Rollovers & Seatbelts

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Rollovers & SeatbeltsRollovers & Seatbelts

RolloversRollovers

& Seatbelts& Seatbelts

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What is a “ROLLOVER”?What is a “ROLLOVER”?

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What is a “ROLLOVER”?What is a “ROLLOVER”?

• a single vehicle incidenta single vehicle incident• vehicle “rolls” 90 deg or morevehicle “rolls” 90 deg or more

• ““driver looses control”driver looses control”

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Does PDO have manyDoes PDO have many

““ROLLOVERS”?ROLLOVERS”?

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PDO: many rollovers every year!PDO: many rollovers every year!

20002000 20012001 20022002 20032003 20042004 20052005 20062006 2007 td2007 td

RolloversRollovers 4343 3333 2222 2222 2121 4545 5454 4545

Km Km 118118 123 123 133133 139 139 145 145 151 151 161 161 175 175

RolloversRollovers

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19-Oct-2007: on the way to Bahja

Driver: seatbelt – minor injuryPassenger: Seatbelt – minor injuryPassenger: NO seatbelt - DEAD

Rollover !!Rollover !!

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9-Sept-2007: on the way to Haima

Driver: NO seatbelt - DEADPassenger: NO seatbelt - DEADPassenger: Seatbelt – minor injury


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


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Rollovers & SeatbeltsRollovers & Seatbelts23-Oct-2006

Marmul-Thumrait 7 km before Harweel junction

Driver: 39 yrs old, diedSpeed: at least 140 km/hr

PDO Spec vehicle: tampered!Seatbelt did not help anymore


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March/2001 March/2001

Maqbool Maqbool & &

Faisal Faisal DiedDied

Anything that goes wrong Anything that goes wrong at high SPEED is a BIG problem!!at high SPEED is a BIG problem!!

150 km/hr150 km/hr

TyreTyreblewblew


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30/Oct/01 LTI 30/Oct/01 LTI Permanent Total DisabilityPermanent Total Disability

Veered off to the rightVeered off to the rightOvercorrected, rolled 4xOvercorrected, rolled 4xClassic S patternClassic S patternNO rollover barNO rollover bar

Straight blacktop Fahud-NahadaStraight blacktop Fahud-Nahada


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Rollover !Rollover !

!!

Blacktop road Fahud- NizwaBlacktop road Fahud- Nizwa

Car moved right at high Car moved right at high speed. Driver over corrected speed. Driver over corrected and got into an S pattern:and got into an S pattern:Rolled & Flipped.Rolled & Flipped.

20/Nov/01 Fatality & LTI20/Nov/01 Fatality & LTI

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2 man came out alive. 2 man came out alive. They were wearing their They were wearing their seatbelts. seatbelts.

1 man DIED. He was 1 man DIED. He was NOT wearing his NOT wearing his seatbeltseatbelt

NO SeatbeltNO Seatbelt= DEATH= DEATH

Nimr to Muscat 13th June 98Nimr to Muscat 13th June 98

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What would you “prefer”?What would you “prefer”?

a Rollovera Rolloveroror

a Head on Collisiona Head on Collision

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Rollovers are killers!Rollovers are killers!

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

Co

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ion

Co

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ixed

Ob

ject

Ro

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Ru

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(ped

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Ru

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(an

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Traffic accidents breakdown per type in 1999/2004

2004 2003 20022001 2000 1999

0

50

100

150

200

250

Co

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Co

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wit

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ixed

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(an

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Fatalities per accident type 1999/2004

2004 2003 20022001 2000 1999

No of accidents No of death

Video 1Video 2

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Common features of rollovers:Common features of rollovers:

• Speed (80 km/hr can be too fast !!)Speed (80 km/hr can be too fast !!)

• Mostly 4 WD (high Mostly 4 WD (high CCentre entre oof f GGravity cars)ravity cars)

• Most on straight roadsMost on straight roads

• Most classic “S” curves Most classic “S” curves

• Many on blacktop roads at high speedMany on blacktop roads at high speed

• Few: tyre blow-out, junction/speedFew: tyre blow-out, junction/speed

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Why does a vehicle roll ?Why does a vehicle roll ?

How many rolls will it do ?How many rolls will it do ?

Simply Physics !Simply Physics !

Understand the physicsUnderstand the physics

to understand the controls……to understand the controls……

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We have a “vehicle at speed”: why does it roll?We have a “vehicle at speed”: why does it roll?

Gravity Force Gravity Force GF = M x g (= constant)GF = M x g (= constant)

MM = = mass (kg)mass (kg)vv = = speed (m/s)speed (m/s)gg = = gravitationalgravitational

accelerationacceleration

CCentre entre oof f GGravityravity

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Why does it roll?.... Because of centrifugal force!Why does it roll?.... Because of centrifugal force!


