A Position Paper of the
National Association of State Directors
of Pupil Transportation Services

August 3, 1998

No one questions that school buses are the single safest form of highway travel, or that today's school buses provide students with exceptional levels of safety. Despite these facts, the school transportation industry constantly is seeking ways to make an already safe form of transportation even safer. In this quest, there are times when individuals and organizations will disagree over the potential benefits of certain safety features. This paper provides a discussion of the current status of passenger crash protection in large school buses and suggests areas of potential change to current Federal requirements if it is determined that there is a need to further increase the safety of school buses.

The issue of whether to require seat belts on large school buses [those with a gross vehicle weight rating over 10,000 pounds] is a topic that has been studied thoroughly and debated for many years. An important, but often overlooked fact in the debate, is the difference between seat belts (lap belts only) and safety belts (lap/shoulder belts). In general, advocates for lap belts point out the potential benefits of lap belts in terms of reduced injuries and fatalities in certain types of school bus crashes -- typically side impact and rollover crashes. They also refer to improvements in pupil behavior as the result of lap belt usage. Finally, advocates point to the importance of consistency in teaching children to buckle-up in all types of motor vehicles -- if there are no lap belts in school buses, advocates believe there is an obvious break in the chain of consistency.

Those opposed to the installation of lap belts on school buses point to a wide variety of data and facts: (1) the safety record of school buses; (2) analyses of all types of real-world school bus crashes; (3) laboratory crash test data; and (4) the effects of lap belts on children without sufficiently developed bone structure.

It is important to realize that lap belts only provide restraint around the hips of a seated individual. Lap/shoulder belts, on the other hand, provide restraint around the hips and across the upper torso of a seated individual. The potential safety benefits of these two systems are very different. Lap belts, even when properly positioned and tightened, still allow full upper torso movement which can result in head contact with surrounding surfaces at higher impact velocities than if the person was unbelted. Lap/shoulder belts restrain the upper torso and, thereby, reduce the likelihood of head contact with a surrounding surface.

Safety Record of School Buses
One of the major reasons for the outstanding safety record of school buses is the manner in which they are constructed. As is the case with all motor vehicles sold in the United States, school buses have to meet a stringent series of Federal motor vehicle safety standards designed to provide school bus passengers with high levels of safety should a crash occur. One of those Federal standards, "School Bus Passenger Seating and Crash Protection," establishes minimum occupant crash protection requirements for school buses built after April 1, 1977. For large school buses, the Federal standard requires occupant protection through a concept called "compartmentalization" -- strong, well-padded, well-anchored, high-backed, evenly-spaced seats. The effectiveness of "compartmentalization" has been confirmed in independent studies by the National Transportation Safety Board and the National Academy of Sciences.

National Transportation Safety Board (Safety Board)
In 1987, the Safety Board completed detailed analyses of 43 serious accidents involving large school buses to evaluate the effectiveness of "compartmentalization." ¹ These crashes included frontal and side impacts, and included a large number of rollover crashes. A Safety Board team of accident investigators reconstructed each crash, evaluated the motion of the occupants, and identified the cause(s) of the injuries/fatalities. For each crash, an evaluation was made of whether the use of lap belts would have made a difference in the injury levels of the school bus occupants.

From a public policy perspective, the Safety Board's conclusions are extremely important.

• School bus occupant deaths and the serious or worse injuries sustained by survivors were, for the most part, attributable to the occupants' seating position being in direct line with the crash forces.

   

• It is unlikely that the availability of any type of restraint would have improved their injury outcome.

   

• Lap belt use probably would have made no change in the total number of school bus passengers who died in the crashes investigated ... possibly one more death would have resulted.

   

• Lap belt use probably would have made no change in the number of surviving school bus passengers with severe or worse injuries.

   

• At best, lap belt use probably would have reduced somewhat the injuries of less than 8 of the 24 surviving school bus passengers with serious injuries. At worst, seat belts might have increased the injury to almost as many passengers with serious injuries as it improved.

   

• Lap belt use probably would have worsened the outcome for one-fifth [20%] of the 58 school bus passengers with moderate injuries.

These real-world data clearly show that while lap belts may offer a safety benefit in some instances, in most crashes the installation and use of lap belts would not have changed the injury outcome of the crash. Equally important is the fact that in a significant number of crashes the use of lap belts would have worsened the injury levels. In fact, it appears that in one instance the use of lap belts would have killed a child that would have otherwise survived.

