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This paper describes ongoing research conducted by the National Highway Traffic Safety Administration (NHTSA) to evaluate the potential of safety restraints on large school buses. School bus transportation is one of the safest forms of transportation in the United States. Large school buses provide protection because of their visibility, size, and weight, as compared to other types of motor vehicles. Additionally, they are required to meet minimum Federal Motor Vehicle Safety Standards (FMVSS) mandating compartmentalized seating, emergency exits, roof crush and fuel system integrity, and minimum bus body joint strength.

An extensive research program to evaluate the feasibility of improved side impact protection has been conducted by the National Highway Traffic Administration. This program concentrated on the potential reduction in thoracic injuries to vehicle occupants in side impact. Test conditions, test procedures, and test hardware for evaluating thoracic side impact protection were defined, developed, and evaluated. Injury mitigation concepts which included vehicle structural modifications and the addition of padding to the inner door surface were developed and evaluated. Test results support the feasibility of providing significant improvements in thoracic side impact protection. In addition, side impact tests were conducted on ten production automobiles. Results from these tests indicated a relatively low injury potential for occupants in some vehicles and a very high injury potential for occupants in other vehicles.

Frontal sled tests of the Part 572, APR, and Hybrid III dummies were conducted in a three-point restraint system at 50 km/hr velocity change. The tests were conducted to evaluate the dummy responses in a tightly controlled systems environment, and to compare the dummy responses to previously established cadaver responses from the same environment. The Hybrid III dummy measurement repeatability was found to be better than either the Part 572 or APR dummies, although the thoracic acceleration responses from all three are shown to be quite similar to cadavers. Correlation of the dummy measurements are made to a limited amount of both the cadaver data and accident data from the National Crash Severity Study.

IN A ONE YEAR LABORATORY STUDY, a side impact sled was designed, built, and validated. Using the sled and a newer generation of side impact dummy, a number of energy-absorbing materials were tested and superior materials identified. Initially this study concentrated on the crash test data for a number of V.W. Rabbits crashed in a previously completed study. The crashed vehicles were obtained, and interior crush tests were performed with a specially designed body form. This was done to determine how the effective stiffness (as seen by the occupant of the struck vehicle) of the interior door increases as the bullet vehicle presses against the interior door trim from the opposite side. An acceleration-type sled buck was then designed and built with an “interior door” mounted to mimic the interior stiffness determined from the crush tests. The sled was dynamically tested with a Haversine sled pulse similar to the door crash pulse.