Washington Metro Area Transit Authority (WMATA) received 152 such Xcelsior buses in 2011 and ordered 95 more in 2012 for 2013. 470 Information on LIB failures and maintenance issues can also be found in NREL evaluations of hybrid and electric transit bus fleets upgraded with different LIB chemistries, which are operating in many U.S. cities. 471 , 472 These reports evaluate hybrid and electric bus fleets such as the New York City MTA’s BAE Orion diesel - hybrid bus f leet, Long Beach Transit’s gasoline electric hybrids, King County Metro’s Allison hybrid - electric buses, and Knoxville Area Transit’s Ebus electric buses and trolleys . For instance, the NREL multi - generational comparison of Orion/BAE hybrid - electric buses operating in the New York City MTA’s transit fleet 473 identified the key LIB performance, durability, and safety improvements needed for transit reliability, availability and durability. 474 On October 28, 2011, NHTSA’s Office of Defect Investigation issued a safety recall and corrective modifications or replacement of LIBs in Daimler Orion VII hybrid - electric buses. After several incident investigations due to accumulation of debris and moisture that potential ly breach ed electrical isolation , 475 1,300 Orion VI I hybrid buses with the BAE HybriDrive and RESS using A123 LiFePO4 batteries (manufactured in November 2008), and some earlier 2006

– 07 models retrofitted with LIBs were recalled to replace the battery modules on the bus roof. The BAE Systems HybriDrive 476 integrated a LiFePO4 battery chemistry based on its superior thermal stability, energy capacity, and operational safety , as well its modular, compact, lightweight design, and long er cycle life (over 6 years) . Even t hough the roof placement did not require active battery cooling it allowed the debris and moisture accumulation to cause potential short - outs and fires.

469 See www.hybridrive.com/ 470 See news at www.newflyer.com/index/2012_08_ 07_wmata_additional_order 471 See transit hybrid fleet reports posted at www.afdc.energy.gov/afdc/fleets/transit_experiences.html?print 472 See postings listed at www.afdc.energy.gov/afdc/fleets/transit_experiences.html 473 See “As Hybrid Buses Get Cheaper, Cities Fill Their Fleet,” New York Times , October 22, 2009, www.nytimes.com/2009/10/22/automobiles/autospecial2/22BUS.html?_r=1 474 See Clean Air Initiative: Infopool
– Hybrid Bus postings at www.cleanairnet.org/infopool/1411/propertyvalue 17735.html#h2_5 475 See Orion 7 Hybrid Bus Recall at http://recallcast.com/ recalls/2011/oct/28/daimler - buses - north - america - inc electr - 11v523000/ and at w ww.safercar.gov and http://recallcast.com/recalls/tag/orion/ 476 See www.hybridrive.com/hybrid - transit - bus.asp and www.hybridrive.com/lithium - ion - energy - storage system.asp113 This recall affected more than 1,600 Orion buses operating in New York City. The 2011 Orion VII safety recall has already affected many urban t ransit fleets in the United States and contributed to Daimler’s discontinuing the manufacture and marketing of Orion VII hybrid buses in the United States and Canada in April 2012. 477 The New Flyer manufacturer of Xcelsior buses, which also use the BAE Hybr iDrive RESS with A123 LIBs, notified NHTSA in March 2012 that it was recalling them to correct a similar RESS that could cause a LIB short and pose fire hazards . A total of 47 hybrid Xcelsior Metrobuses in the Washington, DC, area were also pulled from ope ration for inspections and corrective retrofits of LIBs by BAE Systems. 478 To date, both the incidence and severity of hybrid and electric bus safety incidents involving LIBs overheating, degassing, or having electrical short - out incidents are very low. On ly 10 similar incidents have occurred in the United States and Canada in the past decade out of more than 2,200 operating hybrid buses, with no resulting fatalities or injuries. Although hybrid and electric delivery trucks and vans in cities have similar duty cycles , centralized maintenance , and scheduled recharging to transit buses, long - haul trucks experience more demanding battery charge/discharge duty cycles . Potential hazards for this application could include the battery overheat ing or fail ing sudde nly in severe weather condition, potentially causing fires or crashes. 4.2.7.1 Electrical Hazards Prevention and Mitigation After a Chevy Volt fire and defect investigation, 479 NHTSA held a technical workshop on electric vehicle safety 480 (May 2012). I n cooperation with the National Fire Protection Association (NFPA), issued an “Interim Guidance for Electric and Hybrid Vehicles Equipped with High Voltage Batteries ” 481 , to assist owners/operators, first responders, and towing/recovery operators. The Guidance is applicab le to all hybrid and electric vehicles, including MD/HDVs . A t the May, 2012 Electric Vehicle Safety (EVS) workshop several presenters discussed the potential hazards specific to h eavy - d uty hybrids . 482 For instance, the high voltage cables and

477 See www.news channel6now.com/story/17736988/daimler - buses - reconfigures - operations - in - north america?clienttype=printable 478 See news item at washingtonexaminer.com/article/416416 479 PE11037; www odi.nhtsa.dot.gov/owners/SearchResults?searchType=ID&targetCategory=I&searchCriteria.nhtsa_ids=PE11037 480 See postings for May ’12 workshop and Jan ’12 Interim Guidance Report No. DOT HS 811 574 at www.nhtsa.gov/Vehicle+Safety/Electric+Vehicle+Safety+Symposium 481 See NHTSA “Interim Guidance for Electric an d Hybrid Vehicles Equipped with High Voltage Batteries” and o postings at www.nhtsa.gov/About+NHTSA/Press+Releases/NHTSA+Statement+on+C onclusion+of+Chevy+Volt+Investigatio n 482 See NHTSA EVS workshop summary and presentations posted at www.nhtsa.gov/About+NHTSA/Press+Rel eases/NHTSA+Hosts+Technical+Workshop+on+Electric+Vehicle+Safet y114 post - crash s tranded energy in the high power hybrid and/or electric MD / HD V LIBs may pose hazards of electrocution and shock to maintenance technicians and/or emergency responders after a crash or fire incident . The proba bility of high voltage battery - related electrica l shorts, electrocution and fire hazards can be reduced through compliance with FMVSS 305 (which currently applies only to vehicles lighter that 10,000 lbs GVW, and de a ls with electrolyte leakage and loss of electric isolation due to specific crash scenari os mandated by FMVSS 301) , and adherence to the NHTSA interim Safety Guidance . 483 NHTSA is continuing to conduct research on failure scenarios and safety of RESS and LIB s . Such potential hazards may be preventable or mitigated through redundant engineering design, packaging, and abuse testing of batteries and the RESS subsystem . Effective prevention includes the use of a LIB battery management system (BMS) and thermal management system (TMS) , which monitor the voltage and temperature of power electronics , a nd which are programmed to detect faults and shutdown . In addition, crashworthy packaging prevents penetration and leakage of electrolyte from the battery in a crash. OEMs are observing the voluntary SAE electrical safety and battery testing standards (e. g. , J2929 and Battery Abuse T esting H andbook) 484 as generally recommended best safety practice for emerging MD/HDV designers , manufacturers, owners and operators. There are numerous other SAE existing or under development voluntary industry standards and re commended practices for h eavy - d uty vehicle electrification safety 485 (e.g., SAE J2910, J1654, J1673, J1742, J1797, J2344, J2464, J2758, J 2936, J2990 . )

483 Same as 470, and see postings at www.nhtsa.gov/About+NHTSA/Press+Rel eases/NHTSA+Statement+on+Conclusion+of+Chevy+Volt+Investigatio n 484 See http://standards.sae.org/j2929_201102/ for “Electric and Hybrid Vehicle Propulsion Battery System Safety Standard - Lithi um - based Rechargeable Cells” J2929, 2011 - 02 - 18 See J2929,2011 - 02 - 18 “Electric and Hybrid Vehicle Propulsion Battery System Safety Standard - Lithium - based Rechargeable Cells” at http://standards.sae.o rg/j2929_201102/ 485 See www.sae.org/standardsdev/vehicleelectrification.htm and http://ev.sae.org/standards/power - propulsion/items/115 5 REGULATORY BARRIERS ANALYSIS 5.1 Introduction A review of the existing DOT multi - modal (NHTSA, FHWA, and FM CSA) regulatory framework was conducted to evaluate the potential impacts of state, Federal, and NAFTA regulations on the adoption of fuel efficiency - improving technologies and alternative fuels on commercial MD/HD Vs . The focus was on identifying any regul atory barriers to rapid deployment of FE technologies and alternative fuels in the MD/HDV fleet, and a comprehensive list of regulations affecting FE adoption is summarized in Table 5 - 1 . This regulatory review and analysis included a review only of technol ogies with identified relevant regulatory (both Federal and state) barriers : • Impacts on effective HD vehicle size and weight, cargo volume capacity, number of vehicles on road, infrastructure wear and tear; • Aerodynamic technologies that may exceed applicab le trailer length regulations; 486 • Longer combination vehicles that may exceed applicable vehicle length regulations; • Implications of Federal and State inch - width pavement weight laws for using wide based tires on non - tandem axle combination trucks; 487 • National electric and natural gas transmission code standards, if applicable; 488 • Potential conflicts with applicable safety equipment regulations raised by replacing side mirrors with cameras. 489 The NACFE report on “Barriers to the Increased Adoption of Fuel Efficien cy Technologies in the North American On - Road Freight Sector ” 490 focused pr imarily on market barriers, reporting only a few comments on incentives and barriers associated with existing and emerging regulations, such as the NHTSA and EPA fuel efficiency and GHG rule and the CARB tractor trailer GHG Rule. Similarly, the CalHEAT report 491 on market barriers to truck industry adoption of FE technologies and alt - fuels mentioned in Sec.1 did not address remaining regulatory barriers.

486 Transport Canada. 2009a. Aerodynamic Trailer Skirts www.tc.gc .ca/eng/programs/environment - ecofreight - road aerodynamic - trailer - skirts - 2540.htm 487 EPA. 2012. Low Rolling Resistance Tires A Glance at Clea n Freight Strategies www.epa.gov/smartway/documents/partnership/trucks/partnership/techsheets - truck/EPA - 420 - F10 - 041.pdf 488 NREL. 2010a. Electric Vehicle and Infrastructure Codes and Standards Citations www.afdc.energy.gov/pdfs/48605.pdf , NREL. 2010b. Natural Gas Vehicle and Infrastructure Codes and Standards Citations www.afdc.energy.gov/pdfs/486 11.pdf 489 Florida Department of Transportation. 2010. Evaluation of Camera - Based Systems to Reduce Transit Bus Side Collis ions www.nctr.usf.edu/pdf/77905.pdf , Wierwille, W. W., Schaudt, W. A., Blanco, M., Alden, A. S., & Hanowski, R. J. 2011. Enhanced Camera/Video Imaging Systems (E - C/VISs) For Heavy Vehicles: Final Report www.nhtsa.gov/DOT/NHTSA/NVS/Crash%20Avoidance/Technical%20Publications/2011/811483.pdf 490 See NACFE - ICCT 2013 report at www.theicct.org/sites/default/files/publications/ICCT - NACFE CSS_Barriers_Report_Final_20130722.pdf 491 See CalHEAT “Market Barriers And Opportunities For Alte rnative Fuel - Hybrid Systems” June 2013 at www.calstart.org/Libraries/CalHEAT_2013_ Documents_Presentations/CalHEAT_Market_Barriers_and_Opportunit ies_for_Alternative_Fuel - Hybrid_Systems.sflb.ashx116 The DOE/AFDC Fuels and Vehicles posts resources on Federal and State laws and regulations that incentiv ize the vehicle hybridization and electrification 492 and alt - fuels adoption legal incentives by state , 493 but an analysis of regulatory barriers is essential for their removal. The 2002 FMC SA NAFTA rules that apply to Mexico and Canada trucks and buses arriving at border crossings and operating in the United States 494 are enforcing safety regulations that apply to the U.S. truck fleet, but they address neither FE technologies nor alternative f uels . A recent Congressional Research Service (CRS) review of Federal freight policy and legislative initiatives 495 mentions that the Moving Ahead for Progress in the 21 st Century (MAP - 21) legislation instructed DOT to perform a study of existing truck size and weight (TS&W) limits. 496 The goal is to update Federal TS&W regulations applicable to the National Network of highways and arterial access roads (23 CFR 658) and to harmonize the current patchwork of State regulations discussed below and listed in Table 5 - 1 . Federal TS&W limits apply only to the 209,000 miles of interstate highways and principal access arterials, whereas States regulate and restrict LCVs operations on all other highways and roads . Below in Section s 5 .2 - 5 .9, are discussed potential regul atory barriers to the adoption of specific FE technologies . OMB Circular A - 119 requires Federal agencies to adopt and adapt applicable voluntary consensus standards, where applicable, as a cost - effective alternative to rulemaking. 497 The Society of Automoti ve Engineers (SAE), American National Standards Institute (ANSI), NFPA and other standards - developing organization s (SDOs) develop the safety standards and recommended practices for existing and emerging FE technologies and alternative fueled vehicles that are voluntarily adopted by OEMs and veh icle fleet owners and operators . These voluntary industry standards and guidelines may provide sufficient assurance of safe operability of MD/HDVs equipped with FE technologies and using alternative fuels , without re quiring additional regulatory development . 5.2 Adoption of Alternative Clean Fuels There are no major regulatory barriers for the adoption of CNG, LNG, or biodiesel as fuels in MD/HDV fleets. Indeed, there are more Federal and State regulatory and economic/tax incentives for adopting cleaner alternative fuels than barriers to adoption. The DOE Alternative Fuels Data Center has compiled summaries of Federal and State laws and incentives by type of fuel and/or technology. 498 The EPA’s Renewable Fuel Standards and State regulations and tax incentives for technology or fuel adoption to improve air quality (e.g., idle reduction equipment) are compiled and posted by the Transportation Environmental Resource Center. 499
492 See www.afdc.energy.gov/fuels/laws/ELEC/US 493 See www.afdc.energy.gov/laws and database on State incentives at www.dsireusa.org/ 494 FMCSA. 2007b. NAFTA Demonstration Project www.fmcsa.dot.gov/int l - programs/nafta - rules/new - mexrule.htm 495 Frittelli, J. 2012. Federal Freight Policy: An Overview www.fas.org/sgp/crs/misc//R42764.pdf 496 FHWA. 2012b. Moving Ahead for Progress in the 21st Century Act (MAP - 21) www.fhwa.dot.gov/map21/summaryinfo.cfm 497 Composites World. 2007. New hybrid electric bus takes advantage of composites www.compositesworld.com/articles/new - hybrid - electric - bus - takes - advantage - of - composites 498 DOE Alternative Fuels Data Center. 2013a. Laws and Incentives www.afdc.energy.gov/laws/search 499 Tranportation Environmental Resource Center. 2013. Tranportation Environmental Resource Center List of State Regulations and Incentives for Alternative Fuels www.tercenter.org/pages/altfuelM A.htm117 5.3 Hybridization and Electrification 5.3.1 Electric Drivetrain Minimum speed limits may pose a challenge for all - electric technologies as MDHD vehicles equipped with electric drive systems may under some circumstances be unable to travel fast enough to meet minimum speed limits on high grade inclines , per SME input i n Section 3.2.2 . There are no Federal regulations establishing minimum speed limits, so each State regulates this independently. 500 E - truck routes have been voluntarily “certified” by fleet managers for safe operation. 5.3.2 Hybrid H ydraulic Drivetrain Excess wei ght added by hybrid hydraulic drivetrain s may cause MD/HD Vs to exceed applicable weight regulations . National weight standards apply to all commercial vehicle operations on the Interstate Highway System . The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) froze the maximum weight of vehicles on the Interstate System at 20,000 pounds per single axle, 34,000 pounds per tandem axle, and 80,000 pounds overall gross weight, or at the gross weight limit actually and lawfully in effect for such ve hicles in a State on June 1, 1991 (in cases where that limit exceeds 80,000 pounds) . Lower weight limits may be enforced where derived by a bridge formula . States are not allowed to set weight limits on the i nterstate highway s ystem at less than the Federa l weight limits. 501 Beyond the Interstate System, States have the flexibility to set their own weight limits, but Colorado is the only State to provide a weight exemption (of 1,000 pounds) for hybrid vehicles off the Interstate system, as described in the Co lorado Revised Statutes 25 - 7 - 106.8 and 42 - 4 - 508. 5.4 ITS and T elematics There are no major regulatory barriers identified for the adoption of ITS or telematics for MD/HDVs, as seen in Table 5 - 1 . As discussed in Section s 2.4 and 3.2.3, the re are both potential energy savings and efficiency benefits to their fleet - wide adoption. There may be barriers to adoption of telematics technologies by fleet owners and operators related to concerns with system and operational costs, or with drivers ’ privacy protection 502 , when fleet managers monitor the safety and efficiency performance of both assets and drivers that us e GPS and ITS enabled devices . For instance, the FMCSA 2010 and 2011 NPRM related to Electronic On Board Recorders (EOBR) requiremen ts for CMV operators and carriers faced litigation and was withdrawn and later modified in an MPRM requiring Electronic Logging Devices (ELD) and