Since this study was completed in 1987, there have been a number of school bus crashes that have resulted in fatalities and serious injuries. While each of these crashes and the consequences are tragic, it is important to study such crashes to identify areas for potential safety improvements. Three of the most tragic crashes occurred in Carrollton, Kentucky; Alton, Texas; and Fox River Grove, Illinois.

In Carrollton, 27 occupants of a former school bus died due to fire and smoke inhalation. In Alton, 21 students drowned in a bus that rolled on its side and was totally submerged in water. And, in Fox River Grove, 7 students were killed when their bus was struck by a speeding train. Each of these crashes required immediate, quick action by passengers under extreme conditions, in order to survive. In Carrollton, a gasoline-fed fire spread rapidly through the bus, and provided very little time for evacuation of the crowded bus. In the Alton crash, the Safety Board's investigation report notes that there "was inadequate time for 81 desperate students to escape through the available window openings and rear emergency door. ... Escape was further complicated by dark murky water which obscured vision. ... The 21 students who perished did not have enough time to escape from the bus." In Fox River Grove, the students sitting in the back of the bus saw the train approaching and had only fractions of a second to move from the back of the bus to the front.

In each of these crashes, unlatching of lap belts would have required additional time under panic conditions. In Carrollton, the passengers, many of whom were sleeping, were first stunned by a crash with a pickup truck at a speed of over 100 miles per hour, and then had to cope with fire and dense smoke in an effort to escape the burning bus. No one died from trauma-induced injuries. In Alton, the bus was struck by a tractor-trailer, then plunged off a cliff into water, and the students had to escape in murky water while the bus was on its side. Any passengers on the right side of the bus would have been hanging from the seats by the lap belts. Again, no one died as a result of trauma-induced injuries. In Fox River Grove, all of the students in the back of the bus had only milliseconds to get out of their seats and run forward.

There is little doubt that the installation and use of lap belts in these crashes would have resulted in additional fatalities and serious injuries. This "fact" must be considered in any debate over the benefits of lap belts in school buses. Unfortunately, these crashes often are ignored by those who advocate the installation of lap belts on school buses. Instead, advocates for lap belts in school buses tend to base their beliefs on only a few crashes. As stated earlier, there have been school bus crashes where lap belts may have offered a safety benefit. However, when the entire range of school bus crashes are considered, there is no compelling body of data to support the installation and use of lap belts in large school buses.

National Academy of Sciences
In 1989, the National Academy of Sciences completed a study at the direction of the United States Congress on "the principal causes of fatalities and injuries to school children riding in school buses and of the use of seat [lap] belts in school buses and other measures that may improve the safety of school bus transportation." The Academy was directed to "determine those safety measures that are most effective in protecting the safety of school children while boarding, leaving, and riding in school buses." In its conclusions, the Academy noted that "the overall potential benefits of requiring safety [lap] belts on large school buses are insufficient to justify a Federal requirement for mandatory installation. Funds used to purchase and maintain seat [lap] belts might be better spent on other school bus safety programs and devices that could save more lives and reduce more injuries." The Academy pointed out that since children are at greater risk of being killed in the school bus loading zone (i.e., while boarding or leaving the bus) than as a passenger on the school bus, "a larger share of the school bus safety effort should be directed to improving the safety of school bus loading zones." ²

One of the often cited conclusions from the Academy's study is that "seat (lap) belts, when properly used on post-1977 ... school buses, may reduce the likelihood of death or injury to passengers involved in school bus crashes by up to 20 percent." That estimate was based on a 1986 study of rear seat occupants in passenger cars, only a small minority of which were of school age. Based on the differences in the sizes of school bus and passenger car occupants and the importance of proper position and adjustment of lap belts, it is not clear that this 20 percent effectiveness estimate is accurate with respect to school buses. Also, the greatest benefit of lap belts to rear seat occupants of passenger cars was in terms of preventing ejection from the car. Fatalities and serious injuries due to ejection from a school bus are rare.

