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Individual road users face a variety of information needs that are met only in some limited way during conventional highway travel. This paper proposes the vision of a technology whose sole purpose is to improve highway travel by introducing into the system intelligent functions which deal with the limitations existing in today's “autonomous” mode of using the highway. Covered in this paper are issues that can be comprehensively addressed by Intelligent Vehicle-Highway Systems (IVHS) such as 1.) the individual driver's need for information, 2.) the individual driver's need for active assistance, 3.) communal needs for new functionality, and 4.) the whole system effects.

An open-loop limit-maneuver test methodology was refined from an earlier study which hypothesized a relationship between vehicle performance and highway safety. Refinements in methodology were attained in the areas of test apparatus, test procedure, data processing, and performance interpretation. Open-loop response measurements were conducted on a representative sample of 12 contemporary passenger vehicles. Numeric characterizations of performance are presented, indicating the range and distribution of response properties exhibited by the vehicle sample.

A mobile dynamometer has been constructed for measurement of the longitudinal force/slip characteristics of truck tires. The application of this apparatus in testing of a preliminary sample of tires has indicated that the shear force production properties of truck tires differ in many respects from the corresponding behavior of passenger car tires. These differences are discussed in terms of shear force sensitivity to a number of operating variables. The inadequacy of current semi-empirical tire models in representing truck tire traction is noted.

Certain multiply-articulated truck combinations are known to exhibit lightly damped trailer yaw motions in response to rapid inputs of steering. This paper clarifies the yaw response phenomenon and illustrates this characteristic for ten vehicle combinations which are currently in use in the U.S. The phenomenon of interest is described in terms of the “amplification” in lateral acceleration level experienced at the rear-most trailer of the combination with respect to the lateral acceleration level achieved at the truck or tractor. Results from two types of computerized simulation are presented; one representing a linear treatment of the vehicle and producing frequency response characteristics, and the other representing a rather complete nonlinear treatment of the vehicle and producing time history responses in an emergency obstacle-avoidance maneuver.

This paper provides a common data base of noise and traction properties for a sample of heavy truck tires. It provides objective information which contrasts these characteristics. It postulates that tires exhibiting improved traction performance are generally those whose tread patterns yield lower noise output. Conversely, the tire which exhibits less desirable peak longitudinal traction properties has been found to be noisier. The degree of disadvantage incurred by the bias lug-rear, bias or radial rib-front configuration cannot yet be objectified within current technology.

Intelligent Vehicle-Highway Systems (IVHS) improve the operation of cars and trucks on public roads by combining information technology with road transportation technologies. The basic ideas about IVHS are by no means new but a number of converging forces have encouraged significant IVHS development in North America recently. Based on the results of a Delphi survey to project realistic future scenarios, both applied and fundamental research agenda are being formulated in a Michigan-based IVHS program to push the IVHS technologies for advanced motorist information systems and for backup vehicle controls under emergency conditions. The scope of the research agenda includes social/human elements as well as hardware and software technological systems. The Michigan research program is expected to contribute to the development of IVHS in North America, both technically and institutionally.

The roll stability of heavy-duty trucks and truck combinations is discussed both on the level of the fundamental mechanics of vehicle response and from the viewpoint of the quantitative influence of size and weight variables. The presentation on fundamentals begins with the case of a rigidly-suspended vehicle and builds up to the case of a tractor-semitrailer with distinctive suspension stiffnesses and spring lash properties at the various axle positions. Size and weight considerations cover variations in axle load, gross weight, and overall width as well as incidental issues involving the height and possible lateral offset of the payload center of gravity. Size and weight influences on roll stability are interpreted in terms of the likely implications for rollover accident involvement.

Rollover accidents are of special concern for commercial vehicle safety. The relatively low roll stability of the commercial truck promotes rollover and contributes to the number of truck accidents and injuries. This Research Report takes an in-depth look at the mechanics and contributing factors to rollover accidents and helps to identify prevention strategies.