500 Insurance Institute for Highway Safety. 2013. State Speed Limits www.iihs.org/laws/speedlimits.aspx 501 Vaidya, U. 2012. GATE Center of Excellence at UAB for Lightweight Materials and Manufacturing for Automotive Techn ologies www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration/ti026_vaidya_2012_p.pdf 502 See www.worktruckonline.com/channel/safety - accident - management/article/story/2009/0 8/beware - the - legal pitfalls - in - telematics - monitoring - of - employee - drivers.aspx11 8 Hours of Service (HOS) documentation to address concerns with potential drivers’ privacy and harassment issues . 503 5.5 Human Factors and O perations 5.5.1 Idle R eduction Adoption of idle reduction technologies by MD/HDVs 504 is driven by compliance requirements with EPA Clean Air regulations , as well as with State and local mandates . There are many anti idling technology options verified by the EPA SmartWay program , 505 which applies to certification of new engines, rather than the whole vehicle . Excess weight from idle reduction technologies may cause MD/HDVs to exceed applicable weight regulations (for more det ail on weight regulat ions, see S ection 6.3.2). States may (but are not required to) allow MD/HDVs equipped with idle reduction technology to exceed the maximum gross vehicle weight limit and the axle weight limit by up to 550 pounds to compensate for the additional weight of t he idle reduction technology. 506 Most States have opted to allow weight exemptions for idle reduction technology. However, California, Hawaii, Kentucky, North Carolina, Rhode Island, and Tennessee and the District of Columbia do not allow weight exemptions . Most States and many cities limit the amount of time that MD/HDVs can idle, although the regulations in Table 6 - 1 do not address a specific anti idling technology . 5.5.2 Speed limiters There were no identified regulatory barriers preventing adoption of speed l imiters for MD/HDVs. NHTSA published a notice in the Federal Register on Januar y 3, 2011, granting petitions for rulemaking for an Engine Control Module Speed Limiter Device . 507 5.6 Longer Combination Ve hicles and Truck Size and Weight Limits Existing vehicle l ength and weight regulations may be limiting the adoption of LCVs. Regulatory restrictions for LCVs vary on a State - by - State basis, and this heterogene ity is preserved by Federal law . I n 1991 ISTEA froze maximum weight and length limits for each State at t heir 1991 values. 508 The Federal Highway Administration Office of Freight Management issued in December 2012 a notice soliciting bids for a new study on specific areas of Federal TS&W limits, their operation and their impacts, responding to a mandate in the MAP - 503 See www.fmcsa.dot.gov/regulations/rulemaking/2011 - 8789 and www.fmcsa.dot.gov/regulations/rulemaking/2014 - 11244 504 See www.afdc.energy.gov/conserve/idle_reduction_heavy.html 505 See www.epa.gov/smartway/forpartners/technology.htm#tabs - 4 506 Ibid. 507 NHTSA. 2011a. Federal Motor Vehicle Safety Standard; Engine Control Module Speed Limiter Device https://www.federalregister.gov/articles/2011/01/03/2010 - 33057/federal - motor - vehicle - safety - standard - engine control - module - speed - limiter - device , Transport Canada. 2009a. Aerodynamic Trailer Skirts www.tc.gc.ca/eng/programs/environment - ecofreight - road - aerodynamic - trailer - skirts - 2540.htm 508 Frittelli, J. 2012. Federal Freight Policy: An Overview www.fas.org/sgp/crs/misc//R42764.pdf119 21 legislation. 509 This requirement to further study the issue and complete the study by November 2014 was an outcome of contested proposals to allow six - axle truck/trailer configurations to gross 97,000 pounds. As mentioned, ISTEA enforced a freeze lim iting the use of the longer, heavier double - and triple - trailer combinations to those States in which they were already operating in 1991. 510 Specifically, ISTEA imposed freezes on: 1) the maximum weight of LCVs, which consist of any combination of a truck tractor and two or more trailers or semitrailers which operate on the Interstate System at a gross weight over 80,000 pounds; and (2) the overall length of the cargo carrying units of combination vehicles with two or more such units where one or both excee d 28.5 feet in length on the National Network . The maximum weight of LCVs and the maximum length of the cargo carrying units of combination vehicles is the weight or length in actual and legal operation in a State on June 1, 1991. 511 Weight limits governin g trucking operations across the two international U.S. borders are very different. In crossing to Canada, all but one crossing for NHS highways have a GVW limit of more than 99,000 pounds; 9 of the 11 Interstate crossings have GVW limits of more than 105, 000 pounds. In crossing to Mexico, all four Interstate crossings are limited to a GVW of 80,000 pounds, and six of nine other crossings on the NHS have a GVW of 84,000 pounds (with a permit from Texas). 512 Harmonized operational restrictions, including route designations for LCVs, would help to foster their adoption . Figure 5 - 1 shows the current regulatory environment for LCVs in the United States. The existing environment for LCV operation is a State - by - State patchwork . Recent legi slative initiatives include the 2011 two competing bills in Congress addressing TS&W limits, neither of which became law: 513 • The Safe and Efficient Transportation Act (HR763, S747) to allow States to increase the weight limit from 80,000 lbs. to 97,000 with an extra axle and extra wheels, when appropriate. • The Safe Highways and Infrastructure Protection Act (HR1574, S876) to prohibit any weight limit increase and would extend Federal size and weight limits to the entire National Highway System . • In February 2013 the Safe and Efficient Transportation Act bill was introduced in the House (H.R. 612) to allow States to increase Interstate truck weights to 97,000 pounds, and require LCV tractor - trailers have a sixth axle to decrease per - tire weight and improve br aking.
509 FHWA. 2012a. MAP - 21 Freight Provisi ons www.fhwa.dot.gov/planning/freight_planning/talking_freight/nov282012transcript.cfm 510 FHWA. 2000. Comprehensive Truck Size and Wei ght Study Volume 2, Chapter 3 www.fhwa.dot.gov/reports/tswstudy/Vol2 - Chapter3.pdf 511 Vaidya, U. 2012. GATE Center of Excellence at UAB for Lightweight Materials and Manufacturing for Automotive Technologies www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration/ti026_vaidya_2012_p.pdf 512 FHWA. 2000. Comprehensive Truck Size and Weight Study Volume 2, Chapter 3 www.fhwa.dot.gov/reports/tswstudy/Vol2 - Chapter3.pdf 513 Frittelli, J. 2012. Federal Freight Policy: An Overview www.fas.org/sgp/crs/misc//R42764.pdf120 • In May 2013 the Safe Highways and Infrastructure Preservation Act of 2013 ( SHIPA , H.R. 1906 and S. 880 ) legislation 514 was introduced in Congress, that would extend the current limit of 80,000 pounds on five axles in 53 - foot trailers to the entire 220 ,000 - mile National Highway System, beyond the current 44,0 00 miles of interstates. SHIPA is intended to close a loophole used by States to allow longer, heavier trucks on certain Federal ly funded roadways. Both competing bills are still pending.

Figure 5 - 1 : Regulatory Environment for Longer Combination Vehicles in the United States 5.7 Tire T echnologies 5.7.1 Tire Pressure Management Systems and Automatic Tire Inflation Systems There are no major regulatory barriers for the adoption of TPMS or ATIS for MD / HDVs. The NHTSA regulations in 49 CFR Parts 571.138 and 585 (FMVSS 138) require TPMS for new vehicles under 10,000 pounds (LDVs) and stipulate that the system must include a warning

514 See www.truckingalliance.org/news/lautenberg - introduces - bill - to - restrict - truck - size - and - weight121 signal to the operator when the pr essure is outside a certain pressure range . MD / HDVs are not covered by the NHTSA regulations. 5.7.2 Single Wide Tires Single wide tires meet the inch - width weight requirement s for all States for dual axles but are restricted in certain States to 17,500 lbs. on a single axle at 500 lbs. /inch width limit . They are disallowed on single axle positions on certain double and triple combination vehicles. 515 The ATA has a spreadsheet available of the latest regulations for some States that limit “single tire” use and is w orking with these States to clarify regulations and resolve the limitations. 516 5.7.3 Low Rolling Resista nce T ires By statute, NHTSA’s Tire Fuel Efficiency Consumer Information Program (TFECIP) only rates the fuel efficiency (i.e., rolling resistance), safety (i. e., wet traction), and durability (i.e., tread wear life) of passenger car replacement tires . Some have claimed 517 that low rolling resistance tires may increase stopping distances , and would therefore conflict with corresponding NHTSA tire safety standards (FMVSS 119) 518 re quirement s , which apply to single wide tires . Lab and road testing on LRR performance on packed snow traction concluded that “ the current generation of SmartWay verified LRR tires can offer a similar level of snow traction performance as non - SmartWay verified tires, while reducing fuel consumption and emissions.” As mentioned in section 2.7.3, a NHTSA 2009 study of low and standard rolling resistance tires for light - duty vehicles demonstrated a strong and significant correlation between lower rolling resistance and increased wet slide, or the propensity to lose traction on wet road surfaces . However, this was most significant for vehicles without Anti - lock Braking Systems ( ABS ) . F or newer vehicles with ABS or electronic stability control (ESC) systems, the tradeoff was found to be less significant. 519 The study did not address MD / HDVs, and prior findings may therefore have limited applicability. ABS has been required by NHTSA on all trucks and buses since 1997 - 1999 per FMVSS 121, which would su ggest that it is unlikely that low rolling resistance tires would conflict with the maximum stopping distance for MD / HD V vehicles specified within that regulation. However, the 2009 study did not examine MD / HDVs and the effects on stopping distance may var y based
515 New Generation of Wide - Base Tires: Impact on Trucking Operations, Environment, and Pavements, 2008, TRB at http://trid.trb.org/view.aspx?id=802211 516 Goodyear Truck Tires. 2013. Standards & Regulations www.goodyeartrucktires.com/pdf/resources/service
manual/Retread_S13_V.pdf 517 Cited in Transport Canada Nov. 2012 study “Test Report Packed Snow Performance of Low Rolling Resistance Class 8 Heavy Truck Tires” at www.tc.gc.ca/media/documents/programs/n rc_test_report packed_snow_performance_eng.pdf 518 See FMVSS 119, New Pneumatic Tires for Vehicles Other Than Passenger Cars, www.nhtsa.gov/cars/rules/import/FMVSS/#SN119 519 Evans, L. R., MacIsaac, J. D., Harris, J. R., Yates, K., Dudek, W., Holmes, J., Popio, J., Rice, D., & Salaani, M. K. 2009. NHTSA Tire Fuel Efficiency Consumer Information Program Development: Phase 2

– Effects of Tire Rolling Resistance Levels on Traction, Treadwear, and Vehicle Fuel Economy www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle%20Research%20&%20Test%20Center%20%28VRTC%29/ca/Tires/81115 4.pdf122 on vehicle size and weight . Existing truck stopping distance requirements (49 CFR 571.121) , as well as proposed ESC 520 standards and a grant of petition for rulemaking on speed limiter s 521 could create effective countermeasures for the potential degrad ation of braking or vehicle handling performance. 5.8 Aerodynamic C omponents Aerodynamic technologies may conflict with applicable length and width regulations . However, according to FHWA regulations in 23 CFR Part 658.16 and A ppendix D (see Table 5 - 1 ), aerodynamic devices that do not extend more than 5 feet beyond the rear of the vehicle are exempt from length limits, provided they do not have the strength, rigidity, or mass to damage a vehicle or injure a passenger and do not obscure tail lamps, turn signals, marker lamps, identification lamps, or any other required safety devices. 522 Replacing side mirrors with cameras may conflict with applicable safety equipment regulations . NHTSA regulations in 49 CFR 571.111 require mirrors and do not include wording to allow cameras as an alternative . According to this regulation each multipurpose passenger vehicle, bus, or truck with a GVWR of more than 4,536 kilograms shall: “Have outside mirrors of unit magnification, each with not less than 323 square centimeters of reflective surface, installed with stable supports on both sides of the vehicle. The mirrors shall be located so as to provide the driver a view to the rear along both sides of the vehicle and shall be adjustable both in the horizont al and vertical directions to view the rearward scene.” 5.9 Lightweight C omponents The NHTSA FMVSS 121, Air Brake Systems 523 regulation mandates 250 - 310 foot maximum stopping distances for heavy trucks at 60 mph. To provide more stopping power and counteract fad e at high temperatures, brake manufacturers have increased the size and weight of their drum systems . However, one of several options for vehicle weight reduction is for brake systems to become smaller and lighter , aid ing manufacturers in meeting fuel effi ciency standards . Reducing weight and handl ing more work in order to meet required stopping distances are the dual forces driving the adoption of air - disc brakes . This does not create an actual adoption barrie r but it is possible that future, more stringen t fuel efficiency regulations could lead to potential conflict between these two purposes.