Another important issue has been raised by the medical community. Small childrens' bone structure, particularly their hips, is still developing through grade school. Accordingly, lap belts can cause internal injuries to children. As noted in a December 1997 article published by the American Academy of Pediatrics, "[T]he anterior iliac crests, the anchor points for the adult seat [lap] belt, are not adequately developed in children younger than 10 years of age to function in this capacity. Therefore, the belt is neither well-positioned nor secure." Appendix A presents an excerpt from the article that appeared in the December 1997 issue of Pediatrics in Review.

In addition to the potential for a lap belt to cause internal injuries to small children, lap-belted school bus passengers also risk more severe head and neck injuries in crashes. Unlike passenger cars where there may be a significant amount of space between the rear seat and the front seat, in school buses the seats are designed to be close. In 1985, Transport Canada issued a report on a series of crash tests it had conducted that indicated lap-belted test dummies in school buses received more severe head and neck injuries than unbelted test dummies in severe frontal crashes. At the time, several individuals questioned the test procedures and results of the Transport Canada study. However, no additional testing was done. In a 1997 series of crash tests conducted by the National Highway Traffic Safety Administration, the same results were found - lap-belted test dummies in school bus seats received higher head injury measures than unbelted test dummies. These 1997 tests appear to confirm the earlier study by Transport Canada.

At the 1998 National Conference on Highway Safety Priorities, a presentation was made that graphically showed lap belt-related injuries to children and adults. The presentation pointed out what is common knowledge among safety professionals - 3-point lap/shoulder belt systems are superior forms of occupant crash protection. The state of California recognized this fact by requiring the following language on a label affixed to all used vehicles that are offered for sale and that are equipped with lap belts only:

"WARNING: While use of all seat belts reduces the chance of ejection, failure to install and use shoulder harnesses with lap belts can result in serious or fatal injuries in some crashes. Lap-only belts increase the chance of head and neck injuries by allowing the upper torso to move unrestrained in a crash and increase the chance of spinal column and abdominal injuries by concentrating excessive force on the lower torso. Because children carry a disproportionate amount of body weight above the waist, they are more likely to sustain those injuries."

School Bus Crash Configuration
Nationwide, the National Safety Council estimates that more than 20,000 crashes occur each year in which a school bus is involved. Most of these crashes are minor in nature, however, serious school bus crashes do occur. When a serious crash occurs, the school bus passengers are mostly uninjured or receive minor to moderate injuries. ³ These serious crashes involve frontal, angular, side, rear, and rollover crashes.

Unfortunately, there are crashes that result in serious injuries or fatalities to school bus passengers. Most of these crashes are very severe, and as reported by the National Transportation Safety Board:

"schoolbus occupant deaths and the serious or worse injuries ... were, for the most part, attributable to the occupant's seating position being in direct line with the crash forces. It is unlikely that the availability of any type of restraint [emphasis added] would have improved their injury outcome."

With respect to minor and moderate injuries, as discussed earlier, the Safety Board's study found that lap belt use would have worsened the injury levels for 20 percent of the students receiving moderate injuries. It was not possible to judge the effect of lap belt use on those passengers that only received minor injuries.

Obviously, there are some school bus crashes where lap belts may have reduced or eliminated injuries and/or fatalities. As was done in the National Transportation Safety Board's 1987 study, it is possible to assess what injuries may have been mitigated because of lap belts. However, it is much more difficult to suggest what injuries may have occurred as the result of the use of a lap belt, and whether those injuries would have been more severe than the injuries that were mitigated.

In order to evaluate objectively the potential safety benefit of any device, all aspects of the device must be studied and understood. It is not legitimate to consider isolated or anecdotal information and ignore a larger body of information and knowledge. Similarly, it is not legitimate to rely on hypothetical and theoretical information when real-world information exists.

Other Organizations
There is unanimity among a wide range of national organizations ⁴ that are charged with establishing national motor vehicle and highway safety policy, or are respected organizations within the safety community, that "compartmentalization" is effective in school buses and that lap belts should not be required in school buses. However, as with any controversial issue, there are organizations that believe there should be lap belts on school buses. These include a number of medical associations and state-level organizations. These organizations express their support for lap belts in school buses, but generally provide no data or analyses to justify their position or do not consider all of the real-world data discussed above.

