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The relatively fragile nature of racing tires, coupled with the inevitable track debris which results from racing accidents, ensures that racing drivers will routinely experience conditions involving flat tire vehicle dynamics. We define flat tire vehicle dynamics as a situation which requires the driver to provide steering and/or braking and acceleration control while the vehicle is running on one or more tires which have dramatically reduced tire pressure. In the present work, we simulate the handling and braking vehicle dynamics which occur in the presence of a single flat tire on the vehicle. The flat tire was simulated via drastically reduced cornering stiffness, partially reduced limiting frictional capability and increased rolling resistance, and was alternatively simulated on both the front and rear axle. No simulations were conducted with more than a single flat tire because multiple tire failures which do not involve an actual accident contact and/or damage are rare.

During the month of May, 1994, there were a total of 15 accidents at the Indianapolis Motor Speedway (IMS). Of this total, six accidents occurred during practice and/or Qualifications Attempts and nine occurred during the 78th running of the Indianapolis 500-Mile Race. All six practice accidents were analyzed through the use of videography, skidmark measurements, photographs, angle of wall impact (if a wall impact occurred), vehicle damage and yaw angle measurements. The accidents were categorized according to type and severity, mechanical failure or driver error, speed at the initiation of the accident sequence, driver injury (if injuries occurred), weather, track and traffic conditions. Race accidents were also analyzed. The study represents the continuation of a long-term program to catalog, analyze and reconstruct accidents at IMS.

Open-wheel dirt-track racing represents one of the most dangerous forms of motor racing. The potential for touching and/or interlocking of rotating wheels, combined with the frangible and rutted nature of the track surface itself, makes the occurrence of x-axis [8] rollovers routine. In addition, the rollovers themselves are usually at a high enough speed so that very violent dynamics and occupant accelerations occur. The accelerative vectors present an unusual set of challenges to the restraint systems employed. In this work, we examine a single dirt-track rollover event.