520 https://www.Federalregister.gov/articles/2012/05/23/2012 - 12212/Federal - motor - vehicle - safety - standards electronic - stability - control - systems - for - heavy - vehicl es 521 https://www.Federalregister.gov/articles/2011/01/03/2010 - 33057/Federal - motor - vehicle - safet y - standard - engine control - module - speed - limiter - device . 522 Vaidya, U. 2012. GATE Center of Excellence at UAB for Lightweight Materials and Manufacturing for Automotive Technologies www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration/ti026_vaidya_2012_p.pdf www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration/ti026_vaidya_2012_p.pdf 523 www.nhtsa.gov/DOT/NHTS A/Rulemaking/Rules/Associated%20Files/121_Stopping_Distance_FR.pdf123 5.10 Findings and Conclusions Regarding Regulatory Barriers There are few regulatory barriers to the adoption of FE technologies for MD / HDVs. Tab le 5 - 1 lists various categories of FE technologies and discusses the potential regulatory barriers that were investigated in this report . In ea ch row a green “no” indicates that there are no documented regulatory barriers and a red “yes” indicates that th ere may be a barrier or conflict. Most of the potential barriers relate in some way to truck size and weight (TS&W) regulations . This may have implications for hybrid - electric and hybrid - hydraulic technologies, battery electric vehicles, idle reduction te chnologies, and LCVs . Size and weight regul ations vary from State to State and the restrictions of one State may have indirect consequences on the use of FE technologies in surrounding States since truck operators must be compliant with regulations at ever y stage along a given route . In the case of LCVs, the Intermodal Surface Transportation Efficiency Act (ISTEA) preserved the heterogeneity of State regulations by enforcing a freeze limiting the use of the longer, heavier double - and triple - trailer combina tions to those States in which they were already operating in 1991 (see S ection 5 .6). 524 However, in December 2012 t he FHWA Office of Freight Management issued a notice soliciting bids for a new study on specific areas of Federal TS&W limits, their operati on and their impact s, in response to a mandate in the MAP - 21 legislation. 525 Th is requirement for further study was an outcome of contested proposals to allow six - axle truck/trailer configurations to gross 97,000 pounds . After further study FHWA may update the regulations on LCVs . A regulatory barrier for future consideration relates to t he additional weight of some future (Phase 2) MD / HD V technologies. The need for their proximity to the engine (e.g., waste heat recovery, turbo compounding) may bump tractor weights up above the 12,000 lb. front axle weight limit. This challenge was suggested in some DOE sponsored SuperTruck projects . 526 Another potential regulatory barrier relates to certain restrictions on the use of single wide tires . T hese limitations simil arly vary from State to state . O rganizations such as the ATA are working to resolve inconsistencies and to promote harmonized regulations across State boundaries for single wid e tires . Also, as described in S ection 5 .8, replacing side mirrors with cameras may conflict with applicable safety equipment regulations . T he NHTSA regulations in 49 CFR 571.111 appear to require mirrors and do not include language to allow cameras as an alternative. There are a few areas where pending or proposed regulatory action may influence the adoption of FE technologies . For instance, NHTSA has begun a rulemaking process to consider speed limiting devices on heavy - duty trucks, a s described in S ection 2.5.1.3 . In addition, FMCSA will

524 FHWA. 2000. Comprehensive Truck Size and Weight Study Volume 2, Chapter 3 www.fhwa.dot.gov/repo rts/tswstudy/Vol2 - Chapter3.pdf 525 FHWA. 2012a. MAP - 21 Freight Provisions www.fhwa.dot.gov/planning/freight_planning/talking_freight/nov282012t ranscript.cfm 526 See Navistar project weight per axle at www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/veh_sys_sim/vss06 4_jadin_2012_o.pdf124 consider updated regulations regarding inspe ctions of NGVs 527 and has conducted research to identify relevant safety issues raised by stakeholders. 528 Finally, OMB Circular A - 119 requires Federal agencies to adopt and adapt applicable voluntary consensus standards, where applicable, as a cost - effective alternative to rulemaking. 529 Consensus standards by organizations such as SAE, ANSI, NFPA and others may provide sufficient assurance of safe operability of MDHDVs equipped with FE technologies and using alternative fuels.

527 FMCSA. 2012a. Natural Gas Systems, Final Report, Kwan, Q. 2012. Safety Considerations Related to Commercial Vehicles Using Natural Gas www1.eere.energy.gov/cleancities/pdfs/ngvtf12_kwan.pdf 528 Transport Canada. 2009b. Summary Report - Assessment of a Heavy Truck Spee d Limiter Requirement in Canada www.tc.gc.ca/eng/roadsafety/tp - tp14808 - menu - 370.htm 529 Composites World. 2007. New hybrid electric bus takes advantage of composites www.compositesworld.com/articles/new - hybrid - electric - bus - takes - advantage - of - composites , Office of Management and Budget. 1998. Circular No. A - 119 Revised www.whitehouse.gov/omb/circulars_a119125 Table 5 - 1 : Summary of Potential Regulatory Barriers for the Adoption of MD/HDV Fuel Efficiency Technologies Chapter index FE technology Potential issue/conflict with existing regulations Regulatory Entity Regulation’s full name Potential Barrier? Description 2.8.3 Aerodynamic components Aerodynamic technologies may exceed applicable trailer length regulations. FHWA 23 CFR Part 658.16 - Length limit exemptions. (and appendix D to 23 CFR 658) - No Aerodynamic devices that do not extend more than 5 feet beyond the rear of the vehicle are exempt from length limits, provided they do not have the strength, rigidity, or mass to damage a vehicle or injure a passenger and do not obscure tail lamps, turn signals, marker lamps, identification lamps, or any other requir ed safety devices. 3.2.8 Aerodynamic components Replacing side mirrors with cameras may conflict with applicable safety equipment regulations FHWA 23 CFR Part 658.16 (and appendix D to 23 CFR 658) No FHWA: Certain devices are allowed to extend beyond the width limit, including rear - view mirrors, so switching to cameras will not alter the effective width limit. 3.2.8 Aerodynamic components Replacing side mirrors with cameras may conflict with applicable safety equipment regulations NHTSA 49 CFR 571.111 Ye s NHTSA: Regulation 571 appears to require mirrors and does not include wording to allow cameras as an alternative. 2.2.2.3 Biodiesel None No 2.2.1.3, 5.2.1.1 CNG None No 3.2.2 Hybrid/electric MDHD vehicles may not be able to travel fast enough to meet minimum speed limits on high grade inclines. State No There are no Federal regulations establishing minimum speed limits. Each State regulates this independently . E - truck routes have been voluntarily “certified” by fleet managers for safe operati on. 3.2.2 Hybrid/hydraulic Excess weight added by a series HH drivetrain may exceed applicable vehicle weight regulations. FHWA 23 CFR 658.17, 23 CFR 658.23 Yes National weight standards apply to all commercial vehicle operations on the Interstate Highway System. ISTEA froze the weights of truck tractors with two or more trailing units operating above 80,000 pounds on the Interstate System at the weight limits actually and lawfully in effect for such vehicles in a State on June 1, 1991. FHWA issued a final rule on June 13, 1994. 3.2.2 Hybrid/hydraulic Excess weight added by a series HH drivetrain may exceed applicable vehicle weight regulations. State Colorado Revised Statutes 25 - 7 - 106.8 and 42 - 4 - 508 Yes Only one state, Colorado, provides a 1,000 lb. vehi cle weight exemption for hybrid vehicles off the Interstate system. 2.5.2.3, 3.2.5 Idle reduction technologies Excess weight from idle reduction technology may exceed applicable vehicle weight regulations. FHWA Federal: Public Law 112 - 141 (MAP - 21) and 23 U.S. Code 127(a)(12) No Idle Reduction Technology Weight Exemption: States may (but are not required to) allow heavy - duty vehicles equipped with idle reduction technology to exceed the maximum gross vehicle weight limit and the axle weight limit by up to 5 50 pounds (lbs.) to compensate for the additional weight of the idle reduction technology .126 Chapter index FE technology Potential issue/conflict with existing regulations Regulatory Entity Regulation’s full name Potential Barrier? Description 2.5.2.3, 3.2.5 Idle reduction technologies Extra weight from incorporation of idle reduction technology may exceed applicable vehicle weight regulations. State Ye s Most States allow heavy - duty vehicles equipped with idle reduction technology to exceed the maximum gross vehicle weight limit and the axle weight limit by up to 550 pounds (lbs.) to compensate for the additional weight of the idle reduction technology . However, six States (California, Hawaii, Kentucky, North Carolina, Rhode Island, Tennessee) and the District of Columbia do not allow weight exemptions. Most States and many cities limit the amount of time that MD/HDVs can idle, although 49 - State and local regulations do not specifically address anti - idling technology . 2.4.1.3 ITS/telematics None No 3.2.9, 4 .2.3 Lightweighting materials Stopping distance regulations could conflict with the desire to decrease weight NHTSA FMVSS 121: Air Brake Systems 4 9 CFR Part 571 Yes NHTSA FMVSS 121 mandates 250 - 310 foot maximum stopping distances for heavy trucks at 60 mph. To provide more stopping power and counteract fade at high temperatures, brake makers have increased the size and weight of their drum systems . However, these design changes may decrease fuel efficiency instead of aiding OEMs in meeting the new GHG - FE rules. There is now greater demand for brake systems that are smaller and lighter yet still handle more work; this is driving the adoption of air - d isc brakes. 2.2.1.4 LNG None No 2.6.3 Longer combination vehicles Longer combination vehicles may exceed applicable vehicle length regulations. FHWA 23 CFR 658.9, 23 CFR 658.11, and Appendix A to 23 CFR Part 658 Yes ISTEA imposed freezes on: 1) on the maximum weight of LCVs, which consist of any combination of a truck tractor and two or more trailers or semitrailers which operate on the Interstate System at a gross weight over 80,000 pounds; and (2) on the overall length of the cargo carrying units of combination vehicles with two or more such units where one or both exceed 28.5 feet in length on the National Network . The maximum weight of LCVs and the maximum length of the cargo carrying units of combination vehicles is the weight or length in actual a nd legal operation in a State on June 1, 1991 . Therefore, except for within the grandfathered States , LCVs cannot operate on Interstate highways . There is a patchwork of national (FHWA), international (Canamex), and State - based LCV restrictions . Harmoniz ed operational restrictions, including route designations for LCVs, should be considered . 2.6.3 Longer combination vehicles Longer combination vehicles may exceed applicable vehicle length regulations. State Yes Some States do not allow LCVs (See map in cluded in chapter 6 text).127 Chapter index FE technology Potential issue/conflict with existing regulations Regulatory Entity Regulation’s full name Potential Barrier? Description 2.6.3, 4 .2.5 Longer combination vehicles Longer combination vehicles may exceed applicable vehicle weight regulations. FHWA 23 CFR 658.23 LCV freeze (ISTEA freeze), including Appendix C (grandfathered state - wise LCV limits) Yes ISTEA imposed freezes on: 1) on the maximum weight of LCVs, which consist of any combination of a truck tractor and two or more trailers or semitrailers which operate on the Interstate System at a gross weight over 80,000 pounds; and (2) on the overall len gth of the cargo carrying units of combination vehicles with two or more such units where one or both exceed 28.5 feet in length on the National Network . The maximum weight of LCVs and the maximum length of the cargo carrying units of combination vehicles is the weight or length in actual and legal operation in a State on June 1, 1991 . 2.7.3.3, 4 .2.4, 3.2.7 Low rolling resistance tires Low rolling resistance tires may conflict with stopping distance regulations. NHTSA 49 CFR Part 575 FMVSS 121

- Air Brake Systems - Trucks, Buses, and Trailers No ABS has been required by NHTSA on all trucks and buses since 1997 - 1999 per FMVSS 121 . The average age of Class 8 tractors, which stand to benefit the most from LRR tires, is approximately 9 years. FMVSS 121 also s pecifies maximum stopping distance for air brake systems on MDHDVs, regardless of tires . Potential countermeasures to degradation of braking or vehicle handling performance include electronic stability control and speed limiter implementation. 2.7.3.3, 5. 2.4, 3.2.7 Low rolling resistance tires Low rolling resistance tires may conflict with stopping distance regulations. FMCSA 49 CFR 393.52(a)(3) FMCSA brake performance. No FMCSA regulates the maximum braking distance at 20 mph for GVW greater than 10,000 l bs . Potential countermeasures to degradation of braking or vehicle handling performance include electronic stability control and speed limiter implementation . 2.7.2.3 Single - wide tires Inch - width pavement weight laws may preclude the use of wide based ti res on non - tandem axle combination trucks. FHWA No National weight standards apply to commercial vehicle operations on the Interstate Highway System, an approximately 40,000 - mile system of limited access, divided highways that spans the Nation . Off the I nterstate Highway System, States may set their own commercial vehicle weight standards. 2.7.2.3 Single wide tires State inch - width pavement weight laws may preclude the use of wide based tires on non - tandem axle combination trucks. State Yes Single wide tires meet the inch width - weight limits for all States , but are restricted in certain States to 17,500 lbs. on a single axle at 500 lbs./inch width limit, and are disallowed on single axle positions on certain double and triple combination vehicles (from a white paper developed by the American Trucking Association) . The American Trucking Association has a spreadsheet available of the latest regulations for some States that limit “single tire” use. Work is ongoing with these States to clarify regulations an d resolve the limitations.128 Chapter index FE technology Potential issue/conflict with existing regulations Regulatory Entity Regulation’s full name Potential Barrier? Description 2.5.1.3, 3.2.4 Speed limiters None No NHTSA plans to publish a notice of proposed rulemaking in late 2013. 530 2.7.1.3 TPMS/ATIS None NHTSA 49 CFR Parts 571.138 and 585: FMVSS 138 Tire Pressure Monitoring Systems No NHTSA: TPMS is required for new vehicles under 10,000 lbs., and it must include a warning signal to the operator when the pressure is outside a certain pressure range . MDHDVs are not covered by the regulation .