Centrifugal Force (CF)Centrifugal Force (CF)

MM = = mass (kg)mass (kg)vv = = speed (m/s)speed (m/s)r r = = turn radius (m) turn radius (m) gg = = gravitationalgravitational



MvMv22 CF= CF= --------------

r r

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Why does it roll?.... Because of centrifugal force!Why does it roll?.... Because of centrifugal force!


Centrifugal Force (CF)Centrifugal Force (CF)

MM = = mass (kg)mass (kg)vv = = speed (m/s)speed (m/s)r r = = turn radius (m) turn radius (m) gg = = gravitationalgravitational


CF increases with:CF increases with:- v higher (higher speed)- v higher (higher speed)- r smaller (sharper turn)- r smaller (sharper turn)


MvMv22 CF= CF= --------------

r r

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Rollovers & SeatbeltsRollovers & SeatbeltsWe have a “rolling vehicle at speed” We have a “rolling vehicle at speed”


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Rollovers & SeatbeltsRollovers & SeatbeltsWe have a “rolling vehicle at speed” We have a “rolling vehicle at speed”


Kinetic Energy: ½ MKinetic Energy: ½ Mvv22

This energy is dissipated during the rollsThis energy is dissipated during the rollsMore energy more rolls!More energy more rolls!

Energy goes up with the square of the speed!Energy goes up with the square of the speed!

MM = = mass mass (kg)(kg)

vv = = speed speed (m/s) (m/s)

Km/hr Energy in % of 100 km/hr80 64%100 100%120 144%140 196%

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Next 4 slides:Next 4 slides:

- 2 RTA’s are shown2 RTA’s are shown

- they are almost the samethey are almost the same

- compare themcompare them

- see what the differences aresee what the differences are

- discuss why the outcome was differentdiscuss why the outcome was different

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2 Black Top Roads2 Black Top Roads2 Cars driving2 Cars driving

140 km/hr140 km/hr 80 km/hr80 km/hr

25/2/200325/2/2003 14/3/200314/3/2003

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2 Tires blown2 Tires blown


25/2/200325/2/2003 14/3/200314/3/2003

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2 Rollovers2 Rollovers

140 km/hr140 km/hr80 km/hr80 km/hr

25/2/200325/2/2003 14/3/200314/3/2003

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PassengerPassenger25 years old 25 years old (driver’s son)(driver’s son)

Very badly Very badly InjuredInjured

Will he ever Will he ever recover?recover?Driver:Driver: DeadDead

1 Dead1 Dead1 Badly Hurt1 Badly Hurt

Driver: Driver:

Minor Minor scratches scratches

and bruisesand bruises

No InjuryNo Injury

25/2/200325/2/2003 14/3/200314/3/2003


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2 RTA’s:2 RTA’s:

what differences?what differences?

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The difference is:The difference is:

SpeedSpeed(= kinetic energy)(= kinetic energy)

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Rollovers happen when combining:Rollovers happen when combining:

- (high) - (high) speedspeed - sudden - sudden change of directionchange of direction - (- (brakingbraking when changing direction) when changing direction)

ALL caused by: ALL caused by: THE DRIVERTHE DRIVER! ! ..

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The classic “S” curve rollover:The classic “S” curve rollover:

Mistake 2: pull hard leftMistake 2: pull hard left could roll here already could roll here already

Mistake 3: pull hard right Mistake 3: pull hard right

Mistake 1: lost concentration / tyre blowMistake 1: lost concentration / tyre blow car moves slowly car moves slowly to the right (or left) to the right (or left)

Driver suddenly realises this !!Driver suddenly realises this !!

Mistake 4: braking & turningMistake 4: braking & turning at the same time at the same time

Roll!! Roll!!

Roll? Roll?

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Rollovers & SeatbeltsRollovers & SeatbeltsA rollovers happens when combining:A rollovers happens when combining:

- (high) - (high) speedspeed - sudden - sudden change of directionchange of direction - - brakingbraking when changing direction when changing direction

ALL caused by: ALL caused by: THE DRIVERTHE DRIVER! ! ..

He does this because of:He does this because of:

• Lack of concentrationLack of concentration and “suddenly” and “suddenly” appearing other road usersappearing other road users

• Tiredness (falling asleep)Tiredness (falling asleep)

• Entering a dust cloudEntering a dust cloud

• Tyre blowout (not often)Tyre blowout (not often)

• Mechanical failure (not often)Mechanical failure (not often)

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Rollovers & SeatbeltsRollovers & SeatbeltsThe classic “S” curve rollover:The classic “S” curve rollover:

How to avoid it !!!How to avoid it !!!

Good re-action: Good re-action: Roll-out into the desert.Roll-out into the desert.Do NOT pull your steering Do NOT pull your steering wheel. Hold it tight and wheel. Hold it tight and straight with 2 hands.straight with 2 hands.Brake slowly to full STOP.Brake slowly to full STOP.Do NOT panic.Do NOT panic.

