1. Transit bus injuries Incidence, biomechanics, prevention
Allan Tencer, PhD
University of Washington
Dept of Orthopedics and Sports Medicine

2. Occupant injury rates for different modes of transportation
Average no of fatalities per 100 million miles
Shaw, Gillispie, J Rehab Res and Dev, Vol. 40, No. 4, 2003, pp 309–320

3. Bus Collisions

4. Goals of the Presentation
Overview of bus injury type and incidence (limited to inside the bus)
Explain basic biomechanics approach
Describe some current research in:
frontal collisions
rollovers
wheelchair riders
non-collision injuries

5. Overall Bus Accident Statistics (National Transit database, US DOT)
Yang, Journal of Public Transportation, Vol. 10, No. 3, 2007

6. Injury and fatality rates/miles travelled (National Transit database, US DOT)
Yang, Journal of Public Transportation, Vol. 10, No. 3, 2007

7. Injury and fatality rate by impact location (National Transit database, US DOT)
Yang, Journal of Public Transportation, Vol. 10, No. 3, 2007

8. Collision factors (National Transit database, US DOT)
Yang, Journal of Public Transportation, Vol. 10, No. 3, 2007

9. Injury and fatality rate by impact location (National Transit database, US DOT)
Yang, Journal of Public Transportation, Vol. 10, No. 3, 2007

10. Summary of overall data
A significant number of fatalities (~100 fatalities, ~4300 injuries occur yearly in buses ( data)
The rate stayed constant for the ten year period ( )
Front, rear, and angled collisions produce > injury rates than sideswipes or collisions with objects
Most collisions occur in daylight, clear weather, on dry, straight roadways, with traffic signals
Studying the detailed biomechanics is a necessary next step to reducing injury rates

11. Definition of biomechanics
Biomechanics is the study of the structure and function of biological systems by means of the methods of mechanics.” Herbert Hatze, 1974
Mechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment.
Classical mechanics is based on Newton’s three laws of motion (inertia, F=Ma, action/reaction)

12. Seat design and frontal collision protection 1
Seat design and frontal collision protection 1. Roadway and bus deformation analysis
Mayrhofer, et al Paper , Conf on Enhanced Safety of Vehicles, 2005

13. 2. Modeling of the accident, assessing injuries

14. 3. Crash simulations with dummies

15. 4. Improving occupant safety
Mechanics: Torso lifts out of seat, knees hit lower part of seat ahead, head hits upper part of seat , seat ahead bends forward, occupant rebounds back into seat
Model shows how restraint use and padding of the back of the seat ahead would reduce forces on the occupant during frontal impact

16. Relevance of the research

17. Effect of restraint systems for highway transit buses in rollovers

18. 1. Structural model of bus
Güler, Paper Number , Conf on Enhanced Safety of Vehicles, 2009

19. 2. Modeling the occupants

20. Rollover model, unrestrained
Wenhui, Shengqin, 2010 Int Conf on Intelligent Computation Technology and Automation

21. Rollover model, lapbelted

22. Rollover 3 point restraints

23. Enhancing occupant safety in rollovers, lap belts and side airbag
Wenhui, Shengqin, 2010 Int Conf on Intelligent Computation Technology and Automation

24. US Wheel chair related injuries, 1991-95
WC- Injuries and Deaths Count % of Total Total no of vehicle WC Injuries , Involving Buses Involving Buses, Securement Seriously Injured Seriously Injured and Hospitalized
Shaw, Gillispie, J Rehab Res and Dev, Vol. 40, No. 4, 2003, pp 309–320

25. Wheelchair incidents aboard transit buses
Count Bus Mode When Incident Occurred
Bus turning
Sudden stop
Normal operation
Count Result/Cause
Improper securement
Passenger fell from wheelchair
Tie-down failed (“claw” type)
Tie-down failed (“strap” type)
Wheelchair failed

26. Wheelchair restraint systems (WTORS)
Restrain chair in bus and restrain occupant in chair

27. Non collision injuries in buses

28. Measured accelerations/decelerations of buses (Palacio,Non collision Injuries in urban buses)
Accelerating from a stop
Constant speed, hard braking
Accelerating from a stop, then decelerating for traffic

29. Factors affecting stability during bus motion
Grip orientation
Hand grip strength
Shoe-floor friction coefficient

30. Effect of hard braking on occupant motion
Palacio, Non collision Injuries in urban buses

31. Effect of bus accelerating on occupant motion
Loss of grip
Loss of shoe-floor contact

32. Recommendations Bus Design and Standing Occupant Location
Passengers should be discouraged from standing in the aisles. They should stand in a dedicated area opposite the stairwell and be provided with roof mounted vertical handholds.
Padding in this area is important.
Horizontal metal seat handles should be replaced with vertical ones hung from the roof of the bus.
A lower stiffness of the rubber used for the floor should be considered.

33. Recommendations Bus driver training
Driver training should include viewing of videos based on occupant simulations of non collision accident scenarios to demonstrate the influence of driving
patterns on standing occupant balance loss and subsequent injury risk.

34. Summary
Riding the bus is among the safest of transportation alternatives.
The rates of occupant injury in buses has remained about the same for many years.
External factors such as road and weather conditions, or angle of impact have little influence on injury rate.
Detailed biomechanical studies can shed light on the specific mechanisms of injury and suggest methods to reduce injury in buses.