530 See “Truck Speed Limiter Proposal Returned to NHTSA,” www.truckinginfo.com/channel/safety compliance/news/story/2013/05/truck - speed - limiter - proposal - returned - to - nhtsa.aspx?prestitial=1129 6 CONCLUSIONS AND RECO MMENDATIONS The r elevant safety findings from the literature review , summariz ed in Chapter 2 , were complemented by inputs from focused interviews with experienced SMEs regarding the rapidly expanding use of alternative fuels , as discussed in Chapter 3. A cross - cutting measure for the saf e deployment of new FE technologies and fuels is to provide improved CMV driver training . S afety concerns identified from the literature review and SMEs’ inputs can be prevented or mitigated by complying with applicable regulations , and safety standards an d industry best practices and can be addressed by evolving ITS technologies and collision prevention devices . The key finding from this study is that there are no major safety hazards preventing the adoption of FE technologies or the increased use of alter native fuels and vehicle electrification by the Nation ’s MD/HDV fleet in order to achieve environmental and economic benefits while comply ing with NHTS/EPA regulations . Chapter 2 safety - relevant fuel - or technology - specific specific findings include: • Both CNG - and LNG - powered vehicles present potential hazards, and call for well known engineering and process controls to assure safe operability and crashworthiness . However, based on the reported incident rates of NGVs and the experiences of adopting fleets, it appears that NGVs can be operated at least as safely as diesel MD/HDVs . Using natural gas instead of diesel fuel may help fleets comply with the MD/HD greenhouse gas rules that require up to 20 percent emissions reduction by 2018 . • There are no safety contraindications to the large scale fleet adoption of CNG or LNG fueled h eavy - d uty trucks and buses, and there is ample experience with the safe operation of large public transit fleets . Voluntary industry standards and best practices suffice for safety a ssurance, though improved training of CMV operators and maintenance staff is needed to ensure natural gas safety of equipment and operating procedures . S ound design , manufacture and inspection of natural gas storage tanks will further reduce the potential for leaks, tank ruptures, fires, and explosions. • Biodiesel blends used as drop - in fuels have presented some operational safety concerns depending on blending fraction, such as material compatibility, bio - fouling sludge accumulation, or cold - weather gelling . However, best practices for biodiesel storage, and improved gaskets and seals that are biodiesel resistant, combined with regular maintenance and leak inspection schedule for the fuel lines and components enable the safe use of biodiesel in newer MD/HDVs . • Propane ( LPG , or autogas ) presents well - known hazards due to overpressure in tank overfill, and unintended ignition (due to leaks or a crash) that are preventable by using Overfill Prevention Devices (OPD) that supplement the automatic stop - fill system o n the fueling station side, and pressure release devices (PRD) . Established best practices and safety codes (e.g. NFPA) have proven that propane fueled MD/HDVs can be as operationally safe as the conventionally - fueled counterparts . • As the market penetrati on of hybrid and electric drivetrain accelerates, and the capacity and reliability of lithium ion batteries used in Rechargeable Energy Storage Systems improve, associated potential safety hazards (e.g., electrocution and stranded energy, thermal runaway l eading to battery fire) have become well understood , preventable and manageable . Existing and emerging industry technical and safety voluntary standards , compliance with applicable NHTSA regulations and guidance , as well as growing130 experience with the oper ation of hybrid and electric MD/HDVs will enable the large scale adoption of safer and more efficient power - train electrification technologies . Key safety findings from the literature review pertaining to the specific FE technologies implemented to date i n the MD/HDV fleet include: • T elematics , integrating on - board ITS sensors, video and audio alerts for MD/HDV drivers, offer potential improvements in both driver safety performance and fuel efficiency . Both camera and non - camera based telematics setups are currently integrated with available crash avoidance systems (such as ESC, RSC, LD WS, etc.) and appear to be well accepted by MD/HDV fleet drivers . • Both experience abroad and the cited U.S. studies of trucks equipped with active speed limiters indicated a safety benefit, as measured by up to 50 percent reduced crash rates, in addition to fuel savings and other benefits, with good CMV driver acceptance. Any negative aspects were small and avoidable if all the speed limitation devices were set to the same spe ed, so there would be less need for overtaking at highway speeds. • No literature reports of adverse safety impacts were found regarding imp lement ation of o n - board idle - reduction technologies in MD/HDVs (such as automatic start - stop, direct fired heaters, an d APUs ). • T here was no clear consensus from the literature regarding the relative crash rates and highway safety impacts of LCV s , due to lack of sufficient data and controls and inconsistent study methodologies . R ecent safety evaluation s of LCVs and ongoing MAP 21 mandated studies will clarify and quantify this issue. • Tire technologies for FE (including ATIS, TPMS, LRR and single - wide tires) literature raised potential safety concerns regarding lower stability or loss of control, e.g., when tires pressure is uneven or a single wide tire blows out on the highway. However, systems such as automated tire monitoring systems and stability enhancing electronic systems (ABS, ESC, RSC) promise to compensate and mitigate any adverse safety impacts. • Aerodynamic techno logies that offer significant fuel savings have raised potential concerns about vehicle damage or injury in case of detached fairings or skirts, although there were no documented incidents of this type in the literature . Conversely, there is a potential sa fety benefit from skirts that also function as side underride guards to protect VRUs in multimodal operating environments . • The increasing use of l ight weight ing materials may pose some safety and crashworthiness hazards , depending on the ir performance in s tructural or other vehicle subsystem applications (chassis, power - train, crash box or safety cage) . Some composite s (fiberglass, plastics, CFRC, foams) may become brittle on impa ct or due to weathering from UV and extreme cold, or consumed by fires. No exa mples of such lightweight material failures on MD/HDVs were identified in the literature. Industry has developed advanced, high performance lightweight material options tailored to their automotive application, e.g., thermoplastics resistant to UV and weat hering. Chapter 3 summarized the safety inputs offered by a representative group of SMEs regarding fleet adoption of FE technologies and alternative fuels. SMEs indicated that there was a learning curve to the process: design and engineer novel subsystem s ; integrate them safely in the vehicle; inspect, maintain and refuel fleet vehicles for safe operability ; and train staff to safely operate a fleet of such new MD/HDVs . Although some SMEs raised specific safety concerns , their131 experience demonstra tes that system - or fuel - specific hazards can be prevent ed or mitigated by observing applicable industry standards, and by training managers, operators and maintenance staff in safety best practices. Specific safety insight s mentioned by the SMEs, based on their experience included: • Alternative fuels did not raise major safety concerns but generally required better education and training of maintenance staff and operators. There was a necdotal safety concern regarding high pressure (4 , 000 psi) CNG cylinders that co uld potentially explod e in a crash scenario or if otherwise ruptured . However, a ging CNG fuel tank safety can be assured by enforcing regulations such as FMVSS 3 04 a nd by periodic tank inspection s, end - of - life disposal and replacement. A propane truck flee t manager found the fuel to be as safe as or safer than gasoline , and reported no safety issues with the company’s propane , nor with hy brid gasoline - electric trucks . • OEMs of d rivetrain hybridization and electrification systems, including batteries for the rechargeable energy storage system indicated that they u ndergo multiple safety tests and are designed with fail - safes for various misuse and abuse scenarios . A potential safety risk wa s the integration of hybrid components downstream by bodybuilders in re trofits, as opposed to new vehicles. Another potential safety concern raised was the uncertain battery lifetime due to variability of climate , operation duty - cycles and aging degradation . Without state - of - charge indicators, vehicles could become underpower ed or s tranded if the battery degrades and is not serviced or replaced in a timely manner . • ITS and telematics raised no safety concerns; on the contrary, fleet manager s stated that “ efficient drivers are safer drivers .” Monitoring and recording of driver behavior, combined with coaching, appeared to reduce distracted and aggressive driving and provided significant FE and safety benefits . • Tire technologies: Wide base tires safety concern s stemmed from the decrease in tire redundancy in case of a tire blowo ut at highway speeds . In the case of LRR, a concern was that these tires could negatively affect truck stopping distance and stability control . • S peed - limiter safety concerns could be encountered when trucks pass other vehicles on the highway instead of sta ying in the right - hand lane behind other vehicles . H owever, by combining speed limiters with driver training programs the truck fleet safety performance could actually improve . • Aerodynamic system s safety to date was satisfactory , with no instances of on - r oad detaching of components . However, covering the underside or other safety - critical components with aerodynamic fairings can make them harder to inspect, (e.g., worn lugs, CNG relief valve shrouds, wheel covers, and certain fairings ) . Drivers and inspect ors need to be able to see through wheel covers and to be able to access lug nuts through them. These covers must also be durable to withstand frequent road abuse . • For lightweighting materials, safety concern s raised w ere potentially lower crashworthiness (debonding , or brittle fracture in impact) , and potential for decreased survivability in vehicle fires depending on the specific composite or other material choice and its application . The scenario - based deterministic hazard analysis presented in Chapter 4 reflected not only literature safety findings and SME’s safety concerns, but also reported truck or bus mishaps that have occurred . Key hazard analysis scenarios inclu ded: CNG - fueled truck and bus vehicle fire or132 e xplosion d ue to CNG t ank r upture, when pressurized fuel tanks degraded due to aging or PRDs failed ; LNG truck crashes leading to fires, or LNG refu e ling - related mishaps; the flammability or brittle fracture issues related to lightweighting materials in crashes; reduced safety performance for ei ther LRR or wide - base tires; highway pile - ups when LCVs attempt to pass at highways speeds; aerodynamic components detaching while the vehicle traveled on a busy highway or urban roadway; and fires resulting to overheated lithium ion batteries in electric or hybrid buses . All these hypothetical worst case scenarios we re shown to be preventable and possible to mitigate by observing safety regulations and voluntary standards, or with engineering and operational best practices.133 7 APPENDICES 7.1 Operations/Human F actors Bibliography Adams, R. 2010. CNG Transit Experience Survey (Clean Vehicle Education Foundation) www1.eere.energy.gov/cleancities/pdfs/n gvtf10_trans_lessons_learned.pdf Adams, T., Kleinmaier, D., Marach, A., Helfrich, G., Levine, J., & Bittner, J. 2012. Longer Combination Vehicles: An Estimation of their Benefits and Public Perception of Their Use www.wistrans.org/cfire/.../CFIRE_05 - 01_Final_Report.pdf American Transportation Research Institute. 2011. Predicting Truck Crash Involvement: A 2011 Update www.atri online.org/research/results/ATRI_Crash_Predictor_One_Pg_Summary_Apr_2011.pdf American Trucking Association. 2009. Expanding ATA’s Safety Agenda Executive Summary www.truckline.com/Newsroom/Policy%20Papers/Safety%20Task%20Force%20Report.p df Andras Varhelyi, T. M. 2000. The effects of in - car speed limiters: field studies http://partnet.vtt.fi/evaserve/evaserve_tool/aineisto/limiter.pdf Argonne National Laboratory. 2011. Idle Reduction Technologies for Heavy - Duty Vehicles www.transportation.anl.gov/engines/heavy_technologies.html Automotive Fleet. 2012. Verizon’s Sustainable Fleet Program Manager to Discuss Routing Technologies www.automotive - fleet.com/Channel/GPS Telematics/News/Story/2012/03/Verizon - s - Sustainable - Fleet - Program - Manager - to Discuss - Routing - Technologies.aspx Barnett , R. 2012. Crash Indicator BASIC: Stay Safe on America’s Busy Highways http://xrscorp.com/blog/industry - news/crash - indicator - basic/ Barnitt, R. 2011. FedEx Express Gasoline Hybrid Electric Delivery Truck Evaluation: 12 - Month Report www.nrel.gov/docs/fy11osti/48896.pdf Barry, K. 2012. Trucks use GPS to anticipate hills, save fuel www.wired.com/autopia/2012/05/trucks - use - gps - to - anticipate - hills - save - fuel/ Beegle, B. 2012. Worksite idle reduction www.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26496 Boesel, J. 2012. Why now is the right time to diversify your portfolio...and help make the nation stronger and better www.ntea.com/WorkArea/linkit.aspx/LinkIdentifier=id%26ItemID=26495&ei=NFXzT4 6ZKsjZ6wHFqNyqCA&usg=AFQjCNFrhMcO367FTlOU.S.am1zicJn3vvyg British Columbia Ministry of Transport ation and Infrastructure. 2011. Long Combination Vehicles Program www.th.gov.bc.ca/cvse/lcv/faqs.htm Calabrese, D. 2012. SAE updates truck standards for wide variety of systems http://trid.trb.org/view.aspx?id=1137935 California Air Resources Board. 2009. Heavy - Duty Vehicle Idling Emission Reduction Program www.arb.ca.gov /msprog/truck - idling/truck - idling.htm California Department of Transportation. 2009. 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Proper brake maintenance is the best defense against brake safety week violations; enforcement agencies will inspect 3 0,000 vehicles w ww.cvsa.org/news/2012_press.php Commercial Vehicle Safety Alliance: Technical Working Committees. 2012 . w ww.cvsa.org/committees/ index.php Conti, G. 2012. Industry stays focused on efficiency as fuel costs rise w ww.truckinginfo.com/news/news - detail.asp?news_id=76651 Craft, R., Skretta, M., & Cotty, S. 20 10. Analysis Brief: The Bus Crash Causation Study (FMCSA) w ww.fmcsa.dot.gov/documents/facts - research/Analysis_Brief - 1.pdf DeCoster, T. 2012. Parker's hydraulic hybrid te chnologies w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26445 DOE EERE. 2006. Fact #411: February 13, 2006 States that Allow Longer Combination Vehicles w ww1.eere.energy.gov/vehiclesandfuels/facts/2006_fcvt_fotw411.html DOE EERE. 2011a. 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Changes to Consider in the Federal Motor Carrier Safety Regulations and North American Standard Inspection Procedures to Accommodate Hydrogen as an Alternative w ww.trb.org/Main/Blurbs/159855.aspx FMCSA. 2012. Research on the Safety Impacts of Speed Limiter Device Installations on Commercial Motor Vehicles: Phase II w ww.fmcsa.dot.gov/facts - research/research technology/report/Speed - Limiters.pdf Fontaine. 150SP Fifth Wheel Instruction Manual w ww.fifthwheel eur ope.com/pdf/instruction/150SP.pdf Friedman, D. M., & Malcosky, N. D. Liquefied Natural Gas Safety in Transit Operations: Final Report http://trid.trb.org/view.aspx?id=713273 Friedman, D. N., & Malcos ky, N. D. 1995. Compressed Natural Gas Safety in Transit Operations: Clean Air Program http://144.171.11.39/view.aspx?id=573745 Gaines, L., Levinson, T., & McConnell, S. 2011. To Idle or Not To Idle: That Is the Question w ww.transportation.anl.gov/pdfs/EE/642.PDF Gehm, R. 2012a. Greater connectivity coming to heavy trucks w ww.sae.org/mag s/tbe/10927/ Gehm, R. 2012b. Putting electrification to work http://ev.sae.org/article/10917/ Gentry, W. 2012. Statement of William Gentry, President, Gentry Trailways and on behalf of American Bus Associat ion and United Motorcoach Association Subcommittee on Highways and Transit, House Transportation and infrastructure Committee, U.S. House of Representatives http://republicans.transportation.house.gov/Media/file/TestimonyHighways/2012 - 09 - 13 - Gentry.pdf Grant, C. 2012. Emergency responder related electric vehicle research w ww.sae.org/events/nevss/summit/2012_EV_Safety_Summit_grant.pdf GreenRoad. 2012 . http://greenroad.com/ Grenzeback, L. R. 2011. Freight Transportation Challenge: More Trucks, More Fuel, More GHGs? http://its.ucdavis.edu/events/outreachevents/asilomar2011/presentations2/session%205/G renzeback_Asilomar2011_Freight_v2.pdf Greszl er, A. 2009. Technologies and Policies for Improving Truck Fuel Efficiency & Reducing CO2 w ww.aceee.org/files/pdf/conferences/30th/transport/Greszler.pdf Greszler, A. 20 11. H eavy - D uty Truck Technologies for Reducing Fuel Consumption and GHG Emissions136 http://its.ucdavis.edu/events/outrea chevents/asilomar2011/presentations2/session%205/G renszler_Asilomar%202011%20Volvo.pdf Hollick, P. 2012. Sustainability: Green fleets, Squaring the environmental circle w ww.bus ex.co m/article/sustainability - green - fleets House Transportation and Infrastructure Committee. 2012a. Duncan holds hearing focused on improving truck and bus safety program http://tr ansportation.house.gov/News/PRArticle.aspx?NewsID=1724 House Transportation and Infrastructure Committee. 2012b. Subcommittee on Highways and Transit Hearing on “Evaluating the Effectiveness of DOT's Truck and Bus Safety Program” http://democrats.transportation.house.gov/hearing/subcommittee - highways and - transit - hearing - %E2%80%9Cevaluating - effective ness - dots - truck - and - bus IIHS. Speed Limiters in Trucks Would Serve 2 Purposes w ww.iihs.org/externaldata/srdata/docs/sr4508.pdf Industrial Technology. Festo picked for groundbreaking f ifthwheel development w ww.industrialtechnology.co.uk/index.php?pageId=47&aid=490 Integrys Trillium CNG. 2012. CNG gaseous fuels: a successful alternative w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26500 Johnston, J. 2007. Comments of the owner - operator independent drivers association, inc in response to notice and request fo r comments Motor Vehicle and Carrier Safety Standards [Docket No. NHTSA - 2007 - 26851] w ww.ooida.com/Issues&Actions/Regulatory/commentd ocs/speed%20limiter%20comme nts%20final%203 - 27 - 07.pdf JOST. 2011. 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IIHS Letter re: Motor Vehicle and Carrier Safety Stan dards; Devices to Limit the Speed of Certain Trucks Request for Comments; Docket No. NHTSA - 2007 - 26851 w ww.iihs.org/laws/comments/pdf/nhtsa_fmcsa_ds_atm_032707.pdf Menzies, J. 2013. The future potential of truck telematics w ww.trucknews.com/news/the - future potential - of - truck - telematics/1002000560 Miller, E. 2013. Speed, Lack of S eat Belts Cited By U.S. in Truck Fatality Spike w ww.ttnews.com/gateclient/logonPC.aspx?storyid=31050&t=Speed - Lack - of - S eat - Belts Cited - By - U.S. - in - Truck - Fatality - Spike Morgenstern, M. 2012. Propane tank explodes in McDonald's drive - through w ww.theblaze.com/stories/propane - tank - explodes - in - mcdonalds - drive - through/137 Mugno, S. 2012. Written Statement of American Trucking Associations, Inc. Before the Committee on Transportation and Infrastructure Subcommittee on Highways and Transit U.S. House of Representatives Hearing "Evaluatin g the effectivenes of DOT's truck and bus safety program" w ww.trucking.org/Newsroom/Testimony1/FINAL%20ATA%20Testimony%20CSA%20 Sept%202012.pdf Natio nal Shippers Strategic Transportation Council. 2012. Competing Bills on Truck Size and Weight Limits http://freightadvocacy.org/key - issues/truck - size - and - weight - limits NGV J ournal. 2011. National NGV Fleet Forum forms in the United States w ww.ngvjournal.com/en/vehicles/item/5048 - national - ngv - fleet - forum - forms - in - the united - states NHTSA. 2008a. National Motor Vehicle Crash Causation Survey: Databook of NMVCCS Variables w ww - nrd.nhtsa.dot.gov/Pubs/811052.pdf NHTSA. 2008b. National Motor Vehicle Crash Causa tion Survey w ww - nrd.nhtsa.dot.gov/Pubs/811059.PDF NHTSA. 2010. Grant of petition for rulemaking: Federal Motor Vehicle Safety Standard; Engine Control Module Speed Limiter Device http://origin.www.gpo.gov/fdsys/pkg/FR - 2011 - 01 - 03/html/2010 - 33057.htm NHTSA. 2011. Fatality Analysis Reporting System (FARS) Analytical Users Manual 1975 - 2010 w ww - nrd.nhtsa.dot.gov/Pubs/811529.pdf North American Council for Freight Efficiency. 2010. Executive Report