Mistake:Mistake:lost concentration / tyre blownlost concentration / tyre blown car moves slowly car moves slowly to the right (or left) to the right (or left)

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4WD and Rollovers4WD and Rollovers

Are they better or worse Are they better or worse than 2WD ? than 2WD ?

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4WD are great cars: 4WD are great cars:

• strong (we think)strong (we think)

• goes anywhere (almost)goes anywhere (almost)

• never get stucknever get stuck

• sit high (good view)sit high (good view)

• powerful & feel good (macho?)powerful & feel good (macho?)

• comfortablecomfortable

• carry big loads / many passengerscarry big loads / many passengers

BUT…….BUT…….

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But 4WD:But 4WD:

• High CoG: sensitive to rolloversHigh CoG: sensitive to rollovers

• Heavy: poor brakingHeavy: poor braking

• Steering/cornering: not greatSteering/cornering: not great

• False sense of security: invulnerable at speedFalse sense of security: invulnerable at speed

• Powerful & fast: much too fast for handling abilityPowerful & fast: much too fast for handling ability

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Would you drive these cars in the same manner when taking a corner or bend ? Would you drive these cars in the same manner when taking a corner or bend ? Of course NOT !Of course NOT !

4WD High CoG car: adjust your driving & speed.4WD High CoG car: adjust your driving & speed.

Low CoGLow CoG


High CoGHigh CoG

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When driving (especially for 4WD):When driving (especially for 4WD):

• Adjust your driving style. Adjust your driving style.

– SpeedSpeed

– Steering: no sudden direction changesSteering: no sudden direction changes

– Braking: earlier, more distanceBraking: earlier, more distance

• Keep heavy loads low: NOT on the roof! Keep heavy loads low: NOT on the roof!

• Keep loads balanced: centre/middle.Keep loads balanced: centre/middle.

• Passengers are load: they change the stability of the car.Passengers are load: they change the stability of the car.

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Rollovers & SeatbeltsRollovers & SeatbeltsHow can you prevent Rollovers? Remember the Physics!How can you prevent Rollovers? Remember the Physics!

• SpeedSpeed Slow down !Slow down !

• Turn: not turningTurn: not turning

– Wrong reaction? Wrong reaction? Train yourself Train yourself NOT to oversteer – roll out NOT to oversteer – roll out

straightstraightand NOT to brake! and NOT to brake!

• Turn: not getting surprisedTurn: not getting surprised– Lack of concentration? Lack of concentration? Concentrate!Concentrate!– Tiredness? Tiredness? STOP, rest, have a nap!STOP, rest, have a nap!– Dust? Dust? Do NOT enter the dust cloud!Do NOT enter the dust cloud!– Other road users?Other road users? Drive defensivelyDrive defensively– Tyre blowouts? Tyre blowouts? Check condition, pressureCheck condition, pressure

• Lower COGLower COG Use a 2WD instead of a 4WDUse a 2WD instead of a 4WDLoad cars “low” and “centred”Load cars “low” and “centred”

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I am in a rollover !I am in a rollover !

WHAT will protect me?WHAT will protect me?

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I am in a rollover !I am in a rollover !

WHAT will protect me?WHAT will protect me?

• roll-bar roll-bar

• seat beltsseat belts

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Seat belt in a rollover:Seat belt in a rollover:

Keeps you Keeps you

INSIDE INSIDE

the carthe car

Video 3Video 4

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Rollovers & SeatbeltsRollovers & SeatbeltsSeatbelt physicsSeatbelt physics

Kinetic Energy: ½ MKinetic Energy: ½ Mvv22 = F x d = F x d

This energy is dissipated by This energy is dissipated by braking (force F) over a distance (d)braking (force F) over a distance (d)


vv = = speed speed

(m/s)(m/s)

F d

v v=0

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Stopping Distance (m) Stopping Distance (m)1 0.5 0.1 1 0.5 0.1

Speed (km/hr) Stopping Force (kgf) Stopping Force (g)

40 300 600 3,100 6 12 62

60 695 1,390 6,950 14 28 139

80 1,240 2,500 12,400 25 49 247

100 1,900 3,900 19,300 39 77 386

120 2,800 5,600 27,800 56 111 556

Force on 50 kg body (kgf) G-Force on a body

Seatbelt physicsSeatbelt physics

Increase the stopping distance (d)Increase the stopping distance (d)Reduce the force on the body (F)Reduce the force on the body (F)


vv = = speed speed

(m/s)(m/s)

V5

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Video 6Video 7Video8

Seat belt:Seat belt:

The “The “UNBELTED”UNBELTED” person person

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Documents

Rollovers & Seatbelts