Presented to: Committee for the Study of a Motor Vehicle Rollover Rating System May, 29 2001

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Presented toCommittee for the Study of a Motor
Vehicle Rollover Rating SystemMay, 29 2001
Collection of NASS CDS Data Relating to Rollover
Robert Woodill Veridian Engineering John Brophy
NHTSA
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NASS CDS Rollover Variables

• A rollover is defined as any vehicle rotation of
  90 degrees or more about any true longitudinal or
  lateral axis.
• The variables also attempt to identify
• What initiated the rollover
• At what plane of the vehicle exterior the
  tripping force was applied and
• The direction of the initial roll.

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NASS CDS Rollover Variables (continued)
CDS Data Collection Screen
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NASS CDS Rollover Variables (continued)

• Rollover Data
• Type
• Quarter Turns

• Rollover Initiation
• Type
• Location
• Object Contacted Class
• Object Contacted

• Rollover Specifics
• Location on Vehicle Where Initial Tripping
• Force Applied
• Direction of Initial Roll

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NASS CDS Rollover Variables (continued)

• Element Attributes
• Trip-over
• Flip-over
• Turn-over (justify)
• Climb-over
• Fall-over
• Bounce-over

• Collision with
  
  another vehicle
• Other rollover initiation type (specify)
• Unknown
• End-over-end

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NASS CDS Rollover Variables (continued)

• Element Attributes (continued)
• Most Popular One is the

Cherry Turn-Over
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NASS CDS Rollover Variables (continued)

Source for coding rollover variables in CDS
NASS Researcher determined primary sources are
the scene and vehicle inspections. Secondary
sources are photographs, police report, driver
interviews, and other interviewees.
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Trip-Over

• Example 1 Vehicle lateral motion is resisted
  by opposing force (curb) at wheels, inducing
  roll moment.

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Trip-Over (continued)

• Example 2 Vehicle lateral motion is resisted by
  opposing force (surface friction)at wheels,
  inducing roll moment. Tire side wall breaks down
  and rim gouges usually occur.

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Right Right Rear Front
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Trip-Over (continued)

• Example 3 Vehicle lateral motion is resisted by
  opposing force (surface friction) at wheels,
  inducing roll moment. Wheels dig into soft soil
  causing trip.

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Trip-Over (continued)

• Example 4 Vehicle lateral motion is resisted by
  opposing force (surface friction) at wheels,
  inducing roll moment. Incline helps cause side
  wall to break down and rim to dig in causing trip.

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Right Right Rear Front
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Left Left Front Rear
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Flip-Over

• Example 1 Forward moving vehicle is vigorously
  rotated about its longitudinal axis by a ramp
  like object such as a guard rail taper.

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Flip-Over (continued)

• Example 1 Forward moving vehicle is vigorously
  rotated about its longitudinal axis by a
  ramp-like object such as a steep embankment.

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Turn-Over

• Centrifugal forces from a sharply turning or
  rotating vehicle produce a rollover moment when
  resisted by surface friction

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Turn-Over ?
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Roof Left Side Damage
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Left Side Wheel Damage
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Left Rear Wheel Damage
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Turn-Over or Trip-Over

• Heavier damage to right side of roof indicates
  that the left side was probably leading.
• Damage to left side wheels verifies that the left
  side was leading and that it is a Trip-Over
  rather than a turn-over.

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Climb-Over

• Vehicle climbs up and over a fixed object such as
  a barrier or guardrail

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Fall-Over

• Vehicle is tipped by slope so that its center of
  gravity is outboard of its wheels.

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Fall-Over?
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Fall-Over or Trip-Over?
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Left Side Wheel Damage
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Close-up LF Wheel Damage
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Fall-Over or Trip-Over?

• Note left side wheel damage
• Indicates that the left side was leading
• Verifies that this is a trip-over rather than a
  fall-over

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Bounce-Over

• Vehicle rebounds off fixed object (such as a
  guardrail), and overturns as a consequence

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However, If

• Instead of rebounding, the vehicle climbs over
  the fixed object (such as a guardrail), and
  overturns on the opposite side

It becomes a?
Climb-Over
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Impact With Another Vehicle

• Rollover is the immediate result of an impact
  with another vehicle.
• Momentum from the impact causes vehicle to
  turn-over, no tripping is involved

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Vehicle Impact or Trip-Over
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Right RightRear Front
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Left Side Roll Damage
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Roll and LR Wheel Damage
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Roll and LF Wheel Damage
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Left Front
Left Rear
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Vehicle Impact or Trip-Over

• Vehicle/vehicle impact was the impetus to send
  this vehicle into curb but,
• The curb impact was the initiator for the
  rollover and thus this is a TRIP-OVER.

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Tripped or Untripped?
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Left Front
Left Rear
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Conclusion

• Scrutiny of both scene evidence and vehicle
  damage -- especially the wheels is critical.
• Close-up images of the wheels are very important.

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Questions