– Wide Base Tires http://nacfe.org/LZdmQ/wp - content/uploads/2010/12/NACFE - ER - 1002 - Wide - Base Tires - Dec - 2010.pdf North American Council for Freight Efficiency. 2011. Speed limiters save money and fuel without significant productivity loss http://nacfe.org/wp content/uploads/2011/04/NACFE - ER - 1003 - Speed - Limiters - Mar - 2011.pdf Owings, S. 2012. Statement of Steve Owings, father of Cullum Owings, killed in a truck crash involving an inattentive and speeding trucker and president and co - founder, Road Safe Amercica (RSA) before the Subcommittee on Highways and Transit, Committee on Transportation and Infrastructure, U.S. House of Representatives http://republicans.transportation.house.gov/Media/file/TestimonyHighways/2012 - 09 - 13 - Owings.pdf Owner - Operator Independent Drivers Association. 2010. Comments of the owner - o perator independent drivers association, inc in response to a notice of intent, request for scoping comments [Docket No. NHTSA - 2010 - 0079] w ww.ooida.com/Issues&Actions/Regulatory/issues/docs/U.S.DOT NHTSA%20fuel%20mileage%20comments.pdf Palmer, D. L. 2012. Statement of Assistant Chief David L. Palmer President of Commercial Vehicle Safety Alliance before the Highways and Transit Subcommittee of the House Transportation and Infrastructure Committee on "Evaluating the effectivenes of DOT's truck and bus safety program" http://republican s.transportation.house.gov/Media/file/TestimonyHighways/2012 - 09 - 13 - Palmer.pdf138 Parish, R., Chen, P., & Gallo, J. - B. 2012. How drive cycle affects hybrid fuel economy and vehicle cost effectiveness w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26444 Patton, O. 2011. NHTSA clears path for speed - limiter proposal w ww.truckinginfo.com/n ews/news - detail.asp?news_id=72581 Purchase, E. 2011. Trucking Speed Governors: PA Semi Accident Lawyers on NHTSA Study w ww.yourerieaccidentlawyers.com/blog/2011/09/trucking - speed - governors - pa - semi accident - lawyers - on - nhtsa - study.shtml Renaud, P. S., & Coleman, D. 2012. Telematics: real - time fleet management and improved fuel economy w ww.ntea.com/worktruckshow/index.aspx?id=25469 Road Safe America. 2012. The Problem: Physics w ww.roadsafeamerica.org/docs/RSASpeedLimiter WhitePaper_0039.pdf Rocky Mountain Institute. RMI overview of Walmart Truck Fleet http://move.rmi.org/markets in - motion/case - studies/trucking/wal - mart - s - truck - fleet.html Samba, D., Park, B. B., & Gardner, B. 2011. Evaluation of Large - Truck Transportation Alternatives with Safety, Mobility, Energy, and Emissions Analysis http://trid.trb.org/view.aspx ?id=1092002 SmartDrive Systems. 2012. SmartDrive w ww.smartdrive.net/ Technical Advisory Service for Attorneys. 2010. Trucks and Truck Accidents: Considerations for Litigators w ww.tasanet.com/knowledgeCenterDetails.aspx?docTypeID=1&docCatID=4&docID=5 5 Toledo, T., Albert, G., & Hakkert, S. 2007. A Simulation - Based Evaluation of the Impact of Active Speed Limiters on Tr affic Flow and Safety http://pubsindex.trb.org/view.aspx?id=801530 Transport Canada. 2009. Summary Report - Assessment of a Heavy Truck Speed Limiter Requirement in Canada w ww.tc.gc.ca/eng/roadsafety/tp - tp14808 - menu - 370.htm Transport Topics. 2011. NHTSA to Propose Truck Speed Limiters w ww.ttnews.c om/articles/basetemplate.aspx?storyid=25848 Trucker News Services. 2012. Speed limiter report: Trucks with devices had 50% lower ‘speed limiter relevant’ crash rate w ww.thetrucker.com/News/Stories/2012/3/27/SpeedlimiterreportTruckswithdeviceshad5 0lowerspeed - limiterrelevantcrashrate.aspx TruckingInfo. 2012. Survey suggests 'connected fleet' is becoming the norm w ww.truckinginfo.com/news/news - detail.asp?news_id=76592 Tsao, H. - S. J. 2009. Drastic Productivity Gain for Large - Truck Operations with Automated Trailer Steering w ww.engr.sjsu.edu/media/pdf/res/coe_res_facdev_grant_symp_040309_tsao_ppt.pdf Vertical Alliance Group Inc. 2012. CSA 2010 BASIC Definitions and Data Sources for Carriers w ww.csa2010.com/articles/BASIC_Definitions_and_Data_Sources_for_Carriers.htm Vise, A. 2010. NHTSA to consider speed limiter rule in 2012 w ww.ccjdigital.com/nhtsa - plans to - consider - speed - limiter - rule - in - 2012/ Walkowicz, K. 2012. Medium and H eavy - D uty Vehicle Evaluations w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/veh_sys_sim/vss001_ walkowicz_2012_o.pdf139 Wall Street Journal. 2012. New York’s Schumer: GPS Guides Trucks into Crashes http://blogs.wsj.com/drivers - seat/2012/09/25/new - yorks - schumer - gps - guides - trucks - into crashes/ Walmart Trucking Fleet Overview . w ww.walmartstores.com/Sustainability/7674.aspx Whistler, D. 2012. Researchers sift through crash statistics http://fleetowner.com/safety/researchers - sift - through - crash - statistics?NL=FO 01&Issue=FO - 01_20120702_FO 01_251&YM_RID=james.macisaac@dot.gov&YM_MID=1323293 7.2 Regulatory Bibliography American Transportation Research Institute. 2012. Compendium of Idling Regulations w ww.atri - online.org/research/idling/ATRI_Idling_Cab_Card.pdf Califor nia Air Resources Board. 2009. Heavy - Duty Vehicle Idling Emission Reduction Program w ww.arb.ca.gov/msprog/truck - idling/truck - idling.htm California Air Resources Board. 2012a. Facts About Tractor - Trailer Greenhouse Gas Regulation Reducing Climate Change Emissions from Tractor - Trailers w ww.arb.ca.gov/cc/hdghg/fact_sheets/HDGHG_Genl_Fact_Sheet.pdf Cali fornia Air Resources Board. 2012b. Implementation Guidance for the Tractor - Trailer GHG Regulation w ww.arb.ca.gov/cc/hdghg/documents/modaeroguidev1.pdf California Department of Tran sportation. 2012. Truck Route Classifications in California w ww.dot.ca.gov/hq/traffops/trucks/routes/truck - routes.htm Casey, C. 2012. Standards Update for Commercial Vehicles w ww.sae.org/events/nevss/summit/2012_EV_Safety_Summit_casey.pdf Chart. 2009. Codes, Standards and Advisories Applicable to Natural Gas Vehicles w ww.nexgenfueling.com/t_codes.html Clift, T. 2012. Chrysler, Ford Join Toyota in Opposing Mexico's Fuel Economy, Emissions Proposal w ww.autonews.com/apps/pbcs.dll/article?AID=/20121114/OEM11/121119939/chrysler ford - join - toyota - in - opposing - mexicos - fuel - economy#axzz2OsJ9lag5 DOE Alternative Fuels Data Center. 2013. Laws and Incentives w ww.afdc.energy.gov/laws/search DOE EERE. 2006. Fact #411: February 13, 2006 States that Allow Longer Combination Vehicles w ww1.eere.energy.gov/vehiclesandfuels/facts/2006_fcvt_fotw411.html DOE EERE. 2013a. Federal Laws and Incentives for Idle Reduction w ww.afdc.energy.gov/fuels/ laws/3259/U.S. DOE EERE. 2013b. IdleBase http://cleancities.energy.gov/idlebase EPA. 2012. EPA and NHTSA Joint MD/HD Planning Meetings FHWA. 2000a. Comprehensive Truck Size and Weight Study Volume 2, Chapter 2 w ww.fhwa.dot.gov/reports/tswstudy/Vol2 - Chapter2.pdf FHWA. 2000b. Comprehensive Truck Size and Weight Study Volume 2, Chapter 3 w ww.fhwa.dot.gov/reports/tswstudy/Vol2 - Chapter3.pdf FHWA. 2003. Commercial Vehicle Size and Weight Program w ww.ops.fhwa.dot.gov/freight/sw/overview/inde x.htm140 FHWA. 2004a. Federal Size Regulations for Commercial Motor Vehicles http://ops.fhwa.dot.gov/freight/publications/size_regs_final_rpt/size_regs_fi nal_rpt.pdf FHWA. 2004b. Questions and Answers About Vehicle Size and Weight w ww.ops.fhwa.dot.gov/freight/sw/faqs/index.cfm FHWA. 2005. Aerodynamic Device Compliance with 23 CFR 658.16( b) (4) w ww.ops.fhwa.dot.gov/freight/sw/aerodevice23cfr65816.htm FHWA. 2010. Freight Facts and Figures 2010 http://ops.fhwa.dot.gov/freight/freight_analysis/nat_freight_stats/docs/10factsfigures/figu re3_4.htm FHWA. 2012. MAP - 21 Freight Provisions w ww.fhwa.dot.gov/planning/freight_planning/talking_freight/nov282012transcript.cfm FMCSA. 2002. DOT Sets Safety Requirements For Mexican Trucks, Buses in United States w ww.fmcsa.dot.gov/about/news/news - releases/2002/031402.htm FMCSA. 2007. NAFTA Demonstration Project w ww.fmcsa.dot.gov/intl - programs/nafta rules /new - mexrule.htm FMCSA. 2012. Research on the Safety Impacts of Speed Limiter Device Installations on Commercial Motor Vehicles: Phase II w ww.fmcsa.dot.go v/facts - research/research technology/report/Speed - Limiters.pdf Frittelli, J. 2012. Federal Freight Policy: An Overview w ww.fas.org/sgp/crs/misc//R42764.pdf Fuetsch, M. 2013. U.S. could spend $340 million for natural gas tax incentives http://trid.trb.org/view.aspx?id=1245149 Goodyear Truck Tires. 2013. Standards & Regulations w ww.goodyeartrucktires.com/pdf/resources/service - manual/Retread_S13_V.pdf Hosier, F. 2009. Compressed natural gas explosion injures workers; what safety regulations apply? w ww.safetynewsalert.com/compressed - natural - gas - explosion - injures - three - what osha - rules - apply/ Insurance Institute for Highway Safety. 2013. State Speed Limits w ww.iihs.org/laws/speedlimits.aspx Jacobs, R. 2012. Megabus faces challenge over weight limits w ww.ft.com/intl/cms/s/0/db379 6e0 - 6f78 - 11e1 - b368 - 00144feab49a.html#axzz20REf91qa Kilcarr, S. 2012. Weighing in on disc brakes w ww.equities.com/news/headline - story?dt=2012 - 11 - 08&val=691808&cat= tech Knight, C. 2010. What Happens When Your CNG Tanks Expire? w ww.government fleet.com/article/print/story/2010/05/what - happens - when - y our - cng - tanks - expire.aspx Kwan, Q. 2012. Safety Considerations Related to Commercial Vehicles Using Natural Gas w ww1.eere.energy.gov/cleancities/pdfs/ngvtf12_kwan.pdf Mexico Tru cker Online. 2002. NAFTA - U.S.DOT Regulations http://mexicotrucker.com/mexican - truck - docs/nafta - us - dot - regulations National Research Council. 1990. Appendix D Recommendat ions from Truck Weight Limits Study http://nap.edu/openbook.php?record_id=10382&page=256 National Shippers Strategic Transportation Council. 2012. Competing Bills on Truck Size and Weight Limits http://freightadvocacy.org/key - issues/truck - size - and - weight - limits NHTSA. 1995. FMVSS 303: Fuel System Integrity of Compressed Natural Gas (CNG) Vehicles w ww.nhtsa.gov/DOT/NHTSA/Vehicle%20Safety/Test%20Procedures/Associated%20Fil es/tp - 303 - 00.pdf141 NHTSA. 2004. FMVSS 138: Tire Pressure Monitoring Systems; Co ntrols and Displays . 49 CFR Part 571. w ww.nhtsa.gov/DOT/NHTSA/Rulemaking/Rules/Associated%20Files/TPMSfinalrule_6. pdf NHTSA. 2007a. 49 CFR Parts 571 & 58 5 w ww.nhtsa.gov/DOT/NHTSA/Rulemaking/Rules/Associated%20Files/ESC_FR_03_200 7.pdf NHTSA. 2007b. Laboratory test procedure for FMVSS No. 139 New Pneumatic R adial Tires for Light Vehicles w ww.nhtsa.gov/DOT/NHTSA/Vehicle%20Safety/Test%20Procedures/Associated%20Fil es/TP - 139 - 03.pdf NHTSA. 2009a. Comp ressed Hydrogen Cylinder Research and Testing In Accordance With FMVSS 304 w ww.nhtsa.gov/DOT/NHTSA/NVS/Crashworthiness /Alternative%20Energy%20Vehicle %20Systems%20Safety%20Research/811150.pdf NHTSA. 2009b. FMVSS 121: 49 CFR Part 571 Air Brake Systems w ww.nhtsa.g ov/DOT/NHTSA/Rulemaking/Rules/Associated%20Files/121_Stopping_Di stance_FR.pdf NHTSA. 2010. Grant of petition for rulemaking: Federal Motor Vehicle Safety Standard; Engine Control Module Speed Limiter Device http://origin.www.gpo.gov/fdsys/pkg/FR - 2011 - 01 - 03/html/2010 - 33057.htm NHTSA. 2011. FMVSS 305: Federal Motor Vehicle Safety Standards; Electric - Powered Vehicles; Electrolyte Spillage and Electrical Shock Protection w ww.nhtsa.gov/DOT/NHTSA/Vehicle%20Safety/Test%20Procedures/Associated%20Fil es/TP - 305 - 01.pdf NHTSA. 2012. Notice of proposed rulemaking: Electroni c Stability Control Systems for Heavy Vehicles w ww.nhtsa.gov/staticfiles/nvs/pdf/136_Hvy_Veh_ESC_NPRM.pdf NHTSA. 2013. Tire Regulations w ww.nhtsa.gov/Laws+&+Regulations/Tires NHTSA and EPA. 2011. Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium - and Heavy - Duty Engines and Vehicles; Final Rule w ww.gpo.gov/fdsys/pkg/FR - 2011 - 09 - 15/html/2011 - 20740.htm NREL. 2010a. Electric Vehicle and Infrastructure Codes and Standards Citations w ww.afdc.energy.gov/pdfs/48605.p df NREL. 2010b. Natural Gas Vehicle and Infrastructure Codes and Standards Citations w ww.afdc.energy.gov/pdfs/48611.pdf Office of Management and Budget. 1998. Circular No. A - 119 Revised w ww.whitehouse.gov/omb/circulars_a119 Raj, P. K., Hathaway, W. T., & Kangas, R. 1996. Design Guidelines for Bus Transit Systems Using Compressed Natural Gas as an Alternative Fuel http://trid.trb.org/view.aspx?id=461266 Schmidt, J. 2011. Could U.S. - Mexico agreement lead to cleaner and more efficient vehicles in Mexico? http://grist.org/article/2011 - 03 - 04 - could - us - mexico - agreement - on - cross - border trucking - lead - to/ State of New Hampshire. 2013. AN ACT relative to weight of commercial vehicles with idle reduction devices w ww.gencourt.state.nh.us/legislation/2013/HB0196.html142 Tranportation Environmental Resource Center. 2013. Tranportation Environmental Resource Center List of State Regulations and Incentives for Alternativ e Fuels w ww.tercenter.org/pages/altfuelMA.htm Trucking.org. 2008. State Weight Exemptions (As of March 2008) w ww.trucking.org/AdvIssues/Advocacy%20Materials/State%20Weight%20Exemptions %20Table.pdf UnsafeTrucks.org. 2008. NAFTA Regulations on Safety http://unsafetrucks.org/nafta.htm Wall St reet Journal. 2012. New York’s Schumer: GPS Guides Trucks into Crashes http://blogs.wsj.com/drivers - seat/2012/09/25/new - yorks - schumer - gps - guides - t rucks - into crashes/ 7.3 Green Vehicle Deployment Bibliography ABI Research. 2009. Commercial Hybrid Vehicles: A Global Analysis of Medium - and Heavy Duty Hybrid Trucks and Buses w ww.abiresearch.com/research/product/1009888 - hybrid and - electric - vehicles/ Addison, J. 2010. UPS Fleet Hybrid Delivery Trucks and CNG w w w.cleanfleetreport.com/ups fleet - hybrid - delivery - trucks/ Alliance Autogas. 2012. Alliance Autogas: powered by propane right here, right now w ww.ntea.com/WorkArea/linkit .aspx?LinkIdentifier=id&ItemID=26458 American Public Transportation Association. 2012. Transit on the Cutting Edge of Clean Technology w ww.apta.com/resources/st atistics/Documents/Transit - Clean Technology.pdf Barnitt, R. 2011. FedEx Express Gasoline Hybrid Electric Delivery Truck Evaluation: 12 - Month Report w ww.nrel.gov/docs/fy11osti/48896.pdf Bennett, S . 2008. Alliant Switches Fleet Vehicles to Biofuels w ww.worktruckonline.com/Channel/Fuel - Management/Ar ticle/Story/2008/07/Alliant Switches - Fleet - Vehicles - to - Biofuels.aspx?prestitial=1 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities w ww1.eere.energy.gov/cleancities/pdfs/propanepaper09_final.pdf Boesel, J. 2012. Why now is the right time to diversify your portfolio...and help make the nation stronger and better www.ntea.com/WorkArea/linkit.aspx/LinkIdentifier=id%26ItemID=26495&ei=NFXzT4 6ZKsjZ6wHFqNyqCA&usg=AFQjCNFrhMcO367FTlOU.S.am1zicJn3vvyg Bolton, P. 2012. New York State - wide Alter native Fuel Vehicle Program for Vehicles and Fueling Stations w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2 012/technology_integration /arravt053_ti_bolton_2012_o.pdf Business Wire. 2012. CleanFUEL U.S.A and Collins Bus Corporation Deliver More than 100 Propane Autogas - Powered Buses w ww.businesswire.com/news/home/20121114005626/en/CleanFUEL - U.S.A - Collins Bus - Corporation - Deliver - 100 California Air Resources Board. 2012. Heavy - Duty (Tractor - Trailer) Greenhouse Gas Regulation w ww.arb.ca.gov/cc/hdghg/hdghg.htm143 California Natural Gas Vehicle Coalition. 2012. CEC Awards More than $8.5 Million: AB 118 buy - down funds go largely to NGVs for vehicles in all classes; more funds may be in the offing w ww.cngvc.org/pdf/newsletters/CalNGVNews_040212.pdf CalStart. 2012a. Best Fleet Uses, Key Challenges, and the Early Business Case for E - Trucks w ww.calstart.org/Libraries/E Truck_Task_Force_Documents/Best_Fleet_Uses_Key_Cha llenges_and_the_Early_Busin ess_Case_for_E - Trucks_Findings_and_Recommendations_of_the_E Truck_Task_Force.sflb.ashx CalStart. 2012b. Leading Fleets Take Delivery of World’s First Commercially Available Hybrid Hydraulic Parcel Delivery Trucks

