The very high speeds achieved by IndyCars at the 1992 Indianapolis 500-Mile Race and practice have led to a complete reconsideration of the safety implications involved in the sport. The present work describes calculations performed in order to totally redesign and reconstruct the outer concrete retaining wall and fence structure at Indianapolis Motor Speedway (IMS), to ensure spectator safety. Car capabilities were first examined to ascertain energies involved in realisticcollisions with the wall at racing speeds. A series of practice and race accidents was examined via frame-by-frame video analysis, and further calculations performed to refine energy calculations.Calculations and actual accident analyses indicate that a substantial amount of kinetic energy is lost before car-to-wall impact can occur through aerodynamic drag and tire scrub. Wall strength requirements and estimates of impact forrealistic car speeds, spectator visibility and construction were also computed. The requirements for potential NASCAR - style racing and/or a possible Formula One event at IMS were evaluated, and competition in these categories of racing was considered during the above calculations. Finally, an overview of the current car safety requirements and practice viz a viz racing within concrete barriers was developed.