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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.

Development of a seat with an active adjustable seatback stiffness for enhanced safety during a rear impact is demonstrated. Review of literature suggests that there is not a single value for seatback stiffness to optimize occupant protection. An automobile seat whose stiffness can be actively adjusted based on EDR input and other factors can potentially enhance occupant safety during some rear impact crashes. Static pull tests were performed using a prototype seat demonstrating how seatback stiffness can be modified, and deformation limited, using electromechanical means. Research and development of this technology is ongoing.

The concept of a seat with an active adjustable seatback stiffness for enhanced safety during a rear impact was published previously. Static testing of a demonstrative prototype is supplemented with repeated dynamic tests at various velocity / acceleration levels. These tests were performed with a Hybrid III Anthropomorphic Test Device (ATD) and demonstrate that the occupant response can be modified by engagement of the device based on the severity of the crash pulse and other factors. A mathematical model for the dynamic response of the seat and the correlated occupant response is in development. Refinement of this technology is complemented by results of the dynamic testing.

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.

Snowmobile acceleration, braking and cornering performance data are not well developed for use in accident reconstruction. Linear acceleration and braking data published by D'Addario[1] gives results for testing on 4 snowmobiles of various make and model. This paper presents the results of on-snow tests performed in 2014 which include acceleration and cornering maneuvers that have not been published previously. Maximum and average cornering speeds and corresponding lateral accelerations are presented for turns of radius 20, 35 and 65 feet (6.1, 10.7 and 19.8 meters) on level, packed snow. Performance values for acceleration, braking, and cornering are determined in tests with and without a passenger. Results of linear acceleration and braking tests were found to be comparable to the previously published work. The data are useful in snowmobile accident reconstruction for certain types of snowmobile motion analyses.