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In support of the Federal Motor Carrier Safety Administration’s (FMCSA’s) ongoing interest in connected and automated commercial vehicles, this report summarizes analyses conducted to quantify variability in stopping distance tests conducted on commercial truck tractors. The data used were retrieved from tests performed under the controlled conditions specified for FMVSS-121 air brake system compliance testing. The report explores factors affecting the variability of the service brake stopping distance as defined by 49 CFR 571.121, S5.3.1 Stopping Distance—trucks and buses stopping distance. Variables examined in this analysis include brake type, weight, wheelbase, and tractor antilock braking system (ABS). This analysis uses existing test data collected between 2010 and 2019. Several of the examined parameters affected both tractor stopping distance and stopping distance variability.

One of the major goals in the design of the new Ford Aeromax and Louisville heavy truck product line was to achieve competitive leadership in visibility. Market research found that visibility was an important issue to the heavy truck driver. Visibility is defined as both direct and indirect (i.e., the driver's ability to see with and without the use of supplemental vision devices such as mirrors) and both interior and exterior. The scope of this paper includes the work which was accomplished in evaluating direct and indirect exterior visibility and the resulting vehicle design which achieved Ford's leadership goals. Poor weather visibility and interior vision are beyond the scope of this paper. Polar Plots were the method of choice in the Aeromax/Louisville visibility studies. Industry acceptance of these techniques has been established in the recent approval of SAE J1750, “Evaluating the Truck Driver's Viewing Environment”.

Splash and spray conditions created by tractor-trailer combinations operating on the Federal highway system have been studied and tested for many years with mixed results. Past events are reviewed briefly in this paper. In additional testing during 1983, using new state-of- the-art splash/spray suppressant devices, some encouragement was provided that these devices could work. The 1984 Motor Vehicle Manufacturers Association (MVMA) test program was designed to develop practicable and reliable test procedures to measure effectiveness of splash and spray reduction methods applied to tractor-trailer combination vehicles. Over 40 different combinations of splash/spray suppression devices on five different tractors and three van trailer types were tested. The spray-cloud densities for some 400 test runs were measured by laser transmissometers and also recorded by still photography, motion pictures, and videotape. On-site observers made subjective ratings of spray density.

The current focus in the ongoing development of autonomous driving systems (ADS) for heavy duty vehicles is that of vehicle operational safety. To this end, developers and researchers alike are working towards a complete understanding of the operating environments and conditions that autonomous vehicles are subject to during their mission. This understanding is critical to the testing and validation phases of the development of autonomous vehicles and allows for the identification of both the nominal and edge case scenarios encountered by these systems. Previous work by the authors saw the development of a comprehensive scenario generation framework to identify an operating domain specification (ODS), or external and internal conditions an autonomous driving system can expect to encounter on its mission to form critical scenario groups for autonomous vehicle testing and validating using statistical patterns, clustering, and correlation.

Solid and metallic ash particle number (PN) and particulate matter (PM) mass emission measurements were performed on a heavy-duty (HD) on-highway diesel engine and a compressed natural gas (CNG) engine. Measurements were conducted under transient engine operation that included the FTP, WHTC and RMC. Both engines were calibrated to meet CARB ultra low NOX emission target of 0.02 g/hp-hr, a 90% reduction from current emissions limit. The HD diesel engine final exhaust configuration included a number of aftertreatement sub-systems in addition to a selective catalytic reduction filter (SCRF). The stoichiometric CNG engine final configuration included a closed coupled Three Way Catalyst (ccTWC) and an under floor TWC (ufTWC). The aftertreatment systems for both engines were aged for a full useful life (FUL) of 435,000 miles, prior to emissions testing. PM mass emissions from both engines were comparable and well below the US EPA emissions standard.

We compare the simulated fuel economy and emissions for both conventional and hybrid class 8 heavy-duty diesel trucks operating over multiple urban and highway driving cycles. Both light and heavy freight loads were considered, and all simulations included full aftertreatment for NOx and particulate emissions controls. The aftertreatment components included a diesel oxidation catalyst (DOC), urea-selective catalytic NOx reduction (SCR), and a catalyzed diesel particulate filter (DPF). Our simulated hybrid powertrain was configured with a pre-transmission parallel drive, with a single electric motor between the clutch and gearbox. A conventional heavy duty (HD) truck with equivalent diesel engine and aftertreatment was also simulated for comparison. Our results indicate that hybridization can significantly increase HD fuel economy and improve emissions control in city driving. However, there is less potential benefit for HD hybrid vehicles during highway driving.