– Hybrids Witho ut Batteries w ww.calstart.org/news_and_publications/CALSTART - in - the - news/CALSTART - Press Releases/wo rlds - first - hybrid - hydraulic - delivery - trucks.aspx CalStart. 2012c. Market Demand Analysis For Hybrid and Electric Trucks 2012 - 2016 Carbon War Room Research & Intelligence Group. 2012. Unlocking fuel - saving technologies in trucking and fleets http://carbonwarroom.com/sites/default/files/reports/Unlocking%20Fuel%20Saving%20 Technologies%20in%20T rucking%20and%20Fleets%20(Carbon%20War%20Room).pdf Chandler, K., Norton, P., & Clark, N. 2001. Waste Management's LNG Truck Fleet Final Results w ww.afdc.energy.gov/pdfs/waste_lng_final.pdf Clay, K. 2012. Transforming Transportation Globally The Role of Natural Gas w ww.sae.org/events/gim/presentations/2012/kclay.pdf Coca - Cola. 2011. 2010/2011 Sustainability Report w ww.thecoca colacompany.com/sustainabilityreport/downloads.html Composites World. 2007. New hybrid electric bus takes advantage of composites w ww.compositesworld.com/articles/new - hybrid - electric - bus - takes - advantage - ofcomposites Cornils, H. 2009. Hybrid Solutions for MD Commercial Vehicles w ww.erc.wisc.edu/documents/symp09 - Cornils.pdf County of Fairfax. 2012. County of Fairfax, VA fleet summary w ww.ntea.com/WorkAr ea/linkit.aspx?LinkIdentifier=id&ItemID=26463 DOE Alternative Fuels Data Center. 2012. Maine Fleets Make Progress with Propane w ww.afdc.energy.gov/case/1207 DOE EERE. 2011a. Project Results: Evaluating FedEx Express Hybrid - Electric Delivery Trucks w ww.nrel.gov/docs/fy11osti/50042.pdf DOE EERE. 2011b. Project Startup: Evaluating Coca - Cola’s Class 8 Hybrid - Electric Delivery Trucks w ww.nrel.gov/docs/fy11osti/49621.pdf DOE EERE. 2012a. Largest U.S. Port Complex Embraces LNG for Heavy - Duty Trucks w ww.afdc.energy.gov/case/1203 DOE EERE. 2012 b. National Clean Fleets Partnership w ww1.eere.energy.gov/cleancities/national_partnership.html DOE EERE. 2013. Propane: Liquefied Petroleum Gas (LPG) http://fueleconomy.gov/feg/lpg.shtml Ebert, R. D. 2012. Long Island Regional Energy Collaborative: Promoting a Green Economy through Clean Transportation Alternatives w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration /arravt052_ti_ebert_2012_o.pdf144 Energy Information Administration. 2010. How many alternative fu el and hybrid vehicles are there in the U.S.? w ww.eia.gov/tools/faqs/faq.cfm?id=93&t=4 Environmental Leader. 2011. UPS Adds to its Natural Gas Truck Fleet w ww.environmentalleader.com/2011/02/25/ups - adds - to - its - natural - gas - truck - fleet/ EPA. 2011. 2011 SmartWay Champions w ww.epa.gov/smartway/partner resources/2011champions.htm Feinberg, C. 2012. NJ compressed natural gas refuse trucks, shuttle buses and infrastructure (NJ Clean Cities Coalition) w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration /arravt051_ti_feinberg_2012_o.pdf Fleets & Fuels Newsletter. 2012. Five More EVI Medium Trucks for Frito - L ay w ww.showtimesdaily.com/news - articles/five - more - evi - medium - trucks - for - frito - lay Freightliner. 2012. Freightliner hybrid trucks w ww.cleanandgreenvehicles.com/pdfs/M2eHybrid Brochure.pdf Garthwaite, J. 2011. Trading Oil for Natural Gas in the Truck Lane http://news.nationalgeographic.com/news/energy/2011/09/110902 - natural - gas - fuel - for trucks/ Gartner, J., & Wheelock, C. 2009. Electric Vehicles: 10 Predictions for 2010 w ww.pikeresearch.com/research/electric - vehicles - 10 - predictions - for - 2010 General Services Administration. 2011. Electric Vehicle Pilot Program w ww.gsa.gov/portal/ content/281581 Green Car Congress. 2012. Four new corporate partners join DOE National Clean Fleets Partnership w ww.greencar congress.com/2012/03/four - new - corporate - partners - join - doe national - clean - fleets - partnership.html Greer, M. 2012. Altec Green Fleet Work Truck Electrification: Leveraging the Ultimate Clean Fuel w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26465 Hybrid Truck Users Forum. 2012a. More Parker Hannifin Hydraulic Hybrids http://issuu.com/kfetzer/docs/showtimes_htuf2012_issuu?mode=window&viewMode=do ublePage Hybrid Truck Users Forum. 2012b. XL Hybrids is Using JCI Battery Packs http://issuu.com/kfetzer/docs/showtimes_htuf2012_issuu?mode=window&viewMode=do ublePage Kaye, L. 2012. UPS Rolls Out Lightweight Composite Trucks In a Move Towards Energy Efficiency w ww.triplepundit.com/2012/06/ups - composite - trucks - energy - efficiency/ Kemp, J. 2012. U.S. post office struggles with alternative fuel delivery w ww.reuters.com/article/2012/05/28/us - column - kemp - us - postal - service idU.S.BRE84R0GM20120528 Kerkhof, A. 2011. Fuel & Traction Systems Observatory - HYBRIDS http://hybriduserforum.eu/wp - content/uploads/2011/05/110526 - HUF_UITP - Arno_Kerkhof.pdf Lammert, M. 2009. Twelve - Month Evaluation of UPS Diesel Hybrid Electric Delivery Vans w ww.nrel.gov/docs/fy10osti/44134.pdf Levy, M. 2011. Pa. House GOP wants more natural gas buses, trucks w ww.businessweek.com/ap/financialnews/D9MEBLF80.htm145 Lowe, M., Ayee, G., & Gereffi, G. 2009. Manufacturing Climate Solutions Carbon - Reducing Technologies and U.S. Jobs: Hybrid Drivetrains for Medium - and Havy - Duty Trucks w ww.cggc.duke.edu/environment/climatesolutions/greeneconomy_Ch9_HybridDrivetrai nsforTrucks.pdf Lynn, K. 2012. 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– Major Findings http://nacfe.org/wp - content/uploads/2013/03/2013 - NACFE - Study - Major Findings - 030713.pdf NREL. 2010. Idle reducti on: fleet test and evaluation w ww.nrel.gov/vehiclesandfuels/fleettest/research_truck_idle.html NREL. 2011. Fleet Test and Evaluation w ww.nrel.gov/vehiclesandfuels/fleettest/ Office of the Press Secretary. 2011. Presidential Memorandum -- Federal Fleet Performance w ww.whitehouse.gov/the - press - office/2011/05/24/presidential - memorandum - Federal fleet - performance Oil and Gas Journal. 2012. LNG seen viable fuel for heavy - duty trucks w ww.ogj.com/articles/2012/06/lng - seen - viable - fuel - for - heavy - duty - trucks.html Orange County Business Council. Projected Outlook for Next Generation and Alternative Transportation Fuels in California 2010 - 2030 w ww.fuelingcalifornia.org/wpcms/wp content/uploads/fueling - ca - next - gen - alt - fuels - final - may - 2011.pdf Parish, R., Chen, P., & Gallo, J. - B. 2012. How d rive cycle affects hybrid fue economy and vehicle cost effectiveness w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26444 Parish, R., & Gallo, J. - B. 2012. H TUF Class 8b Working Group w ww.calstart.org/projects/htuf/htuf - blog/12 - 03 - 12/Class_8_Working_Group_Update.aspx146 PikeResearch. 2009. Nearly 4 Million H ybrid Vehicles to be Purchased by Fleet Managers through 2015 w ww.pikeresearch.com/newsroom/nearly - 4 - million - hybrid - vehicles - to - be purchased - by - fleet - managers - through - 2015 Propane Education and Research Council. 2013. Propane Exceptional Energy http://autogasusa.org/ Proterra, I. 2009. Proterra Brings Future of Green Commercial Transit to California Cities With Zero Emission Clean Bus Tour w ww.prweb.com/releases/2009/02/prweb1968224.htm Rocky Mountain Institute. RMI overview of Walmart Truck Fleet http://move.rmi.org/markets in - motion/case - studies/trucking/wal - mart - s - truck - fleet.html Saltzgiver, S. 2012. 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Safety Warning: Acid Exposure of Vehicular CNG Cylinders w ww.ngvglobal.com/safety - warning - acid - exposure - of - vehicular - cng - cylinders - 0911 Levy, M. 2011. Pa. House GOP wants more natural gas buses, trucks w ww.businessweek .com/ap/financialnews/D9MEBLF80.htm Linde North America. 2012. Linde Launches Online Resource to Help Fleets Make the Switch to LNG w ww.worktruckonline.com/Channel/Fuel -166 Management/News/Story/2012/07/Linde - Launches - Online - Resource - to - Help - Fleets Make - the - Switch - to - LNG.aspx Lowe, M., Ayee, G., & Gereffi, G. 2009. Manufacturing Climate Solutions Ca rbon - Reducing Technologies and U.S. Jobs: Hybrid Drivetrains for Medium - and Heavy - Duty Trucks w ww.cggc.duke.edu/environment/climatesolutio ns/greeneconomy_Ch9_HybridDrivetrai nsforTrucks.pdf Lux Research. 2012. Searching for Innovations to Cut Li - ion Battery Costs https://portal.luxresearchinc.com/research/report_excerpt/10150 Ly, H. 2011. Closing the Safety Loop Secures NGV Fleet Investment w ww.ngvglobal.com/closing - the - safety - loop - secures - ngv - fleet - investment - 0309 Lynn, K. 2012. SANBAG/Ryder Natural Gas Vehicle Project w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration /arravt044_ti_lynn_2012_o.pdf Macaione, D. P. 1992. Flammabili ty characteristics of fiber - reinforced epoxy composites for combat vehicle applications w ww.dtic.mil/cgi bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA256844 M assDEP. 2012. Massachusetts Environmental Officials Announce Federal Grants to Fund Diesel Hybrid Trucks, Promoting Cleaner Air Quality w ww.mass.gov/dep/public/press/0412dies.htm Mathers, J. 2011a. Hybrid Trucks: Creating Jobs, Reducing Emissions http://blogs.edf.org/innovation/2011/01/31/hybrid - trucks - creating - jobs - reducing emissions/ M athers, J. 2011b. Work Trucks and Fuel Consumption: 2011 http://blogs.edf.org/innovation/2011/03/10/work - trucks - and - fuel - consumption - 2011/ Mekhiche, M. 2012. HybriDrive parallel propulsion system: BAE Systems solution for heavy duty vocational trucks w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26473 Mills, R. 2011. TPS investigates claims that CNG - fueled buses made bus drivers sick; The district says it checked out all 140 CNG buses in its fleet w ww.krmg .com/news/news/local/tps - investigates - claims - cng - fueled - buses - made - bus - /nFhNq/ Mintz, M. R. W. D. S. A. B. M. 2010. Natural Gas Vehicles: Status, Barriers, and Opportunities w ww.afdc.energy.g ov/pdfs/anl_esd_10 - 4.pdf Morgenstern, M. 2012. Propane tank explodes in McDonald's drive - through w ww.theblaze.com/stories/propane - tank - explodes - in - mcdonalds - d rive - through/ Moriarty, K. 2012. DOE Online Tools for Alternative Fuels w ww.sae.org/events/gim/presentations/2012/kristi_moriarty.pdf Motavalli, J. 2012. Making the case for propane: from gas grills to cars and trucks w ww.cartalk.com/content/making - case - propane - gas - grills - cars - and - trucks National Biodiesel Board. 2009a. B100 Mater ial Compatibility w ww.biodiesel.org/docs/ffs performace_usage/materials - compatibility.pdf?sfvrsn=4 National Biodiesel Board. 2009b. Biodiesel sample mat erial safety data sheet w ww.biodiesel.org/extpages/search - results?q=msds National Fire Protection Association. 2011. NFPA 58: Liquiefied petroleum gas code w ww.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=58&cookie_test=1167 National Petroleum Council. 2012a. Advancing Technology for America’s Transportation Future, Chapter 7: Infrastructure w ww.npc.org/FTF - report - 080112/Ch7 - Infrastructure 080112.pdf National Petroleum Council. 2012b. An Initial Qualitative Discussion on Safety Considerations for LNG Use in Transpor tation w ww.npc.org/FTF_Topic_papers/19LNG_Transportation.pdf National Petroleum Council. 2012c. NPC Future Transportation Fuels Study: Advancing Technology for America’s Transport ation Future w ww.npc.org/FTF - 80112.html Natural Gas Transit Users Group. 2007. TUG Tidbits w ww.cleanvehicle.org/committee/g as transit/tugtidbits907.pdf Natural Gas Vehicle Owner Community. 2011. CNG tanks never expire? http://cngchat.com/forum/archive/index.php/t - 7264.html Natural Gas Vehicles for America. 2012. NGVs and the Environment w ww.ngvc.org/about_ngv/ngv_environ.html News On 6. 2012. Broken Arrow Police: Business Owner Killed When CNG Tank Explodes w ww.newson6.com/story/17393515/broken - arrow - police - call - mans - death - accidential death NGV Journal. 2011. National NGV Fleet Forum forms in the United States w ww.ngvjournal.com/en/vehicles/item/5048 - national - ngv - fleet - forum - forms - in - the united - states NHTSA. 1995. FMVSS 303: Fuel System Integrity of Compressed Natural Gas (CNG) Vehicles w ww.nhtsa.gov/DOT/NHTSA/Vehicle%20Safety/Test%20Procedures/Associated%20Fil es/tp - 303 - 00.pdf NHTSA. 2009a. Compressed Hydrogen Cylin der Research and Testing In Accordance With FMVSS 304 w ww.nhtsa.gov/DOT/NHTSA/NVS/Crashworthiness/Alternative%20Energy %20Vehicle %20Systems%20Safety%20Research/811150.pdf NHTSA. 2009b. FMVSS 304 CNG fuel container integrity w ww.nhtsa.go v/DOT/NHTSA/NVS/Crashworthiness/Alternative%20Energy%20Vehicle %20Systems%20Safety%20Research/811150.pdf NHTSA. 2012. Electric Vehicle Safety Technical Symposium www.nhtsa.gov/ staticfiles/nvs/pdf/EV_Symposium_agenda.pdf Office of the Press Secretary. 2011. Presidential Memorandum -- Federal Fleet Performance w ww. whitehouse.gov/the - press - office/2011/05/24/presidential - memorandum - Federal fleet - performance Oil and Gas Journal. 2012. LNG seen viable fuel for heavy - duty trucks w ww.ogj.com/articles/2012/06/lng - seen - viable - fuel - for - heavy - duty - trucks.html Overdrive. 2012. DOE pushing technologies to boost fuel efficiency w ww.ove rdriveonline.com/doe - pushing - technologies - to - boost - fuel - efficiency/ Parish, R., Chen, P., & Gallo, J. - B. 2012. How drive cycle affects hybrid fuel economy and vehicle cost effectiveness w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26444 PepsiCo. 2011. Frito - Lay Electric Delivery Trucks hit the Green Streets of Orlando w ww.pepsico.com/PressRelease/Frito - Lay - Electric - Delivery - Trucks - Hit - the - Green Streets - of - Orlando12022011.html168 PikeResearch. 2010. Hybrid Electric Vehicles for Fleet Markets w ww.pikeresearch.com/research/hybrid - electric - vehicles - for - fleet - markets Pratt, C. 2011. Terex HyPower Hybrid System Approved by CARB w ww.terexhypower.com/environment/terex%C2%AE - hypower%E2%84%A2 - hybrid system - approved - by - california - air - resources - board/ Propane Education and Research Council. 2013. Propane Exce ptional Energy http://autogasusa.org/ Raj, P. K., Hathaway, W. T., & Kangas, R. 1996. Design Guidelines for Bus Transit Systems Using Compressed Natural Gas as an Alternative Fuel http://trid.trb.org/view.aspx?id=461266 Reich, S. L., & Kolpakov, A. 2011. Tracking Costs of Alternatively Fueled Buses in Florida w ww.nctr.usf.edu/2011/12/tracking - costs - of - alternatively - fueled - buses - in - florida - 2/ Rolander, N., Matson, D., & Chernicoff, W. P. 2003. Materials Investigation of Thermal Triggers Used in Pressure Relief Devices on Transit Buses http://volpedb.volpe.dot.gov/outside/owa/vntsc_outside.product_repository.display_item? p_doc_id=28777 Saltzgiver, S. 2012. Successful fleet strategies for deployin g clean vehicles w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26470 Smith Electric Vehicles. 2012. Smith NTEA Green Truck Summit w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26498 Trucking.org. 2008. State Weight Exemptions (As of March 2008) w ww.trucking.org/AdvIssues/Advocacy%20Materials/State%20Weight%20Exemptions %20Table.pdf TruckingInfo. 2012. Eaton enhances hybrid drive system for faster payback w ww.truckinginfo.com/news/news - detail.asp?news_id=77134 Turnure, J. 2012. Annual Energy Outlook 2012 Fuel Demand in the Transportation Sector w ww. eia.gov/pressroom/presentations/turnure_06272012.pdf Veolia Environmental Services. 2012. Veolia's CNG Fleet w ww.veoliaes.com/en/about us/features/cng - fleet.html Via Motors. 2012. 2012 National Fleet Electrification Web Conference: speaker lineup w ww.viamotors.com/events/2012 - nfec/ Voelcker, J. 2012. Ford F - 750 Plug - In Hybrid Work Truck: Not Your Little Leaf, Sonny w ww.greencarreports.com/news/1073783_ford - f - 750 - plug - in - hybrid - work - truck - not your - little - leaf - sonny Wald, M. 2011. U.P.S. Finds a Substitut e for Diesel: Natural Gas, at 260 Degrees Below Zero http://green.blogs.nytimes.com/2011/02/22/u - p - s - finds - a - substitute - for - diesel - natural gas - at - 260 - degrees - below - zero/ Walkowicz, K. 2012a. MD PHEV/EV ARRA Project, Data Collection and Reporting w ww.nrel.gov/vehiclesandfuels/fleettest/pdfs/53878.pdf Walkowicz, K. 2012b. Medium and Heavy Duty Vehicle Evaluations w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/veh_sys_s im/vss001_ walkowicz_2012_o.pdf Warner, F. 2012. New electric truck catches fire twice in Allentown http://a rticles.mcall.com/2012 - 02 - 08/news/mc - allentown - electric - truck - fire 20120208_1_electric - truck - lithium - ion - batteries - truck - box169 Watkins, L. 2012. UPS Ontario - Las Vegas LNG Corridor Extension Project: Bridging the Gap w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/technology_integration /arravt047_ti_watkins_2012_o.pdf Watt, G. M. 2001. Natural Gas Vehicle Tr ansit Bus Fleets: The Current International Experience http://apvgn.pt/documentacao/iangv_bus%20fleets.pdf Westport HD. 2012. Servicing Heavy - Duty Natural Gas Trucks: Preparation And Shop Requirements w ww.automotiveworld.com/webinars/servicing - heavy - duty - natural - gas trucks - preparation - and - shop - requirements/ Whit e, V. 2012. Heavy - Duty Natural Gas Drayage Truck Replacement Program w ww1.eere.energy.gov/vehiclesandfuels/pdfs/merit_re view_2012/technology_integration /arravt045_ti_white_2012_o.pdf Whyatt, G. 2010. Issues Affecting Adoption of Natural Gas Fuel in Light - and Heavy - Duty Vehicles ht tp://s3.amazonaws.com/zanran_storage/www.pnl.gov/ContentPages/184758856.pdf Wilson, K. 2012. SAE Cooperative Research Project to Develop Repeatable Safety Performance Test Procedures for Rechargeable Energy Storage Systems (RESS) w ww.sae.org/events/nevss/summit/2012_EV_Safety_Summit_wilson.pdf Wise Gas. 2012. Wise Gas: CNG Cylinder Safety w ww.wisegasinc.com/ wg - cylindersafety.htm Wong, J. 2009. CNG & Hydrogen Tank Safety, R&D, and Testing w ww1.eere.energy.gov/hydrogenandfuelcells/pdfs/cng_h2_workshop_8_wong.pdf Wo rk Truck Magazine. 2010. Clean Energy Announces Expansion of Southern California LNG Fueling Infrastructure w ww.worktruckonline.com/Channel/Green Fleet/News/Story/2010/03/Clean - Energy - Announces - Expansion - of - Southern - California LNG - Fueling - Infrastructure.aspx Work Truck Magazine. 2011. Waste Management Adds 1,000th Natural Gas Truck to F leet w ww.worktruckonline.com/Channel/Fuel - Management/News/Story/2011/07/Waste Management - Adds - 1 - 000th - Nat ural - Gas - Truck - to - Fleet.aspx Work Truck Magazine. 2012. Green Energy Oilfield Services Builds Green Truck Fleet w ww.worktruckonli ne.com/News/Story/2012/02/Green - Energy - Oilfield - Services - Builds Green - Truck - Fleet.aspx Yacobucci, B. D. 2008. Natural Gas Passenger Vehicles: Availability, Cost, and Performance w ww.policyarchive.org/handle/10207/bitstreams/19063.pdf Zalosh, R. 2009. CNG and Hydrogen Vehicle Fuel Tank Failure Incidents, Testing, and Preventive Measures w ww.mvfri.org/Contracts/Final%20Reports/CNGandH2VehicleFuelTankPaper.pdf
7.6 Fuel Efficiency Technology Bibliography ABI Research. 2009. Commercial Hybrid Vehicles: A Global Analysis of Medium - and Heavy Duty Hybrid Trucks and Buses w ww.abiresearch.com/mobile/research/1001997 Adams, R. 2010a. CNG Transit Experience Survey w ww1.eere.energy.gov/cleancities/pdfs/ngvtf10_trans_lessons_learned.pdf Adams, R. 2010b. CNG Transit Experience Survey (Clean Vehicle Education Foundation) w ww1.eere.energy.gov/cleancities/pdfs/ngvtf10_trans_lessons_learned.pdf170 Adams, T., Kleinmaier, D., Marach, A., Helfrich, G., Levine, J., & Bittner, J. 2012. Longer Combination Vehicles: An Estimation of their Benefits and Public Perception of The ir Use www.wistrans.org/cfire/.../CFIRE_05 - 01_Final_Report.pdf Altec Industries. 2012. Altec Green Fleet w ww.altec.com/green - fleet.php American Transportation Research Institute. 2011. Predicting Truck Crash Involvement: A 2011 Update w ww.atri online.org/research/results/ ATRI_Crash_Predictor_One_Pg_Summary_Apr_2011.pdf American Trucking Association. 2009. Expanding ATA’s Safety Agenda Executive Summary w ww.truckline.com/New sroom/Policy%20Papers/Safety%20Task%20Force%20Report.p df BAE Systems. 2012. The Heavy - Duty Hybrid w ww.hybridrive.com/ Barry, K. 2012. Induction Charging Comes to Public Transit w ww.wired.com/autopia/2012/12/induction - charging - bus/ Beegle, B. 2012. Worksite idle reduction w ww.ntea.com/WorkArea/linkit.asp x?LinkIdentifier=id&ItemID=26496 Bennett, S. 2008. Alliant Switches Fleet Vehicles to Biofuels w ww.wo rktruckonline.com/Channel/Fuel - Management/Article/Story/2008/07/Alliant Switches - Fleet - Vehicles - to - Biofuels.aspx?prestitial=1 Bertram, M. R. W. A. B. K. 2010. Propane Vehicles: Status, Challenges, and Opportunities w ww1.eere.energy.gov/cleancities/pdfs/propanepaper09_final.pdf Biodiesel Magazine. 2012. Mack and Volvo Trucks join growing list of B20 supporters w ww.biodieselmagazine.com/articles/8470/mack - and - volvo - trucks - join - growing - list - ofb20 - supporters Brecher, A. 2007. A Safety Roadmap for Future Plastics and Composites Intensive Vehicles w ww.nhtsa.gov/DOT/NHTSA/NVS/Crashworthiness/Vehicle%20Aggressivity%20and% 20Fleet%20Compatibility%20Research/810863.pdf Britis h Columbia Ministry of Transportation and Infrastructure. 2011. Long Combination Vehicles Program w ww.th.gov.bc.ca/cvse/lcv/faqs.htm Business Wire. 2012. CleanFUEL USA and Collins Bus Corporation De liver More than 100 Propane Autogas - Powered Buses w ww.businesswire.com/news/home/20121114005626/en/CleanFUEL - USA - Collins - Bus Corporatio n - Deliver - 100 California Air Resources Board. 2012. Heavy - Duty (Tractor - Trailer) Greenhouse Gas Regulation w ww.arb.ca.gov/cc/hdghg/hdghg.htm California Department of Transportation. 2009. Longer Com bination Vehicles w ww.dot.ca.gov/hq/traffops/trucks/exemptions/lcvs.htm California Natural Gas Vehicle Coalition. 2012. Cummins Plans 15 - Liter HD Engine w ww.cngvc.org/pdf/newsletters/CalNGVNews_041612.pdf CalStart. 2012a. Best Fleet Uses, Key Challenges, and the Early Business Case for E - Trucks w ww.calstart.org/Libraries/E Truck_Task_Force_Documents/Best_Fleet_Uses_Key_Challenges_and_the_Early_Busi n ess_Case_for_E - Trucks_Findings_and_Recommendations_of_the_E Truck_Task_Force.sflb.ashx CalStart. 2012b. Leading Fleets Take Delivery of World’s First Commercially Available Hybrid Hydraulic Parcel Delivery Trucks