For example, in May 1996 the American Academy of Pediatrics (AAP) issued a policy statement, "School Bus Safety," that makes recommendations to enhance community systems for addressing school bus safety education, awareness, and practices. The policy statement makes recommendations on a wide range of school transportation topics, e.g., school bus inspections, brake retarder systems, and adult supervision of children crossing streets. No data or analyses are presented or discussed to support these recommendations. With respect to its recommendation in favor of "the installation of seat [lap] belts on all newly purchased school buses," the only data referenced by AAP is the conclusion from the National Academy of Sciences' study that the use of lap belts on large school buses may reduce the likelihood of death or injury to passengers by 20 percent, with an assumption that lap belt use rates are 50 percent. ⁵ No other data or analyses are cited, and no attempt is made to address the extensive amount of real-world data that show lap belts would not always be beneficial in school bus crashes.

Some organizations and individuals have mis-characterized the conclusions from the National Academy of Sciences' report discussed earlier. In that report, the Academy concluded "seat (lap) belts, when properly used on post-1977, Type I school buses, may reduce the likelihood of death or injury to passengers involved in school bus crashes by up to 20 percent." [Emphasis added]

According to a March 27, 1998, Florida Senate Staff Analysis and Economic Impact Statement, the Florida PTA utilized the National Academy of Sciences report to assert "that seat [lap] belts on school buses would improve safety by 20 percent." [Emphasis added] Similarly, a citizens' group in Minnesota, People Advocating Seatbelt Safety, also claimed that "50% usage would reduce deaths and injuries by 20%." [Emphasis added]

There is a significant difference between the National Academy of Sciences' conclusion that says "may" and "by up to" and Florida PTA's and Minnesota's claim of "would." This is particularly important since the data used by the National Academy of Sciences were based on adults in the back seat of passenger automobiles, not children in school buses, as discussed earlier.

Lap Belt Requirements in New York and New Jersey
Currently, there are two states that require the installation of lap belts in large school buses. New York has required the installation on all new school buses purchased after June 30, 1987. However, New York does not have a law requiring students to use the lap belts. Such requirements are left up to the individual school districts. Recent information indicates that 44 (6 percent) of New York's 709 public school districts have adopted policies which require all students to wear the available lap belts. New Jersey passed a law in 1992 requiring the installation and use of lap belts in all new large school buses.

The National Transportation Safety Board attempted to conduct a study of the effectiveness of lap belts in school buses in New York and New Jersey several years ago, however, the study has not generated any useable information since (thankfully) there have not been any serious crashes of school buses equipped with lap belts. As a result, there is no body of real-world data involving serious school bus crashes that supports the position that lap belts provide additional levels of crash safety in the aggregate over the safety provided by "compartmentalization."

Potential Changes to School Bus Passenger Crash Protection
While the State Directors Association believes that "compartmentalization" is a highly-effective means of providing passenger crash protection in large school buses, and that there are no aggregate data to support the need for lap belts in large school buses, the Association recognizes that it may be appropriate to consider ways of making school buses even safer. Based on real-world crash data and the medical communities' knowledge of the problems associated with ill-fitting lap belts on young, school-aged children, the State Directors Association maintains its belief that lap belts are not a reasonable alternative to, or supplement to, "compartmentalization."

The State Directors Association believes that if there were any proposed changes to Federal requirements regarding passenger crash protection in large school buses, those changes must be based on thorough and defendable research. Such research should include laboratory crash testing that represents the type of real-world crashes that have resulted in serious injuries and fatalities to school bus passengers, and should develop data on the relative performance of various means of crash protection. Based on these laboratory test data, informed decisions could be made about whether "compartmentalization" continues to be the most appropriate means of providing crash protection to school bus passengers, and if not, what means of crash protection are better, and why.

The association believes it is appropriate for the National Highway Traffic Safety Administration to study the adequacy of current passenger crash protection in school buses, and to conduct an extensive research program to determine if there is a more effective means of providing crash protection to students on school buses. Such a study would be consistent with the requirements of Section 2007 of the Transportation Equity Act for the 21st Century, which "authorizes the Secretary [of Transportation] to conduct a study to assess occupant safety in school buses."

In the course of this research, it is imperative that the effect of each potential crash protection system on school bus evacuation times be considered. Additionally, if an "active" passenger restraint system is considered, then the safety effects on students that choose not to utilize the restraint system must be considered in the overall evaluation. Finally, the effect of other Federal safety standards must be included in any assessment of passenger crash protection.

