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Rollovers & Seatbelts

Rollovers & Seatbelts. What is a “ROLLOVER”?. What is a “ROLLOVER”? a single vehicle incident vehicle “rolls” 90 deg or more “driver looses control”. Does PDO have many “ROLLOVERS”?. Rollovers. PDO: many rollovers every year!. Rollover !!. 19-Oct-2007: on the way to Bahja

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Rollovers & Seatbelts

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  1. Rollovers & Seatbelts

  2. What is a “ROLLOVER”?

  3. What is a “ROLLOVER”? • a single vehicle incident • vehicle “rolls” 90 deg or more • “driver looses control”

  4. Does PDO have many “ROLLOVERS”?

  5. Rollovers PDO: many rollovers every year!

  6. Rollover !! 19-Oct-2007: on the way to Bahja Driver:         seatbelt – minor injury Passenger: Seatbelt – minor injury Passenger:  NO seatbelt - DEAD

  7. 9-Sept-2007: on the way to Haima Driver:         NO seatbelt - DEAD Passenger: NO seatbelt - DEAD Passenger: Seatbelt – minor injury Rollover !!

  8. Rollover !! 2-Aug-2007: Qarn Alam Driver died – no seatbelt – head crushed under vehicle

  9. 23-Oct-2006Marmul-Thumrait 7 km before Harweel junction Driver: 39 yrs old, died Speed: at least 140 km/hr PDO Spec vehicle: tampered! Seatbelt did not help anymore Rollover !!

  10. 150 km/hr March/2001 Maqbool & Faisal Died Rollover !! Tyreblew Anything that goes wrong at high SPEED is a BIG problem!!

  11. Straight blacktop Fahud-Nahada Veered off to the rightOvercorrected, rolled 4xClassic S patternNO rollover bar 30/Oct/01 LTI Permanent Total Disability Rollover !!

  12. 20/Nov/01 Fatality & LTI Blacktop road Fahud- Nizwa Rollover !! Car moved right at high speed. Driver over corrected and got into an S pattern:Rolled & Flipped.

  13. 2 man came out alive. They were wearing their seatbelts. 1 man DIED. He was NOT wearing his seatbeltNO Seatbelt= DEATH Nimr to Muscat 13th June 98

  14. What would you “prefer”? a Rollover or a Head on Collision

  15. Rollovers are killers! Video 1 Video 2 No of accidents No of death

  16. Common features of rollovers: • Speed (80 km/hr can be too fast !!) • Mostly 4 WD (high Centre of Gravity cars) • Most on straight roads • Most classic “S” curves • Many on blacktop roads at high speed • Few: tyre blow-out, junction/speed

  17. Why does a vehicle roll ? How many rolls will it do ? Simply Physics ! Understand the physics to understand the controls……

  18. We have a “vehicle at speed”: why does it roll? Centre of Gravity M = mass (kg) v = speed (m/s) g = gravitational acceleration Gravity Force GF = M x g (= constant)

  19. Why does it roll?.... Because of centrifugal force! Centre of Gravity M = mass (kg) v = speed (m/s) r = turn radius (m) g = gravitational acceleration Mv2CF= ------- r Centrifugal Force (CF) Gravity Force GF = M x g (= constant)

  20. Why does it roll?.... Because of centrifugal force! Centre of Gravity M = mass (kg) v = speed (m/s) r = turn radius (m) g = gravitational acceleration Mv2CF= ------- r Centrifugal Force (CF) CF increases with:- v higher (higher speed)- r smaller (sharper turn) Gravity Force GF = M x g (= constant)

  21. We have a “rolling vehicle at speed” How many rolls will it do ?

  22. We have a “rolling vehicle at speed” How many rolls will it do ? Kinetic Energy: ½ Mv2 This energy is dissipated during the rolls More energy more rolls! Energy goes up with the square of the speed! M = mass (kg) v = speed (m/s)

