March 2004
ISS-Instructional Course
Transportation Safety for
Wheelchair Occupants
Linda van Roosmalen, PhD
Douglas Hobson, PhD
Department of Rehabilitation Science and Technology
University of Pittsburgh
Funding: National Institute on Disability and Rehabilitation
Research
Application to practice
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Wheelchair transit and associated risks
Methods to prevent occupant injury
Safety guidelines and Standards
Resources
Wheelchair Transportation Safety
• 1.6 million wheelchair users
• Access to motor-vehicle transportation is the
key to functioning in society
• ADA prohibits discrimination in public
transportation services
• 2001 New Freedom initiative calls for
integration of disabled persons into workforce
and community - “transportation” critical factor
in meeting this priority
• 82% of wheelchair users indicate difficulty with
using public transportation
• Wheelchair users have 10% higher
unemployment rate
Impact Severity
• Injury Risk:
– Proportional to velocity change
– “Loading = velocity * body weight”
• Occupant Restraints protect by:
– Prevent occupant ejection from vehicle
– Prevent excessive occupant motion
– Reduce occupant loading
– Increasing time of energy exposure
Safety Guidelines
1. Secure the wheelchair
2. Restrain the occupant
3. Remove loose accessories from
wheelchair
4. Remove parts that can injure occupant
during an impact
– Lap trays, loose objects, postural supports,
communication devices, neck rings
Sled Impact Testing
Frontal
30mph
20g
Safety System #1
• Secure the Wheelchair to the Vehicle
Wheelchair Securement Systems
– Four point strap type tie-downs
– Docking systems
– Other: wheel-clamps, hybrids
– Rearward facing compartments (in large
buses)
Strap type tie-down system
• Advantages
– Four securement
points (improves
crash response and
stability)
– Adaptable to most
wheelchair types
– No additional
wheelchair hardware
required
– Withstands crash
forces
IMMI-Westfield (IN)
Strap type tie-down system
• Disadvantages
– Invasion of personal space
– Lengthy securement times
– Requires operator/attendant for securement
– Tiedowns easily misplaced or soiled
– Lack of defined wheelchair securement
points
– Requires operator training when securing a
variety of wheelchairs
Easy Accessible Securement
Points
NO!!!
Easy Accessible Securement
Points
YES!!!
Docking Systems
• Advantages
– Quick securement
times
– Independent
securement
– Eliminates need for
human judgment of
securement point
location
– Minimizes error
– Withstands crash
forces
EZ-Lock (Baton Rouge, LA)
Docking Systems
• Disadvantages
– Requires add-on hardware
– Requires adaptations to all wheelchair
types
– Hardware adds weight and length
– Hardware affects ground clearance
– Fewer securement points (less stability
and control of crash response)
Wheel Clamps
Wheel Clamps
• Disadvantages
– Unable to safely withstand crash forces
– Not compatible with all wheel types
– Requires attendant for securement
• Advantages
– Fairly quick securement
– Less invasive
Passive Restraint:
Containment
Wheelchair is
positioned rearward
facing in the vehicle
Passive Restraint:
Containment
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Easy to use
Quick
Non-constraining
Independent use
HOWEVER….
• For use in ’low-g’ vehicles
only
– More research is needed to
evaluate safety during
emergency driving
situations
(Van Hool, Belgium)
Safety System #2
• Restrain the Occupant
– To vehicle and/or wheelchair
Lap belts mounted to wheelchair frames are
generally for positioning purposes and NOT for
safety during transit!!!
Occupant Restraints
Reduce Risk of Injury
• Prevent occupant ejection
• Increasing time over which the
occupant comes to a stop
– Decreasing deceleration or “G-loads”
– Higher weight means higher loads!
• Decrease occupant forward travel
– Reduce risk of occupant impact with
vehicle interior
Sled Impact Testing
without use of Occupant Restraints
Frontal
30mph
20g
Sled Impact Testing
with proper Occupant Restraints
Frontal
30mph
20g
3-Point Occupant Restraint
Upper torso belt
(shoulder belt)
Pelvic belt
(lap belt)
Harness Type Restraint
EZ-On Vest
Gorilla Car Seat
Snug Seat Car Bed
Carrie Bus Seat
Occupant Restraint Safety
• Improperly positioned pelvic belt:
– Abdominal injury due to ‘submarining’
– Lumbar vertebra injury in frontal crashes
• Improperly positioned shoulder belt:
– Excessive head excursions
– Secondary impact with vehicle surfaces
– Injuries to vital thoracic cavity organs
Adomeit & Heger, 1975; Leung et al., 1985
Occupant Restraint Problems
• Appropriate belt fit related to:
– Shoulder belt anchor point
– Pelvic belt anchor point
– Wheelchair and occupant size
– Location of wheelchair in securement
zone
– Available clearance for belt placement
Common Problems
• Shoulder belt slip off user’s shoulder
– Due to shallow angle of torso belt
• Shoulder belt rubs against user’s neck
– Discomfort,
– Resistance to using belt
– Decreased upper torso restraint
• Anchoring upper torso restraint below
shoulder may result in downward
loading of torso and spine
Occupant Restraint
“Best Practices”
• Use both pelvic and shoulder belt to restrain
the occupant
• Lead restraints over bony anatomy
– Shoulder restraint over the Sternum
– Pelvic restraint over the (pelvis) Iliac Crests
• Avoid loading soft tissues (abdomen)
• Remove belt slack
• Use a retractor to reduce upper torso belt
slack
• Restraint pre-tensioner reduces belt loading
Wheel clamps
Sideward facing position
4-Point Tiedown Systems
Twisted Belts
Belt interferes with tires
Occupant Restraints
& Postural Supports
• No use of shoulder belts
•Pelvic belt over armrests
Ongoing Research
• Automated Wheelchair Securement
– Universal docking
• Customized Occupant Restraints
– Wheelchair integrated
– Consumer friendly
Safety System #3
• Support the Occupant
– Wheelchair seating system
– Wheelchair frame
– Wheelchair components