New research comparing fatal crashes of all bus types nationwide found that, while there are statistically more deaths tied to school bus-related crashes, there are more of those vehicles on the road, and school bus drivers are the safest.

The Center for National Truck and Bus Statistics at the University of Michigan Transportation Research Institute (UMTRI) utilized FMCSA general research funds to study 293 total fatal crashes involving all types of buses in 2008. Utilizing statistics from the Buses Involved in Fatal Accidents (BIFA) file compiled by UMTRI, of crashes identified in NHTSA's annual Fatality Analysis Reporting System (FARS), the researchers compared school buses, transit buses, intercity buses, charter buses and miscellaneous "other" buses that include those operated by private companies, churches, non-profit organizations, departments of corrections, and private groups like sports teams and entertainers.

School buses were the most common operator type of vehicle studied at more than 39 percent of the total pool. The number of school buses involved in fatal crashes rose 7.5 percent to 120 in 2008 from 111 the year prior, and school buses accounted for 40 percent of all fatalities. About 50 percent of the fatal bus crashes occurred from 6 a.m. to 8:59 a.m., or from 2 p.m. to 4:59 p.m., primarily involving school buses due to the hours school is in session.

In comparison, transit buses were involved in 86 fatal crashes while intercity buses were involved in nine fatal crashes, charter 27, "other" 41 and "unknown" 10.

But, Daniel Blower, the director of the Center for National Truck and Bus Statistics at (UMTRI), said it should not be assumed that the greater amount of school bus crashes mean that school buses are less safe than other types of buses. In fact, he said the opposite is true as the school bus fatality figures are an "artifact of exposure."

Blower said the data file gives the most accurate identification of bus types involved in fatal crashes. But, he explained, the data doesn't by itself reflect the safety of a given operation. In reality, the rate of vehicles involved in fatal crashes is a combination of risk and exposure.

"The fact that the school bus type is more frequent along with transit buses I think largely reflects that there are probably more of those out on the road operating," he said, adding that school buses are also utilized by many different organizations in many situations, not just school districts operating home-to-school routes.

According to the American Public Transportation Association 2011 Fact Book, transit buses accounted for more than 5.4 million unlinked passenger trips in 2009. Meanwhile, the school bus industry estimates that each year school buses alone account for more than 10 billion passenger trips, including regular route service as well as activity trips.

The UMTRI study found that about half of the fatal crashes involving school buses were presumably not the fault of the bus driver, as the school bus is most often the struck vehicle. Twenty-five fatal crashes were caused when another vehicle crossed a center divider into on-coming traffic and struck the school bus head on. Another 11 fatal crashes resulted from another motorist rear-ending the school bus, or a so-called "under-ride" event, and nine fatal crashes occurred when another vehicle sideswiped the school bus in its own lane.

"You see that it's overwhelmingly the other vehicle [that] is coming into the school bus' lane," Blower said.

Blower added that researchers were also completing an updated school bus under-ride study for NHTSA, which was expected to be released later this year.

School bus fatal crashes were recorded in 36 states, with the most incidents (14) occurring in Florida. California, Texas, Illinois, Ohio, Georgia and New York each recorded six to nine fatal crashes. The remaining states all had less than five school bus-related crashes that resulted in fatalities.

But despite the approximately 480,000 school buses on the road each school day engaged in student transportation service, only 13 school bus passengers were killed on-board the bus, as were three school bus drivers. Researchers found that 103 school buses were involved in fatal crashes, as were seven "small" school buses. Also involved in fatal crashes were one "small special needs bus" and five "special needs" school buses, both types of vehicles being defined as school buses with wheelchair lifts and tie downs.

Blower pointed out that it remains challenging to determine exactly on what kind of service the school bus was providing as police reports and other interviews with bus operators don't always indicate the difference between a normal school route or an activity or extracurricular trip.

"There's the classic yellow school bus, but those vehicles can be used in all different kinds of situations," Blower explained. "Counties might use them to transport prisoners. Companies might use them to transport their own employees, and sometimes they get converted for personal use."

The most recently produced NHTSA FARS database of school bus fatalities and injuries for the 2007-2008 school year showed six school bus passenger deaths, on par with the nationwide average each year. No report was prepared for the 2008-2009 school year.

In comparison, the study found that charter and "other" buses had the most passenger fatalities, 31 and 30, respectively. The balance of fatalities were about an even split between transit (five passengers) and intercity (six passengers) buses. Of non-motorist fatalities, a total of 120 occurred as a result of a crash with a school bus, 92 of which occurred in the other vehicle. Meanwhile, another 21 pedestrians and seven bicyclists or riders of a "personal conveyance" were killed in school bus-related crashes.

The study also determined operator type in all 293 crashes. As far as driver-related factors are concerned, an underlying cause could not be determined in nearly 71 percent of fatal crashes involving school buses. Failure to yield right away came in a distance second at almost 12 percent of the crashes.

School bus drivers also appear to be among the safest. Of the 120 school bus drivers involved in fatal crashes, 91 had zero previous accidents and 15 drivers had one previous crash on their record. Nearly 91 percent of the school bus drivers, or 109 out of 120, had no previous moving convictions. This rate was better than transit drivers (85 percent), intercity drivers (78 percent), charter drivers (76 percent), drivers of "unknown" buses (60 percent).

"School bus operators tend to have among the best prior driver records and among the lowest probabilities of having committed a driving error that contributed to the crash," Blower said.

School bus drivers (96.7 percent) and transit drivers (96.5 percent) were statistically even in the percentage of those who had no previous suspensions that occurred within three years of the recorded fatal crash. The exact same number of school bus drivers had zero speeding convictions within the same time period compared to 90.7 percent of transit drivers.

Interestingly, the research team, which included Anne Matteson, Linda Jarossi and John Woodroofe, also determined that 88 of the 120 fatal school bus crashes involved public school district buses, compared to 27 school buses owned or operated by private school bus contractors.

UMTRI has produced the BIFA file each year since 1999.