  23. Next 4 slides: • 2 RTA’s are shown • they are almost the same • compare them • see what the differences are • discuss why the outcome was different

  24. 25/2/2003 14/3/2003 140 km/hr 80 km/hr 2 Black Top Roads2 Cars driving

  25. 25/2/2003 14/3/2003 80 km/hr 140 km/hr 2 Tires blown

  26. 25/2/2003 14/3/2003 140 km/hr 80 km/hr 2 Rollovers

  27. 25/2/2003 14/3/2003 Passenger25 years old (driver’s son) Very badly Injured Will he ever recover? Driver: Minor scratches and bruises 140 km/hr 80 km/hr Driver:Dead 1 Dead1 Badly Hurt No Injury

  28. 2 RTA’s: what differences?

  29. The difference is: Speed (= kinetic energy)

  30. Rollovers happen when combining: - (high) speed- sudden change of direction- (braking when changing direction) ALL caused by: THE DRIVER! .

  31. The classic “S” curve rollover: Mistake 1: lost concentration / tyre blow car moves slowly to the right (or left) Driver suddenly realises this !! Mistake 2: pull hard left could roll here already Roll? Mistake 3: pull hard right Roll!! Mistake 4: braking & turning at the same time

  32. A rollovers happens when combining: - (high) speed- sudden change of direction- braking when changing direction ALL caused by: THE DRIVER! . He does this because of: • Lack of concentration and “suddenly” appearing other road users • Tiredness (falling asleep) • Entering a dust cloud • Tyre blowout (not often) • Mechanical failure (not often)

  33. The classic “S” curve rollover: How to avoid it !!! Mistake: lost concentration / tyre blown car moves slowly to the right (or left) Good re-action: Roll-out into the desert. Do NOT pull your steering wheel. Hold it tight and straight with 2 hands. Brake slowly to full STOP. Do NOT panic.

  34. 4WD and Rollovers Are they better or worse than 2WD ?

  35. 4WD are great cars: • strong (we think) • goes anywhere (almost) • never get stuck • sit high (good view) • powerful & feel good (macho?) • comfortable • carry big loads / many passengers BUT…….

  36. But 4WD: • High CoG: sensitive to rollovers • Heavy: poor braking • Steering/cornering: not great • False sense of security: invulnerable at speed • Powerful & fast: much too fast for handling ability

  37. Low CoG Centre of Gravity High CoG Would you drive these cars in the same manner when taking a corner or bend ? Of course NOT !4WD High CoG car: adjust your driving & speed.

  38. When driving (especially for 4WD): • Adjust your driving style. • Speed • Steering: no sudden direction changes • Braking: earlier, more distance • Keep heavy loads low: NOT on the roof! • Keep loads balanced: centre/middle. • Passengers are load: they change the stability of the car.

  39. How can you prevent Rollovers? Remember the Physics! • SpeedSlow down ! • Turn: not turning • Wrong reaction? Train yourself NOT to oversteer – roll out straight and NOT to brake! • Turn: not getting surprised • Lack of concentration? Concentrate! • Tiredness? STOP, rest, have a nap! • Dust? Do NOT enter the dust cloud! • Other road users? Drive defensively • Tyre blowouts? Check condition, pressure • Lower COGUse a 2WD instead of a 4WD Load cars “low” and “centred”

  40. I am in a rollover ! WHAT will protect me?

  41. I am in a rollover ! WHAT will protect me? • roll-bar • seat belts

  42. Seat belt in a rollover: Keeps you INSIDE the car Video 3 Video 4

  43. v v=0 F d M = mass (kg) v = speed (m/s) Seatbelt physics Kinetic Energy: ½ Mv2 = F x d This energy is dissipated by braking (force F) over a distance (d)

  44. M = mass (kg) v = speed (m/s) Seatbelt physics Increase the stopping distance (d) Reduce the force on the body (F) Force on 50 kg body (kgf) G-Force on a body V5

  45. Seat belt: The “UNBELTED” person Video 6 Video 7 Video8

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