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This article presents the results of an analysis of the yaw marks left by a car with normal pressure in all tires and then normal pressure in three tires and zero in one rear tire. The analysis is a continuation of research on influence of reduced tire pressure on car lateral dynamics in a passing maneuver, discussed in the SAE paper No. 2014-01-0466. Preliminary analysis of yaw marks has shown, that a wheel with zero pressure deposits a yaw mark whose geometry differs from the yaw mark made by a wheel with normal pressure based on which we could calculate: critical speed, slip angle and longitudinal wheel slip. The aim of the presented research was to analyze the yaw marks left by car with zero pressure in one rear wheel in order to check the possibility of determining the vehicle critical speed, slip angle and longitudinal wheel slip. It was reached by performing bench and road tests during which the vehicle motion parameters were recorded using GPS Data Logging System.

The objective of the paper is to present the results of an investigation of the effect of reduced tire pressure on car lateral dynamics in lane change maneuver. The intended aim was attained by performing bench and road tests. The aim of the bench tests was parameterization of the mathematical model of the tested car. The road tests covered the vehicle motion with reduced and no tire pressure on a curvilinear track adequate for bypassing an unexpected appearing obstacle. Next, simulations in PC-Crash were performed, and the results were compared with those obtained in experiments.

Critical Speed Formula (CSF) belongs to the canon of tools used in reconstruction of vehicle accidents. It is used to calculate vehicle speed at the beginning of tire yaw marks and, together with the entire methodology of processing the information contained in the marks into the data, is often referred to as the Critical Speed Method (CSM). Its great practical importance as well as recurring doubts as to the reliability make it one of the best experimentally and theoretically studied methods. Although the CSF applies in fact to a point mass, it is used with reference to a vehicle, i.e., an increasingly complicated multi-body system. Accident reconstruction experts point out the particular usefulness of Lambourn's research concerning the CSM in respect to a passenger car.

The objective of the paper is to present the results of verification of ABS models applied in PC-Crash and HVE (Human-Vehicle-Environment) computer programs in various road conditions. The aim was reached by comparison of the road tests results obtained and calculations performed using the programs for the same initial values of the measured variables. First static tests were carried out for parameterization of the mathematical model of the object of the research - a passenger car equipped with ABS. Road tests were performed including extreme braking on a μ-split with and without corrective steer, and extreme braking during lane-change maneuver.

One of the stages of designing of the steered wheel multi-link suspension system is a multidimensional synthesis related to the parametrization of its mechanism, complying with imposed constructional and kinematic restrictions. The restrictions referring to the structural configuration of the suspension mechanism in the system related to the car body follow the dimensional analysis of the body, driving system, brake system, steering system, springy and damping elements. The paper presents a method of determining the locations of the joints connecting the car body with links of the designed suspension system, realizing the kinematic characteristics of camber and steering angles of the wheel, with the assumed accuracy to the required characteristics, complying with certain restrictions.

The problem of uncertainty is particularly important in the analysis of accidents involving pedestrians because even slight but simultaneous modifications of many data can result in shifting the responsibility line. Calculations include a number of irreproducible parameters whose numerical values are either selected from literature (e.g. reaction time, lag time, friction coefficient) or on the basis of verbal description (e.g.: “…when he was still running along the sidewalk, it was obvious he was going to rush into the roadway”, “the car wasn't braking too hard”). Additional difficulty is caused by performing mathematical analyses of different versions given by the witnesses (e.g.: “he was walking slowly”, “he was walking at a fast pace”), which together with other uncertain data lead to a large number of additional “subversions”. In the paper an analysis of the sensitivity of function describing the kinematics of a pedestrian accident has been made.

A method of synthesis of rear wheels multi-link suspension of one degree of freedom has been proposed. Using virtual mechanism the characteristics of wheel orientation and wheel centre position were defined. Following the motion simulation tests and having found the vehicle with the selected rear suspension characteristics to meet the required criteria a synthesis of five-link suspension was performed. The trajectories of the centres of joints coupling were determined, objective functions formulated and the parameters of suspension mechanism were initially determined. Next tapering functions in respect of camber and toe angles characteristics were adopted, and the co-ordinates of centres of the joint couplings determined again. A set of design parameters for five-link suspension mechanism was created.

In road accident analysis the problem of uncertainty of calculation results becomes essential particularly when modification of input values within the adopted ranges leads to diametric change of the answer to the question posed by the court of justice (e.g. “collision from the right-hand side of the center line” – “collision from the left-hand side of the center line”, or “the accident could have been avoided” – “the accident could not be avoided”). The aim of the paper was to present a method of collision reconstruction calculation using the principle of conservation of momentum, the principle of energy conservation, and the principle of kinetic energy and work equivalence (energy balance) (Marquard), taking into consideration Monte Carlo simulation method. The applicability of the method in determination of distribution function for vehicle collision velocities was proved and, what is more important, its practical uselessness in determination of collision location.

The article presents problems in determining intensive braking parameters from the tachograph chart recordings. A number of braking trials were recorded by a tachograph and a decelerometer simultaneously. Next a comparative analysis of the recordings was performed using both the Siemens VDO method and by electronic processing with commonly available equipment. The first method proved to have limited possibilities for interpretation of the recordings for quantitative determination of intensive braking parameters. The second proved unreliable (with the existing scanner resolution). It has been shown that it is not possible to determine unequivocally the braking time, and consequently the deceleration reached.

In the paper SMASH - a computer program for road accident simulation is presented. Besides the logic of the program the models of vehicle, tire and crash itself are analyzed briefly. Data and diagrams showing the comparison between SMASH results and actual tests data are presented.