Driver fatigue was a reported factor in fewer than one motorcoach accident every 21/2 years, reported the University of Michigan Transportation Research Institute (UMTRI). Drowsiness, sleep or fatigue was noted as contributing factors for five bus drivers out of a total of 1,483 buses, including transit and school, involved in fatal accidents from 1995 to 1999. The report, an analysis of federally collected commercial vehicle accident data, also found that motorcoaches account for a small percentage (11%) of total fatal bus accidents. Forty percent involve school buses and 36% involve transit buses. While fatal accidents involving transit buses are distributed evenly throughout the week, UMTRI reported that those involving motorcoaches occur more often on the weekends.