Abstract
It is hypothesized that the effectiveness of mandatory approaches are partially or wholly offset by changes in behavior of drivers who take greater risks, thus maintaining the same level of overall risk as before. Results of a study of driver behavior before and after seat belt use law did not support this hypothesis. There was no evidence of risk compensation among drivers in their travel speeds, following headways, turning headways, or responses to yellow signals. In a second, linger- term study, drivers were found to travel significantly slower around sharp curves eight to nine months after a belt use law became effective than one year earlier.