This paper summarizes initial results and findings of a model developed to determine the braking performance of commercial motor vehicles in motion regardless of brake type or gross weight. Real-world data collected by Oak Ridge National Laboratory for a U.S. Department of Energy study was used to validate the model. Expanding on previous proof-of-concept research showing the linear relationship of brake application pressure and deceleration additional parameters such as elevation were added to the model. Outputs from the model consist of coefficients calculated for every constant pressure braking event from a vehicle that can be used to calculate a deceleration and thus compute a stopping distance for a given scenario. Using brake application pressure profiles derived from the dataset, stopping distances for light and heavy loads of the same vehicle were compared for various speed and road grades.

Power Split Hybrids are unique when compared to conventional powertrains from the perspective that the engine speed is directly controlled by the motor/generator at all times. Therefore, traditional methods of detecting variations in fuel volatility do not apply for Power Split Hybrid based configurations. In their place, the Ratio-metric Fuel Compensation (RFC) method has been developed for Power Split Hybrid generator configurations to detect and compensate for engine hesitations within milliseconds of the first injection event. Furthermore, test results have shown that in the presence of low volatility fuel, RFC provides robust starts at the ideal lean air fuel ratio required for PZEV emissions compliance.

The development of a future hydrogen energy economy will require the development of several hydrogen market and industry segments including a hydrogen based commercial freight transportation ecosystem. For a sustainable freight transportation ecosystem, the supporting fueling infrastructure and the associated vehicle powertrains making use of hydrogen fuel will need to be co-established. This paper develops a long-term plan for refueling infrastructure deployment using the OR-AGENT (Optimal Regional Architecture Generation for Electrified National Transportation) tool developed at the Oak Ridge National Laboratory, which has been used to optimize the hydrogen refueling infrastructure requirements on the I-75 corridor for heavy duty (HD) fuel cell electric commercial vehicles (FCEV).

This article is a new methodology to create a strong and reliable procedure to measure oil level at dealers. Most of time, commercial trucks run full loaded. Engine oil level indication systems are designed to measure oil level at that condition. However commercial trucks are assembled and sold empty and without bodies for trucks. In result of this condition, vehicles with a false indication of low engine oil level are detected at dealers' pre-delivery inspection, resulting in oil addition. This oil addition causes unnecessary costs, since vehicles are produced with maximum oil level. The methodology presented in this study analyzes and treats all variables involved in engine oil level measurements from engine production line until dealers' pre-delivery inspection

When Ford decided to offer a midrange diesel engine family in medium trucks, it was recognized that the power-train had to be considered as a complete system in order to assure optimum compatibility. This paper describes how program objectives were established and the necessary validation programs for the truck, engine, and the chassis were conducted.

Driver is a key component in vehicle simulation. An ideal driver model simulates driving patterns a human driver may perform to negotiate road profiles. There are simulation packages having the capability to simulate driver behavior. However, it is rarely documented how they work with road profiles. This paper proposes a new truck driver model for vehicle simulation to imitate actual driving behavior in negotiating road grade and curvature. The proposed model is developed based upon Gipps' car-following model. Road grade and curvature were not considered in the original Gipps' model although it is based directly on driver behavior and expectancy for vehicles in a stream of traffic. New parameters are introduced to capture drivers' choice of desired speeds that they intend to use in order to negotiating road grade and curvature simultaneously. With the new parameters, the proposed model can emulate behaviors like uphill preparation for different truck drivers.

The pneumatic air brake system for heavy commercial trucks is composed by a large number of components, aiming its proper work and compliance with rigorous criteria of vehicular safety. One of those components, present along the whole vehicle, is the air brake tube, ducts which feed valves and reservoirs with compressed air, carrying signals for acting or releasing the brake system. In 2011, due to a lack of butadiene in a global scale, the manufacturing of these tubes was compromised; as this is an important raw material present on the polymer used so far, PA12. This article introduces the methodology of selecting, developing and validating in vehicle an alternative polymer for this application. For this purpose, acceptance criteria have been established through global material specifications, as well as bench tests and vehicular validation requirements.

