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In reconstruction of on-roadway vehicle accidents, tire-road surface friction coefficient, mu (μ), can be estimated using a variety of available data. Common ranges and values for μ are used in calculations forming the foundation for most accident reconstruction techniques. When the roadway surface is gouged or disrupted by vehicle components, accounting of dissipated energy can be successful where supporting force data exists. Roadway gouge forces can vary widely depending upon such factors as road surface construction, surface temperature, and the velocity and geometry of the gouging mechanism. Such dissipated energy can be significant in accounting of total reconstruction energy. This paper presents experiments aimed at quantifying gouge force by controlled pavement gouging tests.

The relatively rare occurrence of injury or fatality in fuel-fed fires has received considerable attention in automotive safety rulemaking and products liability litigation. The literature related to fatalities associated with fire is confirmed by recent FARS data, and there are no reliable field data which confirm a need for further injury-reducing effect related to FMVSS 301. NHTSA has acknowledged this by removing crash fire rulemaking from its priorities plan. The police-reported crash fire data now available must be supplemented with in-depth investigation by trained teams before informed judgements can be made regarding further safety improvements with respect to crash fire injury.

A vehicle trajectory simulation called VTS has been developed as an aid for reconstruction of automobile accidents. The two dimensional vehicle has longitudinal, lateral and yaw degrees of freedom, a point mass at the center of gravity) yaw inertia about the center of gravity and four contact points (“tires”) which can be arbitrarily positioned. No collision or aerodynamic forces are modeled. The traction surface is represented as a flat plane with a specified nominal friction coefficient. Several quadrilateral “patches” may be applied to the surface to change the friction coefficient in specific regions. User vehicle control consists of timewise tables for steering angle and traction coefficient for each of the four wheels. When used individually or in conjunction with other computer modules, VTS provides a convenient, accurate modular tool for trajectory simulation.

The CRASH3 computer program, a well known and useful tool in accident reconstruction, is shown to be innaccurate by comparison with car-to-car crash test data. Claims for accuracy of about 10 percent cannot be validated. Both the impact model and the damage only model yield results which are in error. Cases involving error well in excess of 20 percent are demonstrated. These inaccuracies are due primarily to the omission of terms in the formulation of the energy equation and to the sensitivity of the solution to the input estimate of principle-direction-of-force.

An economical alternative technique is presented for obtaining vehicle frontal crush characteristics from a series of repeated low speed barrier crashes. Results were analyzed using a technique of linear correlation of residual crush depth with a defined crush energy parameter. The data compared closely with crashes reported in the literature, and suggested that the structure exhibits only a slight strain rate sensitivity. Crush energy is shown to correlate well with dynamic crush depth. Relations among dynamic and residual crush and recovery distance are reported, Velocity restitution is shown to be about constant at 15% over the impact velocity range employed. A force-deflection relation based on the offset force linear harmonic oscillator theory is suggested, shown to agree quite well with data. Repeated crash testing can be an effective method to obtain information needed for development of analytical and predictive tools useful in design and reconstruction.

CRASH3 plays an important role in the development of accident data files, and in addition it is often used for reconstructing specific accidents. Had it been intended from the outset for this latter purpose, its development may have progressed along slightly different lines. It is now appropriate to examine the use of CRASH3 in specific accidents, the use of available crash test data, and the nature of the likely CRASH3 user. Suitably accounted for, all these factors would have a significant influence on the design of accident reconstruction algorithms, including any contemplated revisions of CRASH3. Such considerations are the subject of this paper.

Published data relevant to snowmobile crash reconstruction is comparatively limited, especially pertaining to mountain snowmobiling and riding in deep snow. Snowmobiling is a unique motorsport activity as it requires substantial rider input and physical interaction to properly control the vehicle. The added complexities of varying slope angle and snow depth in mountain terrain make application of test data from testing done on flat surfaces less useful when applied to sloped terrain analysis. New data from testing performed in deep snow conditions on various slopes is presented in this paper. Acceleration tests were performed using two late model mountain snowmobiles from a stop on various slope angles. Additional related factors such as snow density, trenching, and snow mass momentum exchange are also discussed. Comparison of these test results to previously published snowmobile testing data advances the understanding of snowmobile acceleration parameters into mountain terrain.

Gouges and scratches to rollover protection structures are informative to the reconstruction and analysis of real-world vehicle rollover crashes. Variations in ground surface composition can be correlated with accompanying witness marks on the vehicle rollover protection structure. This paper presents the results of rollover protection structure specimen tests using a variety of test speeds and surface compositions. The test results and analyses that follow are displayed for use in comparison to similar damage on subject crash vehicles. In addition, impact of steel rollover protection structures with various opposing ground surface materials can produce visible sparks in low light conditions. Tests were performed to show the ability of these structures to produce sparks from various surface impacts.