– “Hybrids Without Batteries”171 w ww.calstart.org/news_and_publications/CALSTART - in - the - news/CALSTART - Press Releases/worlds - first - hybrid - hydrau lic - delivery - trucks.aspx CalStart. 2012c. Market Demand Analysis For Hybrid and Electric Trucks 2012 - 2016 CalStart. 2012d. Wrightspeed brings a CNG plug - in http://issuu.com/kfetzer/docs/showtimes_htuf2012_issuu?mode=window&viewMode=do ublePage Carbon War Room Research & Intelligence Group. 2012. Unlocking fuel - saving technologies in trucking and fleets http://carbonwarroom.com/sites/default/files/reports/Unlocking%20Fuel%20Saving%20 Technologies%20in%20Trucking%20and%20Fleets%20(Carbon%20War%2 0Room).pdf Cascade Sierra Solutions. 2011. Shorepower Truck Electrification Project www.the - step project.org/green - answers/fleet - managers/ City of Portland. 2007. Improving Bicy cle Safety in Portland www.portlandonline.com/shared/cfm/image.cfm?id=191337 Clark, K. C. P. N. N. 2001. Waste Management's LNG Truck Fleet Final Results w ww.afdc.energy.gov/pdfs/waste_lng_final.pdf Clean Vehicle Education Foundation. 2010. How Safe are Natural Gas Vehicles? w ww.cleanvehicle.org/committee/technical/PDFs/Web - TC - TechBul2 - Safety.pdf Clean Vehicle Education Foundation. 2012. Fatal accident removing cylinder solenoid valve w ww.cleanvehicle .org/technology/ValveFatality.pdf CNG Chat. 2009. CNG Tank Failure in Los Angeles http://cngchat.com/forum/archive/index.php/t - 4581.html Cogan, R. 2012. How to Avoid Problems When Usin g Biodiesel w ww.ehow.com/how_2118859_avoid - problems - using - biodiesel.html Composites World. 2007. New hybrid electric bus takes advantage of composites w ww.compositesworld.com/articles/new - hybrid - electric - bus - takes - advantage - ofcomposites Construction Business Owners 2012. Hino Trucks Honored at Biodiesel Conference w ww.constructionbusinessowner.com/topics/hino - trucks - honored - biodiesel - conference Construction Business Owners. 2012. Hino Trucks Honored at Biodiesel C onference w ww.constructionbusinessowner.com/topics/hino - trucks - honored - biodiesel - conference Cookson, R., & Knight, I. 2010. Sideguards on heavy goods v ehicles Cornils, H. 2009. Hybrid Solutions for MD Commercial Vehicles w ww.erc.wisc.edu/documents/symp09 - Cornils.pdf DeCoster, T. 2012. Parker's hydraulic hybrid technologies w ww.ntea.com/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=26445 DOE. 2012. Energy Department Investments to Develop Lighter, Stronger Materials for Greater Vehicle Fuel Economy w ww.doe.gov/articles/energy - department - investments - develop lighter - stronger - materials - greater - vehicle - fuel DOE Alternative Fuels Data Center. 2010. Propane Tank Overfill Safety Advisory w ww.afdc.energy.gov/technology_bulletin_1008.html DOE Alternative Fuels Data Center. 2012. Biodiesel Blends w ww.afdc.energy.gov/fuels/biodiesel_blends.html DOE Alternative Fuels Data Center. 2013a. Laws and Incentives w ww.afdc.energy.gov/laws/search DOE Al ternative Fuels Data Center. 2013b. Propane w ww.afdc.energy.gov/fuels/propane.html172 DOE EERE. 2006. Fact #411: February 13, 2006 States that Allow Longer Combination Vehicles w ww1.eere.energy.gov/vehiclesandfuels/facts/2006_fcvt_fotw411.html DOE EERE. 2011. Project Startup: Evaluating Coca - Cola’s Class 8 Hybrid - Electric Delivery Trucks w ww.nrel.gov/docs/fy11osti/49621.pdf DOE EERE. 2012a. Alternative Fuels and Advanced Vehicles Data Center w ww.afdc.energy.gov/afdc/fuels/natural_gas. html DOE EERE. 2012b. Idle Reduction Research and Development w ww.afdc.energy.gov/afdc/vehicles/idle_reduction_research.html DOE EERE. 2012c. Largest U.S. Port Complex E mbraces LNG for Heavy - Duty Trucks w ww.afdc.energy.gov/case/1203 DOE EERE. 2012d. National Clean Fleets Partnership w ww1.ee re.energy.gov/cleancities/national_partnership.html Eaton. 2011. Eaton Hybrid Electric Power Systems Emergency Response Guide TRDR1100 w ww.roadranger.com/rr/CustomerSupport/Support/LiteratureCenter/index.htm?litlibtarge t=1162919212387 Ehlich, T. 2012. Sideguards

