Seatbelts and Child Restraints
The Science of Seatbelts
Ever wondered how seatbelts work to protect you in a crash? Well it's all to do with physics.
Inertia: Objects in motion stay in motion; without a seatbelt, your body keeps moving forward at the car's speed even after the car stops.
Momentum & Impulse: Seatbelts increase the stopping time (impulse) for your body, which reduces the force (mass times acceleration/deceleration) exerted on you. This allows your body to absorb crash energy over a longer period, preventing it from being absorbed all at once by your organs and bones.
Wearing a seatbelt can reduce the risk of fatal injury by 40%.
Child Restraints
It’s the law in New Zealand that all children in cars must travel in a child restraint until at least their 7th birthday.
Approved child restraints include:
- infant restraints for young babies (often called baby capsules)
- restraints for older babies, toddlers and preschool children (often called car seats)
- booster seats for preschool and school-aged children
- child safety harnesses (used with or without a booster seat) for preschool and school-aged children.
Before moving your child into a regular seatbelt take the 5-step test:
1. Does you child sit all the way back against the vehicle seat?
2. Do your child's knees bend comfortably at the edge of the vehicle seat?
3. Does the belt cross the shoulder between the neck and the arm?
4. Is the lap bely as low as possible, touching the thighs?
5. Can the child stay seated like this for the whole trip?
If you answered 'no' to any of these questions, your child should remain in a child restraint or booster seat for safety.
South Canterbury Car Seat Trust
The new Child and Restraint Safety Equipment Access and Training (Carseat) Trust SC 2025 launched in December 2025 to make child car seat safety more accessible, affordable and understood across the region.
They will also offer education and training on child restraint safety, and car seats will be available for hire for short or long-term use, with a returnable bond and a simple payment schedule. For more information about the trust or how to access the service, you can contact them on 022 415 3712 or via their Facebook page, CarSeat Trust SC 2025
Plunket Child Restraint Technicians
Plunket have two trained child restraint technicians in our area who can provide advice and support to families on how to correctly install child restraints. You can contact Plunket here.
