Transportation Injuries
On this page
Direct answer
Pedestrians struck by motor vehicles accumulate injuries in sequence — primary bumper-height leg fractures, secondary bonnet and windscreen injuries as the body is thrown, and tertiary road-impact or run-over injuries with patterned tyre marks; in child pedestrians the Waddell triad combines leg fracture, trunk injury and contralateral head injury. Occupants suffer deceleration injuries: aortic laceration at the isthmus, steering-column chest trauma, Chance fractures from lap seat belts, and whiplash cervical strain in rear-end collisions. Drunken driving is separately criminal under section 185 of the Motor Vehicles Act, with a statutory blood alcohol limit of 30 mg per 100 mL, and the 2019 amendment sharply raised the fines.
What you must remember
- Pedestrian sequence: bumper-height leg injuries indicate the vehicle's front geometry (adult tibia and femur around mid-leg, higher in larger vehicles); bonnet and windscreen injuries follow; ground impact and run-over tread marks complete it.
- Waddell triad: in child pedestrians — femur fracture, abdominal or thoracic injury, and head injury on the opposite side from being flung across the bonnet.
- Whiplash: rear-end collision hyperextends then flexes the neck, classically straining the mid-cervical segments with delayed neck pain and ligamentous injury.
- Seat belt injury pair: the diagonal strap fractures ribs and clavicle with cardiac contusion, while the lap belt produces the seat belt sign — a transverse abdominal bruise — with Chance (flexion-distraction) fractures of the lumbar spine and hollow viscus injury.
- Airbag injuries: abrasive facial and forearm lesions, thermal and alkali keratitis from the propellant chemistry, and upper limb fractures when arms ride the deploying bag.
- Deceleration signature: thoracic aortic laceration just distal to the left subclavian artery (isthmus) from traction; also liver lacerations of the right lobe and mesenteric tears.
- Two-wheeler reality: helmets prevent the base-of-skull and vault fractures that dominate Indian rider deaths; the pillion rider, unhelmeted in practice, carries the worse head injury pattern.
- Legal anchor (MV Act 185): driving with blood alcohol at or above 30 mg% or under the influence of drugs is an offence — first offence up to six months' imprisonment and fine (raised substantially by the 2019 amendment), roughly doubling on repeat; section 184 covers dangerous driving.
Reconstructing a night-time hit-and-run
An adult pedestrian is brought dead; the vehicle has fled. The autopsy becomes a measuring exercise. Bruising and comminuted fracture of the right tibia at about 50 cm above the heel indicate bumper contact, and the height suggests a car rather than a lorry. A patterned, intradermal abrasion with periodic ridges over the left shoulder and back mirrors a tyre tread — a run-over event; the corresponding ribs are stamped-fractured. A left temporal contrecoup haemorrhage matches a fall backwards onto the road. Paint transfer and embedded glass spicules are recovered with adhesive film, and clothing retained for the laboratory. Internally, the aorta shows an incomplete laceration at the isthmus — the deceleration injury proving the body was in motion. The board concludes: pedestrian struck from the right, thrown down, run over — cause of death head injury, giving the police the vehicle geometry to hunt and the charges to frame under the MV Act and the rash-negligence homicide provision (IPC 304A, now BNS 106 with its aggravated hit-and-run clause).
Where the exam probes
The favourite diagram question is driver versus front passenger: the driver takes steering-column chest and aortic injuries, the unrestrained passenger goes through the windscreen — evert the scalp and match the glass fragments. Examiners ask why the seat belt sign matters clinically: the bruise flags concealed lumbar and bowel injury, demanding observation rather than discharge. On railway deaths, coupling injuries between buffers and a segmented body are distinguished from post-mortem severance by vital reaction at the cut ends. And the viva staple on alcohol: the 30 mg% statutory limit under section 185, with 80 mg% belonging to the classical intoxication tables — quoting both in context separates a well-taught candidate from a memorising one.
Frequently asked questions
What is the Waddell triad in a child pedestrian?
Femur fracture from bumper impact, abdominal or thoracic injury from bonnet contact, and contralateral head injury from the fall — the classic three-phase pattern.
What injuries does a lap seat belt cause?
A transverse seat belt sign across the abdomen with Chance flexion-distraction fractures of the lumbar spine and blunt bowel or mesenteric injury.
Why does the aorta tear at the isthmus in crashes?
The freely mobile arch and the tethered descending segment move at different speeds during deceleration, shearing the wall just distal to the left subclavian artery.
What is the legal blood alcohol limit for driving in India?
Thirty milligrams per 100 millilitres of blood under section 185 of the Motor Vehicles Act, with fines sharply increased by the 2019 amendment.
How are run-over injuries identified at autopsy?
Patterned intradermal abrasions matching tyre tread, stamp fractures of underlying ribs and soft-tissue crushing between tyre and road surface.