RTA Flashcards
Vehicle crash energy
Energy=(mph^2 ×0.034)/(stopping distance)
Contributory factors to accidents
Road - bend, leaves, visual obstruction Enviromental Mechanical failure Human error - speed - fatigue - inattention Intoxication - alcohol and drugs Natural disease - collapse at wheel
Pedestrian injuries
Height of vehicle vs centre of gravity
- child vs adult
- car vs van vs lorry
Primary injuries
- bumper strikes legs
- height above heel important - if breaking nose lowers, if accelerating nose raises
Secondary injuries
- bonnet strikes thigh, pelvis and chest
- windscreen and pillars strikes chest and head
Tertiary injuries
- victim thrown onto road surface, roadside objects or other vehicles
Running over
- patterned imprint abrasion from tyres, underneath of vehicle
- flaying lacerations
- oil/dirt staining of skin
Signs of speed of impact
Road markings
Throw distance
Impact at 30mph = 80% survival rate
Impact at 40 mph = 80% fatality rate
Pedestrian injury patterns
Wrap around
- bumper strikes leg below centre of gravity
- throw distance suggests speed of impact if vehicle braking hard
Forward projection
- struck at or above centre of gravity -> thrown forwards and down
- risk of running over
- adult struck by high fronted vehicle
- child struck by car
Wing top
- struck by front wing
- carried over wing and falls off to side
Roof top
- high speed
- secondary impact with roof of vehicle
Somersault
- very high speed
- thrown high into air - no secondary impact with vehicle
- tertiary impact with road
Primary impact bumper injury
Car bumper strikes upper tibia of adult or femur of child
Usually height is 40-50cm
- lower if car breaking
- higher if car accelerating
Height of abrasion above heel + shoe
Tibial fracture
- wedge fracture at point of impact from angulation
- spiral impact at weakest point from rotation impact
Types of car impact
Head on with another vehicle Head on with stationary object Rear impact Side impact Side-swipe Roll over Post crash fire
Features of frontal impact
Occupants move towards point of impact
- knees strike parcel shelf or dashboard
- bracing injuries to legs and drivers arms
- shoe soles marked by pedals
Continue upwards and forwards
- head strikes windscreen, roof or A pillar
- chest strikes steering wheel or dashboard
Forces to car occupants
Deceleration Whiplash Dashboard and parcel shelf Steering wheel and pedals Windscreen and pillars Seat belt injuries Intrusion Ejection
Safety measures in cars
Crumple zones and side impact bars
- absorb impact energy
Seatbelts
- restrain body during deceleration
- spread area of deceleration force and duration of impact due to stretching
- reduce impact with steering wheel and dashboard
- prevent ejection during rollover
- seatbelt injuries seen on neck, chest and abdomen
Airbags
- restrain upper torso during deceleration
- spread area of deceleration force and duration of impact
- reduce impact with steering wheel, dashboard and car interior
- airbag injuries - module cover, neck hyperextension, bag-slap
Car occupant injuries
Scattered abrasions, bruises and lacerations
Head and neck
- skull fracture, brain injuries, diffuse traumatic axonal injury (DTAI)
- cervical spine #
Chest
- rib and sternal #
- contusion and laceration to heart and lungs
- transection of aorta
- haemothorax rapidly fatal
Abdomen
- lacerated liver, spleen, kidney, bowel, diaphragm
- pelvic #
Legs
- pelvic or femoral #
Factors to help identify driver
Denial by disqualification or intoxicated driver
Injuries can be matched to vehicle interior
- diagonal seatbelt injuries
- dicing injuries from tempered side window glass
Transference of trace material
- blood, hair, tissue on windscreen, dash, seatbelt or airbag
- clothing fibres
Shoe impressions
Vehicular suicide features
Physical - single vehicle impact - stationary object - seatbelt not worn - no sign of avoidance - intoxication Psychological - hx of depression - previous RTA - substance abuse - precipitating event - recent erratic driving - trial
Motor cyclist injuries
High speed Unstable Unprotected Primary leg injuries Secondary injuries - head and neck - chest - heart and lung lacerations, rib #, haemothorax - abdomen - limbs Tertiary injures from road, other vehicles
