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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.

This study is to explore the application of electrorheology (ER) to the real-time control of damping forces that are transmitted through the nose landing gear for an F-106B aircraft. The main part of the landing gear is a strut that consists of a pneumatic spring and an ER controlled damper that is situated on the strut centerline and applies a force directly opposing the vertical displacement of the nose wheel. The damping element rotates in response to strut displacement, employing a co-axial arrangement of stator and rotor plates connected to the opposing electrodes in the control circuit. The vertical displacement is converted into rotation of the damper through a screw-nut mechanism. The ER fluid between the electrodes is thus engaged in shear along circumferential lines of action. This design results in a fast time response and a high ratio of strut forces achieved under ER- vs. zero-field control. Compact size and simplicity in fabrication are also attained.

The Metropolitan Transportation Center (MTC) is an operational unit of the Michigan Department of Transportation (MDOT). The MTC is the focal point of Michigan's leadership role in the Intelligent Vehicle-Highway Systems (IVHS) technology. The MTC serves as a traffic operations service center and an IVHS test facility. The MTC facility now under construction and the functions to be performed within the MTC will be described. The infrastructure being developed to expand the existing traffic management in the Detroit Metropolitan area and the testbed program will be described. Specific emphasis will be placed on describing the first project of the testbed in which both the public and private sectors will be able to participate in the evaluation of various surveillance technologies and in-car communications. Initial efforts will address the “low end” users community by testing multiple incident detection and management techniques.

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.

In spite of significant forces pushing for an accelerated development of Intelligent Vehicle-Highway Systems (IVHS) in the United States, no formal national program in IVHS is emerging rapidly. It appears that a number of policy issues, both at the macro and at the micro levels, both domestic and international, need to be resolved before IVHS can be put into place in America. The way in which these issues are to be resolved will probably have significant impacts on both the automotive industry and the infrastructure that supports automotive transportation around the world.

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.

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.

This paper provides a method whereby vehicle stopping performance can be specified, measured, and compared independently of the test surface. The method provides for an independent measure of the prevailing friction potential of the test surface which is used to normalize the measured stopping performance of the test vehicle. The concept presented is tailored toward a safety argument and toward rulemaking as a potential adaptation to braking effectiveness requirements which currently exist. A new mobile tire dynamometer, developed for this program, is discussed, as are the results of a demonstration test program.

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.

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.