As stated earlier, the State Directors Association believes that the current "compartmentalization" requirements provide excellent levels of safety to school bus passengers considering all the types of crashes involving school buses. However, if alternatives to the current requirements are found to be necessary, the State Directors Association believes the two most logical options to consider in any research program on the subject of passenger crash protection in large school buses are: (1) lap/shoulder belts for all designated seating positions; and (2) upgrades to "compartmentalization."

Lap/Shoulder Belts
As stated earlier, there is unanimity within the motor vehicle safety community that lap/shoulder belts offer superior levels of occupant crash protection than lap belts only. At the current time, there is little, if any, information available on the technological feasibility, operational practicability, potential benefits, and other potential positive and negative concerns associated with the installation of lap/shoulder belts in school buses. The State Directors Association believes it is important to develop as much information as possible on lap/shoulder belts in school buses. This includes identifying engineering problems associated with installing lap/shoulder belts in school buses, given the Federal requirements for "compartmentalization," and whether some of those Federal requirements would have to be eliminated or modified. It also includes information on the potential safety benefits to both restrained and unrestrained school bus passengers, who may not have the benefits of "compartmentalization," since it is unrealistic to expect all passengers would wear the lap/shoulder belts, and wear them correctly.

Upgraded Compartmentalization
Unlike lap/shoulder belt systems which require school bus passengers to buckle up, "compartmentalization" is a passive passenger protection system. It may be possible to make school buses even safer through improvements in padding at seating locations. The State Directors Association would support any research initiatives directed at upgrading "compartmentalization" in large school buses.

Conclusions
School buses are the safest form of motor vehicle travel in the United States. While every serious injury or fatality to a student on a school bus is tragic, such instances are very few in number each year. Nationwide, on average there are fewer than 10 school bus passenger fatalities each year out of approximately 10 billion student trips. Based on all of the real-world facts, "compartmentalization" in today's school buses is providing an extremely high level of crash protection to student passengers. There are no statistical data to suggest that a safety problem exists in large school buses that the installation of lap belts would solve. As a result, the State Directors Association continues to support the conclusions reached by the National Academy of Sciences and the National Transportation Safety Board, and the position of the National Highway Traffic Safety Administration, that there is no supportable need for lap belts on large school buses.

Recognizing that a few state and local governments have established requirements for lap belts on large school buses, the State Directors Association believes that it important to consider the recommendations provided by the National Academy of Sciences - "states and local school districts that require seat belts on school buses must ensure not only that all bus passengers wear the belts, but that they wear them correctly." As noted in the American Academy of Pediatrics article in Appendix A, "behavioral characteristics of the child, such as the inability to sit still and perfectly erect for a sustained period of time, often result in the child either maneuvering out of the system or altering the fit." Also, because of the lack of bone structure in children younger than 10 years of age, "the [lap] belt is neither well-positioned or secure." These child developmental concerns must be considered by states and local school districts that require lap belts on school buses.

The National Association of State Directors of Pupil Transportation Services believes that legislators and regulators have a responsibility to establish public policy through laws and regulations. In carrying out that responsibility, the Association believes that legislators and regulators have an obligation to make decisions based on data and science, not emotion and supposition. To do otherwise could result in public policies that improperly use society's limited resources, and could result in additional injuries and fatalities, rather than fewer injuries and fatalities. Accordingly, the Association believes it is reasonable and appropriate for the National Highway Traffic Safety Administration to conduct a research program that not only develops current information on the effectiveness of "compartmentalization" in providing safe transportation to students in school buses, but also evaluates other forms of school bus passenger crash protection. If at the conclusion of this research the data supports changes to Federal safety requirements for school buses, the State Directors Association believes new safety standards should be proposed based on all available data and science.

As a final note, the school transportation industry is made up of thousands of people who have the safety of children as their highest priority. Most are parents, also. Whenever there are devices or procedures which have the potential to make school transportation even safer, the State Directors Association is at the forefront of the debate. If a device or procedure proves to be beneficial based on all available data and information, the State Directors Association stands ready to provide its support to legislators and regulators.

© 1998 National Association of State Directors of Pupil Transportation Services. All rights reserved.

