Get on the Bus

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August/September 2003

By Jean M. Zimmerman, PT

Photos a-d. C) Use of dynamic anterior chest supports is recommended for transportation. b) Securement of wheelchair with a tie-down. c) The four securement points identified by WC19 have greatly assisted transportation staff in properly tying down wheelchairs. d) While head supports may be needed at school, during transportation only a soft cervical collar, not attached to the wheelchair, should be used.

Standards, restraint systems, and special components help students in wheelchairs get from point A to point B. When people hear that you are involved with school transportation, the first question always asked is: “Why are there no seat belts on the school buses?” The response is: the school bus seat is designed with the concept of compartmentalization.

Compartmentalization is a means of providing a cushioned environment, similar to an egg carton. The seat is designed so that the back is high. It is extremely well padded and has a certain amount of flexibility, so in the case of an accident, there is a “give” to the seat when the student comes forward into the back of the seat in front of them. Seat belts (lap belts alone) would not give the student the benefit from this feature of compartmentalization.

So whenever possible, a student who uses a wheelchair for their main means of mobility should transfer over to the school bus seat. However, many students, due to their disabilities and their need for the postural support provided by their wheelchairs, must remain in their chairs during school bus transportation.

The school bus itself is a relatively safe vehicle. Its size and yellow color make the bus obvious on the road, and it is constructed with a steel cage structure and is positioned above other vehicles.

Fig B.

Tie-Downs and Occupant Restraint Systems
A basic principle of occupant protection during transportation is to independently secure the wheelchair to the vehicle in which it is being transported. During school bus transportation, wheelchairs are secured with a four-point tie-down system. The occupant is then restrained with a three-point lap shoulder belt system. This entire system is then referred to as the wheelchair tie-down and occupant restraint system, or WTORS. These particular systems have gone through extensive design and performance requirements by the Society of Automotive Engineers (SAE). The recommended practice J2249 was adopted by SAE in January 1996, refers to the complete WTORS, and applies only to wheelchairs in the forward-facing position.

The Transit Wheelchair
Until recently, many people believed that the wheelchair was the “weak link” in the area of school bus transportation. We knew the vehicle was “safe.” We knew the WTORS had gone through testing. The questions that remained were: What about the wheelchairs themselves? Would they remain intact in the event of an accident?

The concern over this “weak link” led to years of testing by wheelchair manufacturers and safety and rehabilitation experts. This cooperative effort led to the ANSI/RESNA WC19 standard that was passed in May 2000.

Fig. A

The primary goal of the standard is to increase the likelihood that during a frontal impact, the wheelchair will remain effectively secured and the chair will then provide effective support for the occupant. A secondary goal is to make the actual securement of the wheelchair easier, more time efficient, and more error pro

The WC19 standard applies to the complete wheelchair system—namely, the base and seat. Many wheelchair manufacturers are now having their bases dynamically tested with seating systems from other companies. When being asked to provide a wheelchair that meets the WC19 standard, it is critical that the rehabilitation technology supplier (RTS) is aware of the systems that can provide this option. WC19 does include specific design and performance requirements that are particularly important in school bus transportation. A wheelchair with the transit option will have four identifiable and crash-tested securement points to which the bus staff can easily attach the tie-down straps. This standard also has requirements regarding labeling, presale literature, instruction, and warnings. The RTS must be aware that wheelchair manufacturers should be consulted regarding structural alterations.

The ANSI/RESNA WC19 standard is a voluntary standard, and does not mean that transportation can be denied to a person in a wheelchair that is not WC19 approved. However, when professionals are consulting on a wheelchair system for a child or adult, they should always alert the consumer to the availability of wheelchair systems that meet this new safety standard.

The NonTransit Wheelchair
In some cases, a transit wheelchair is not possible. Our next option is a wheelchair with an accessible metal frame to which the tie-down straps can be attached at frame junctions.

One of the biggest hurdles facing school bus transportation staff is where to tie-down the wheelchairs. Needless to say, wheelchairs have been tied down to foot-rests, armrests, and wheels through no fault of the bus staff who may not be as familiar with wheelchairs. When delivering a wheelchair, RTS should work with PTs, OTs, and transportation staff to determine the best location for the tie-downs. Plastic electrical ties in bright colors are a great way to designate where to tie down the wheelchair. Some rules of thumb when designating the tiedown locations: choose a structural securement point as high as possible but below the seat surface, and identify a welded junction of the frame or other structural areas where the frame is fastened with hardened steel bolts. The ideal angle of the tie-down straps is 45°. When working with a wheelchair that has a tilt-in-space frame, be sure to designate tie-down locations that are all on the seat frame or all on the mobility base. (Note: if a transit wheelchair has securement points on the seat frame and mobility base, follow the manufacturer’s instructions.)

The Occupant
Once the wheelchair is secured on the school bus, the occupant is restrained with a crash-tested lap and shoulder belt system. The postural supports used during positioning would not be adequate to restrain an occupant in the event of an accident. Just as our positioning belts used in the wheelchairs fit low over the pelvis, so should the lap portion of the restraint system. We need to be aware of this when wheelchairs are designed, leaving enough room so the bus lap belt portion can also run under the hip laterals.