During the development of a new friction material, besides the interface between lining/drum is also fundamental take in account all aspects involving the attachment of the linings on the brake shoes. This paper presents an optimization approach to the development and manufacturing parameters of brake linings, applied on medium and heavy duty commercial vehicles, aiming to assure the correct specification of the riveted joint clamp forces. These evaluations were conducted based on the quality tools documents and the theoretical aspects of the product usage as well as the modeling of key elements of the referred mechanism throughout various known applications. A calculation methodology was developed based on brake geometry, its generated forces and braking reactions required for each vehicle family.

The automotive industry has been increasingly researching and working on improving vehicle and passenger safety over the years. Following countries such as the United States and European Union, the Brazilian government has been publishing many resolutions with the objective of improving the safety of their fleet. With the publication of resolution 312 from CONTRAN (National Traffic Counsel), on April 3rd, 2009, the installation of ABS (Anti-lock Brake System) feature has become mandatory for all car and truck models to be sold in Brazil, following a staggered implementation starting on January 1st, 2010. The ABS system adds to the vehicle's current brake system, not allowing the wheels to lock during braking, which helps preserve the vehicle's stability and improve its safety, thus avoiding accidents. The technology, which is already available in a few car models, is not yet developed for the heavy trucks applications in this market.

This paper presents the benefits of following a disciplined thermal management process during the design and development of Ford Light Truck engine cooling systems. The thermal management process described has evolved through the increased use of Computer Aided Engineering (CAE) tools. The primary CAE tool used is a numerical simulation technique within the field of Computational Fluid Dynamics (CFD). The paper discusses the need to establish a heat management team, develop a heat management model, construct a three dimensional CFD model to simulate the thermal environment of the engine cooling system, and presents CFD modeling examples of Ford Light Trucks with engine driven cooling fans.

The Heavy Vehicle Propulsion Materials Program provides enabling materials technology for the U.S. DOE Office of Heavy Vehicle Technologies (OHVT). The technical agenda for the program is based on an industry assessment and the technology roadmap for the OHVT. A five-year program plan was published in 2000. Major efforts in the program are materials for diesel engine fuel systems, exhaust aftertreatment, and air handling. Additional efforts include diesel engine valve-train materials, structural components, and thermal management. Advanced materials, including high-temperature metal alloys, intermetallics, cermets, ceramics, amorphous materials, metal- and ceramic-matrix composites, and coatings, are investigated for critical engine applications. Selected technical issues and planned and ongoing projects as well as brief summaries of several technical highlights are given.

The objective of the Heavy Vehicle Propulsion Materials Program is to develop the enabling materials technology for the clean, high-efficiency diesel truck engines of the future. The development of cleaner, higher-efficiency diesel engines imposes greater mechanical, thermal, and tribological demands on materials of construction. Often the enabling technology for a new engine component is the material from which the part can be made. The Heavy Vehicle Propulsion Materials Program is a partnership between the Department of Energy (DOE), and the diesel engine companies in the United States, materials suppliers, national laboratories, and universities. A comprehensive research and development program has been developed to meet the enabling materials requirements for the diesel engines of the future.

Discussion of four factors pertinent to any overall ride evaluation. These factors are frame beaming, fifth wheel location, special body mountings, and variable loading conditions on tandem truck and tractor ride. The methodology for measuring the characteristics of these factors is reviewed and practical solutions for improved ride are given.

Ford Motor Company has introduced its dedicated Natural Gas Vehicle (NGV) trucks as mid-year 1997 offerings to complement its dedicated Crown Victoria and bi-fuel Qualified Vehicle Modifier (QVM) product line-up. The 5.4L F-250 full-size pick-up truck and the 5.4L E-250/E-350 full-size vans are production vehicles maintaining Original Equipment Manufacturer (OEM) quality and warranty while complying with all applicable corporate, federal and state requirements. Both trucks are the first OEM vehicles to certify at the Super Ultra Low Emission Vehicle (SULEV) California medium-duty vehicle standard, the Federal Ultra Low Emission Vehicle (ULEV) standard, and the Federal Inherently Low Emission Vehicle (ILEV) emission standard. The use of natural gas (NG) as a vehicle fuel required unique hardware changes in the areas of fuel storage, fuel metering, and the emission control system.