After Earnhardt 's death , NASCAR began Process_start an intensive focus on safety that has seen Perception_active the organization mandate the use Using of head-and-neck restraints , oversee the installation of SAFER barriers at oval tracks , set Placing rigorous new inspection rules for seats and seat-belts , develop Coming_to_be a roof-hatch escape Escaping system , and the Car of Tomorrow—which eventually led to Causation the development of a next-generation race car built with extra driver safety in mind .