Many times the transportation staff knows what they need to do, but we have made it impossible for them to do their job. Leaving a little space around the hip lateral or notching out a space at the bottom posterior aspect makes the bus staff’s job just a little easier, plus it assures a safer ride for the students.

Part of restraining the occupant is also through the shoulder portion of the lap-shoulder belt system. The shoulder strap should extend upward and rearward from the midpoint of the shoulder to prevent downward forces on the spine.

Wheelchair Components

Safety is always the number-one component in assessing a student’s wheelchair. However, those of us working with children who use wheelchairs know well that each child has specific positioning needs. Thus, the following components are listed as best practices to consider when prescribing a wheelchair for a child to use during school bus transportation. Remember that even if a parent is currently driving the child to school, he or she might not be doing so in 2 years so we must plan ahead.

Pelvic positioning belts: These belts definitely assist the child with their sitting posture. However, they are not effective in the case of an accident—the child will be restrained through a lap-shoulder belt system. Thus, automotive buckles are not necessary on pelvic positioning belts. Although some children with difficult positioning problems may require a Subasis bar for positioning during the day, a Subasis bar would be a problem in the case of an evacuation from a school bus. Consider the possibility of two different pelvic positioning belts with different angle pulls for these difficult positioning cases.

Headrests: During school bus transportation, the student should have a properly positioned headrest to support the head and neck. For those students who may not need a headrest during the school day, consider a removable headrest that can be used as needed. It is also critical to analyze the lateral head control to be sure the headrest is sufficient in size so that during transportation the student’s head will not be caught between the headrest and back support.

Neck collars: Remember the movements of the school bus challenge the student with limited head control. Many students will then need additional support for their heads during transportation. The recommendation for these students is to use a soft cervical collar that is not attached in any way to the wheelchair. Head straps, although effective during the day, must be removed during transportation. Rigid neck collars also should not be used. Either of these systems could cause neck injury in a crash.

Anterior chest supports: These may be used to assist with the anterior positioning of the student, but they are not crashworthy. It is the shoulder portion of the occupant restraint system that provides the ultimate protection during a crash. However, the anterior chest supports often provide the student with additional postural alignment so the occupant restraint system can be positioned correctly across the student’s body. When ordering anterior chest supports, consider ones that are dynamic so the student has some slight movement during transportation and is not held rigidly against the backrest. Since the anterior chest supports are being used for postural control, quick release buckles are acceptable. Shoulder retractors might be necessary for some students. However, these retractors will need to be easily removable prior to transportation.

Lateral trunk supports: The shoulder portion of the occupant restraint system may well be ineffective if the trunk is not properly aligned. Lateral trunk supports may be necessary to provide the trunk with proper alignment for transportation.

Upper extremity support surfaces (trays): Many children do need an upper extremity support surface during the time they are in school as a postural support. However, these support surfaces should be removed during transportation due to the potential of soft tissue damage during impact. These trays could also become a projectile in the event of a crash. There may be some unique situations in which a student must have an upper trunk support on his wheelchair during transportation. A nonflammable foam tray should be used to provide this support.

Footrests and ankle straps: The ideal situation is for the student’s feet to be totally supported and aligned. Due to deformities and spasticity, this may not be possible. The RTS should be sure to provide for protection of the feet with a system like a footbox.

Wheel locks: Wheel locks are not an essential component in stabilizing the wheelchair during transportation—this is the role of the wheelchair tie-down system. However, the wheel locks are a safety feature while the students are on the bus lift. When there is a posterior wheel lock, such as on a tilt-in-space wheelchair, consider additional side locks directly on the wheels. Often the adults assisting the student on the lift cannot reach the posterior brake.

Batteries and suction machines: Additional medical equipment must be securely fastened during transportation to prevent it from becoming a projectile in the event of a crash. This is one area in particular for which the RTS must become creative in finding a good solution to secure this equipment.

Motorized wheelchairs: The school bus industry is following the example of the airlines. It is recommended that the batteries be non-acid-type.

SUMMARY
When we think about transportation for children, we automatically think of school buses. However, the principles discussed in this article also pertain to children who ride in private vehicles such as the family van. The process of providing appropriate transportation for students is a team process. A wheelchair must be provided for a child only after consultation with the RTS, therapist, physician, parent, child, and transportation staff. Only by the entire team working together will we provide safer transportation for our students who use wheelchairs.

More information available at:

SAE J2249 Wheelchair Tiedowns and Occupant Restraints of Use in Motor Motor Vehicles. www.sae.org.
University of Michigan Transportation Research Institute. www.travelsafer.org.
Section 19 ANSI/RESNA WC/Vol 1. www.resna.org.

Jean M. Zimmerman, PT, is a pediatric PT and supervisor of occupational and physical therapy in the School District of West Palm Beach, Fla. Miriam A. Manary, senior engineering research associate for the University of Michigan Transportation Institute assisted with this article.

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