| In the late 1960s, a series of seat belt tests were conducted at the University of California Loa Angeles. Studies of data from this test along with subsequent test data raised questions about the potential for serious injury with safety belt use because the bone structure in the abdominal and pelvic areas of the majority of school children is still in a developmental stage.
A later University of California study concluded that the concept of compartmentalization - scientifically spacing the seats a certain distance apart, raising the height of the seat backs, and padding the seats to reduce the severity and incidence if injury in a collision - would be more cost effective than installing seat belts.
In 1978 NHTSA conducted a series of sled tests which showed that lap belts caused an increase in peak accelerations, which resulted in harder impacts with seat backs.
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