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Evaluation of LATCH vs. non-LATCH installations for boosters in frontal impacts

Presenter: Julie Mansfield, PhD�Co-authors: Gretchen Baker, Rakshit Ramachandra, John Bolte IV

The Ohio State University

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BACKGROUND

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BACKGROUND

There are two different methods to install boosters:

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BACKGROUND

There are two different methods to install boosters:

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“Lower Anchors and Tethers for CHildren”

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BACKGROUND

There are two different methods to install boosters:

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BACKGROUND

Manufacturers’ instructions can vary regarding the acceptable ways to install a certain product in booster mode:

  • LATCH not allowed, can be used, encouraged but not required, or required
  • LA allowed, no top tether available

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OBJECTIVES

  • When LATCH is optional for booster mode, which method should be used?
    • Always use the manufacturer’s recommended method, if there is one!
  • How should parents and child passenger safety technicians (CPSTs) navigate this situation with caregivers?

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EXAMPLES OF INSTRUCTIONS

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EXAMPLES

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EXAMPLES

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EXAMPLES

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EXAMPLES

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EXAMPLES

Most boosters require securement when unoccupied:

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PROS & CONS

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PROS & CONS

  • Potential pros of using LATCH:
    • Prevents unoccupied booster from becoming projectile

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“An object in motion will remain in motion….”

Alternative: Buckle seat belt around unoccupied booster for every trip.

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PROS & CONS

  • Potential pros of using LATCH:
    • Stabilizes booster as child climbs in and out

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Image: Shutterstock

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PROS & CONS

  • Potential cons of using LATCH:
    • More difficult to transfer booster from one vehicle to another.
      • Would LATCH discourage a parent from transferring the booster to another vehicle if needed?
        • Some designs are easier to install/uninstall than others.

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PROS & CONS

  • Potential cons of using LATCH:
    • More difficult to transfer booster from one vehicle to another.
      • Would LATCH discourage a parent from transferring the booster to another vehicle if needed?
        • Some boosters are easier to install/uninstall than others.

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PROS & CONS

  • Potential cons of using LATCH:
    • More difficult to transfer booster from one vehicle to another.
      • Would LATCH discourage a parent from transferring the booster to another vehicle if needed?
        • Some boosters are easier to install/uninstall than others.

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PROS & CONS

  • Potential cons of using LATCH:
    • Lower anchors might be offset (mis-aligned) from seat belt position or interfere with adjacent seat belts.

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Image: The Car Seat Lady

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WHAT HAPPENS DURING A CRASH?

  • How is booster mass controlled?

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WHAT HAPPENS DURING A CRASH?

    • Could child de-couple from the booster?

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Images: Tylko S, Bussieres A, Starr A. Evaluating child safety innovations: Have we got the right tools and the right test methodologies? Proceedings from The Protection of Children in Cars Conference. Munich, Germany. December 2016.

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GOALS OF SLED TESTING

  • Goal: Produce data to support industry guidelines and best practice for booster installation methods, particularly when LATCH use is optional.
  • Remember: Manufacturers do their own extensive in-house testing!
    • Always follow manufacturers’ guidelines!

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TEST MATRIX: SLED TESTING

Booster

LATCH condition

Booster Weight (lbs)

Repetitions

High-back 1

None

9

1

High-back 1

Flexible LA + top tether

9

1

High-back 2

None

14

2

High-back 2

Flexible LA

14

2

High-back 3

None

16

2 (with/without lap belt positioner)

High-back 3

Rigid LA

16

2 (with/without lap belt positioner)

High-back 4

None

25

1

High-back 4

Flexible LA + top tether

25

1

Backless 1

None

5

2

Backless 1

Rigid LA

5

2

Backless 2

None

5

1

Backless 2

Flexible LA

5

1

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Total: 18

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VEHICLE SEATS

  • Popular vehicle, 2-door
  • LATCH and seat belt in realistic locations
  • Key components replaced after every test

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CRASH TEST DUMMY (ATD)

  • Hybrid III 6-year-old
    • Used in US regulatory testing
      • 44.9 inches
      • 51.6 lbs

SLED PULSE

  • FMVSS 213 frontal impact
    • 25 g, 48 kph (30 mph)

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RESULTS:

High-back 1

  • Flexible lower anchors
  • Top tether

BELT

LATCH- FLEX

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RESULTS: HIGH-BACK 1

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RESULTS:

High-back 2

  • Flexible lower anchors
  • No top tether

BELT

LATCH- FLEX

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RESULTS: HIGH-BACK 2

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RESULTS:

Backless 1

  • Rigid LATCH

BELT

LATCH- RIGID

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RESULTS: BACKLESS 1

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RESULTS: BACKLESS 1

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RESULTS

Head displacement, x

Head displacement, x (mm)

High-back 1

High-back 2

High-back 2

High-back 3

High-back 3 w/ LBP

High-back 4

Backless 1

Backless 1

Backless 2

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RESULTS

Booster displacement, x

Booster displacement, x (mm)

High-back 1

High-back 2

High-back 2

High-back 3

High-back 3 w/ LBP

High-back 4

Backless 1

Backless 1

Backless 2

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RESULTS

FMVSS 213

Bad x-accel

Head injury criterion (HIC36)

High-back 1

High-back 2

High-back 2

High-back 3

High-back 3 w/ LBP

High-back 4

Backless 1

Backless 1

Backless 2

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RESULTS

Mertz et al. 2016

High-back 1

High-back 2

High-back 2

High-back 3

High-back 3 w/ LBP

High-back 4

Backless 1

Backless 1

Backless 2

Chin-to-chest contact

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RESULTS

Chin-to-chest contact

Belt loading

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RESULTS

FMVSS 213

High-back 1

High-back 2

High-back 2

High-back 3

High-back 3 w/ LBP

High-back 4

Backless 1

Backless 1

Backless 2

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CONCLUSIONS: SLED TESTING

  • For high back boosters, similar performance between LATCH vs. non-LATCH modes.
    • Similar occupant movement
    • Slightly less booster movement
  • For backless boosters, some injury metrics were slightly higher in LATCH mode.
    • Likely due to chin-to-chest contact

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CONCLUSIONS: SLED TESTING

  • No evidence of submarining under the seat belt in either installation mode.
  • All boosters performed well in both installation modes.

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LIMITATIONS

  • Biofidelity of crash dummy
    • Pelvis
    • Neck
  • Limited number of boosters
    • 4 high back, 2 backless
  • One vehicle seat model
    • No front row seat

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ACKNOWLEDGEMENTS

The authors would like to acknowledge the National Science Foundation (NSF) Center for Child Injury Prevention Studies at the Children’s Hospital of Philadelphia (CHOP) and the Ohio State University (OSU) for sponsoring this study and its Industry Advisory Board (IAB) members for their support, valuable input and advice. The views presented are those of the authors and not necessarily the views of CHOP, OSU, the NSF, or the IAB members.

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Evaluation of LATCH vs. non-LATCH installations for boosters in frontal impacts

Presenter: Julie Mansfield, PhD�Co-authors: Gretchen Baker, Rakshit Ramachandra, John Bolte IV

The Ohio State University