The impact on economic activity may produce losses that exceed any additional tax revenue gains. This study compared telephone interviews and roadside observations of vehicle occupancies. Vehicle occupancy ratios have declined from the 1.89 recorded in 1977. Increases in safety expenditures do seem to result in lower fatality rates. More research is needed to determine which safety expenditures produce the best results.
School buses are already very safe.
Other safety investments can provide more safety per dollar of expenditure. Awareness of potential tort liability needs to be a factor in highway design decisions. The best strategy is to thoroughly document the rationale for design decisions. This survey of state practices found that immaturity was the key element in young driver accident rates. Restrictions on minor's driving privileges generally have withstood legal challenge.