4 Goals of the Presentation Overview of bus injury type and incidence (limited to inside the bus)Explain basic biomechanics approachDescribe some current research in:frontal collisionsrolloverswheelchair ridersnon-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 objectsMost collisions occur in daylight, clear weather, on dry, straight roadways, with traffic signalsStudying 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, 1974Mechanics 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 analysisMayrhofer, et al Paper , Conf on Enhanced Safety of Vehicles, 2005
13 2. Modeling of the accident, assessing injuries
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 seatModel shows how restraint use and padding of the back of the seat ahead would reduce forces on the occupant during frontal impact
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 HospitalizedShaw, 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 OccurredBus turningSudden stopNormal operationCount Result/CauseImproper securementPassenger fell from wheelchairTie-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
28 Measured accelerations/decelerations of buses (Palacio,Non collision Injuries in urban buses) Accelerating from a stopConstant speed, hard brakingAccelerating from a stop, then decelerating for traffic
29 Factors affecting stability during bus motion Grip orientationHand grip strengthShoe-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 gripLoss 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 drivingpatterns on standing occupant balance loss and subsequent injury risk.
34 SummaryRiding 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.
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