Issued: July 1998

Footnotes

1) "Crashworthiness of Large Poststandard Schoolbuses," National Transportation Safety Board, Report Number NTSB/SS-87/01, March 18, 1987. This study was designed to evaluate the effectiveness of the Federal requirements for "compartmentalization" under FMVSS No. 222. As such, it only compared the post-1977 school buses with pre-1977 school buses that were built to Federal requirements. Since there were no Federal requirements for lap belts on either pre-1977 school buses or post-1977 school buses, it would have been inappropriate to include any crashes involving large school buses equipped with lap-belts in this study.

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2) It should be noted that while improvements have been made in school bus loading zone safety since the National Academy of Sciences' 1989 report, the greatest safety risk to students is still as a pedestrian in the school bus loading zone. Three times as many students are killed as pedestrians compared to passengers on school buses.

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3) According to mid-1980's state crash data reviewed by the National Academy of Sciences, only 5 percent of school bus passenger injuries are incapacitating (e.g., severe lacerations, broken limbs, head/chest injuries). A 1997 study of state crash data by NHTSA showed only 4 percent of school bus passenger injuries were serious, severe, or critical.

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4) These organizations include: National Highway Traffic Safety Administration, National Transportation Safety Board, National Safety Council, National Academy of Science/Transportation Research Board, National Association for Pupil Transportation, National School Transportation Association, and others.

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5) As discussed earlier, the 20 percent effectiveness estimate was based on a study of rear-seat occupants in passenger cars. Based on the differences in the sizes of school bus and passenger car occupants and the importance of proper position and adjustment of lap belts, it is not clear that this 20 percent effectiveness estimate is accurate with respect to school buses.

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Appendix A

"Safe vehicle packaging" for the infant and child requires occupant protection systems that are based on child anatomy and development rather than on adult anatomy. Adult belt systems simply do not provide optimal protection for children. Restraints for children must be adjustable to accommodate the changing dimensions and behavioral characteristics that occur with growth and development.

Salient features of child development relevant for occupant protection include rapid changes in weight, height, and body proportions. Infants and young children have a disproportionately large head size, high center of gravity, relatively poor head support because of weaker neck structures, soft pliable bones of the skull that are less protective of the intracranial contents, and cartilaginous cervical vertebrae that are being replaced slowly by bone. Skeletal and facial injuries can disrupt growth plates, resulting in subsequent abnormal growth.

The abdominal organs, liver, spleen, and kidneys are less protected by the rib cage compared with the adult, and the bladder is less protected by the bony pelvis, thereby making these organs susceptible to injury in a crash. The anterior iliac crests, the anchor points for the adult seat [lap] belt, are not adequately developed in children younger than 10 years of age to function in this capacity. Therefore, the [lap] belt is neither well-positioned nor secure.

The ratio of sitting height to total height decreases with growth. The curvature of the vertebral spine and the tilt of the pelvis result in children not sitting upright, so adult seat [lap] belts that are designed for upright posture do not fit well. Posture changes with growth, allowing the child to assume an erect posture. However, behavioral characteristics of the child, such as the inability to sit still and perfectly erect for a sustained period of time, often result in the child either maneuvering out of the system or altering the fit.

Adult [lap] belts tend to ride up over the abdomen and place the load directly on the abdomen. The child is at risk for flexing over the belt in a crash and for the pelvis to "submarine" under the belt. The seat belt syndrome, a spinal fracture (usually lumbar or sacral) associated with an internal abdominal injury, is related to compression of internal abdominal organs and hyperflexion of the spine over the belt system.

Lap/shoulder belts may be similarly problematic. The cervical seat belt syndrome, fractures or fracture-subluxations of the proximal cervical spine with or without head injuries, may result from hyperflexion of the neck over a secured torso. The buckle of the lap/shoulder belt may sit high against the child's abdomen and slide up during a collision, thereby increasing the chance of submarining under the belt. The shoulder portion of the belt does not sit on the shoulder, rather often lying against the child's neck, and frequently is placed behind the child or under the arm, disrupting the optimal function of the integral restraint system.

Child restraint systems must be designed to distribute forces over a large portion of the body, protect the organs not well-protected by bony skeletal structures, and account for both the sitting posture of the child and the inability of the iliac crests to serve as anchor points for the belt system. These systems must be practically "childproof" in terms of maintaining proper fit, given both the anatomic and behavioral characteristics of children.