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This paper provides an overview of the current state of knowledge on medium and heavy truck safety and reviews the results of truck safety research sponsored by the Motor Vehicle Manufacturers Association. A number of issues have been raised about the accident experience of trucks, and the injuries and fatalities sustained by occupants. The diverse viewpoints and perceptions which exist on the reasons for these accidents and what countermeasures should be taken are reviewed. The evolutionary nature of truck accident research is presented, pointing out that sufficient detailed accident and injury data are lacking. Corresponding information on truck configuration, size, weight and exposure data remain inadequate. The role of the vehicle, driver, and highway environment in accident causation must be known and methods to achieve this goal are examined. Despite these limitations, there is progress in understanding the causes of truck accidents.

From various sources of information it is clear that truck noise is a definite public nuisance. Early noise control efforts were very productive in that many heavy duty trucks did not have mufflers, and the addition of this device made clear improvements. Further improvement requires treatment of many sources significant to the overall level. It is felt that today's “tight but attainable” 88 dBA for heavy trucks can reduce to 86 dBA by 1975 and 8k dBA by 1978 with a lot of hard work. There is promise for meaningful noise regulation in the “real world” as indicated by “calibratability” of non-standard sites.

The Vehicle Maintenance Reporting Standards of the American Trucking Associations can be used by manufacturers to improve heavy-duty vehicles. After verifying the accuracy and significance of the data the manufacturing, engineering, technical service and marketing departments can all use the information to improve vehicles and provide better service to the user.

A study to define accurately and discover new parameters of productivity for the contractor has resulted in a new design concept in off-highway trucks. This new concept has been first applied in the International Model 180 Payhauler, a rear dump vehicle of 45 ton rated capacity. The function and form criteria are discussed by components and systems in terms of the complete vehicle and on the job applications.

Prior to World War II, most heavy duty highway trucks and tractors were built as Conventionals, i. e., with the cab mounted behind the engine. In the late 1940's cab-over-engine types gained acceptance and in the 1950's the tilt cab COE was developed in its present form including sleeper cabs. The new concept is to combine the best features of conventionals and tilt cab COEs to develop a superior non-sleeper tractor that makes no compromises for sleeper cab types.

THE NEW DIESEL ENGINES developed recently by International Harvester are adaptations of existing carbureted truck engines. The manufacturing economies possible by employing existing machine tools were the governing consideration in their design. This paper discusses solutions found to the many problems presented by this approach to engine design: crankshaft, crankcase, connecting rods, pistons, lubricating system, and the like. Extensive interchangeability of parts was a result of the design concept. The engines have been successfully adapted to farm tractors, crawler tractors, stationary motors, and various automotive applications.*

The overall highway fatality rate has dropped almost contintinously since 1925, from 20 to 2.5 per hundred million miles of travel in 1984. Still, the almost 44, 000 fatalities in 1984 can, and will, be decreased. In 1983, 5, 475 of the 42, 584 highway fatalities were in accidents involving medium or heavy trucks. Only 18% of these were occupants of the trucks themselves. 82% were pedestrians or occupants of the “other vehicle.” The greatest number of combination truck accidents take place on two-lane rural roads. Single-vehicle accidents are responsible for 70% of heavy truck occupant fatalities. Doubles and heavier trucks appear to be as safe as other heavy trucks. Rollover and ejection are responsible for the greatest number of truck occupant fatalities.

The overall highway fatality rate has dropped almost continuously since 1925, from 20 to 2.5 per 100 million miles of travel in 1984. Still, the almost 44,000 fatalities in 1984 can and will be decreased. In 1983, 5,475 of the 42,584 highway fatalities were in accidents involving medium or heavy trucks. Only 18 percent of these were occupants of the trucks themselves; 82 percent were pedestrians or occupants of the other vehicle. The greatest number of combination truck accidents takes place on two-lane rural roads. Single-vehicle accidents are responsible for 70 percent of heavy truck occupant fatalities. Doubles and heavier trucks appear to be as safe as other heavy trucks. Rollover and ejection are responsible for the greatest number of truck occupant fatalities. When asked about her top priority as the new Secretary of Transportation, Mrs. Dole replied, “There's no higher mandate for the Department than to promote safety….”

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.