– Background and Facts w ww.safetrucks.ca/wp content/uploads/2012/02/Olivia_Chow_Presentation_Truck_Sideguards_2012 - 02 - 23.pptx Energy Information Administration. 2010. How many alternative fuel and hybrid vehicles are there in the U.S.? w ww.eia.gov/tools/faqs/faq.cfm?id=93&t=4 Environmental Leader. 2011. UPS Adds to its Natural Gas Truck Fleet w ww.environmentalleader.com/2011/02/25/ups - adds - to - its - natural - gas - truck - fleet/ EPA. 2004. Smatway: a glance at clean freight strategies: single wide - based tires http://nepis.epa.gov/Exe/ZyNET.exe/P100AGGD.TXT?ZyActionD=ZyDocument&Clien t=EPA&Index=2000+Thru+2005&Docs=&Query=&Time=&EndTime=&SearchMethod =1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFiel dDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&F ile=D%3A%5Czyfiles%5CIn dex%20Data%5C00thru05%5CTxt%5C00000027%5CP100AGGD.txt&User=ANONY MOUS&Password=anonymous&SortMethod=h%7C - &MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i 425&Display=p%7Cf&DefSeekPage=x&SearchBack=ZyActionL&Back =ZyActionS&B ackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL EPA. 2011a. EPA Smartway Longer Combination Vehicle Factsheet w ww.epa.gov/smartway/documents/partnership/trucks/partnership/techsheets truck/EPA420F10 - 053.pdf EPA. 2011b. SmartWay Technology Program: Verified Aerodynamic Technologies w ww.epa. gov/smartway/technology/aerodynamics.htm EPA. 2011c. SmartWay Technology Program: Verified Low Rolling Resistance Tires w ww.epa.gov/smartway/technology/tires.htm EPA. 2012. Low Rolling Resis tance Tires A Glance at Clean Freight Strategies w ww.epa.gov/smartway/documents/partnership/trucks/partnership/techsheets - truck/EPA 420 - F10 - 041.pdf European Union. 1989. European Council Directive 89/297/EEC http://eur lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31989L0297:EN:HTML Evans, L . R., MacIsaac, J. D., Harris, J. R., Yates, K., Dudek, W., Holmes, J., Popio, J., Rice, D., & Salaani, M. K. 2009. NHTSA Tire Fuel Efficiency Consumer Information Program173 Development: Phase 2

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