Insurance company Allianz is advising motorists to carefully pack car roof boxes before setting off on any journey.
Recent crash tests conducted by Allianz Munich showed that poorly packed roof boxes can explode on impact and spew their contents with the force of several tonnes due to the impact in a car crash. In effect, it becomes a cannon.
The video shows how quickly a poorly loaded roof box can compound the potential injuries of a car crash. The test was conducted using a standard 380 litre roof box packed with skis and associated equipment.
"In a crash of 30mph, where the car suddenly goes from 50km/h to 0km/h, the contents of the roof box will retain the force of travelling at 50km/h. Your car takes three seconds to stop when you brake at 50km/h, but in a crash, that time can shorten to .01 second meaning the force can be up to 150 times the force of gravity," says Brendan Murphy, CEO Allianz Ireland. A 380 litre box with a load capacity of 60kg, under 150 times the force of gravity can become a cannon and shoot out contents, which could add to injuries sustained during a car accident."
Allianz 10 tips for safer roof box driving:
1. Check your car's manual to make sure that the load, including the weight of the roof rack itself, doesn't exceed the maximum. This limit tends to be quite low.
2. Be aware that a fully loaded car (with or without a roof box) will require more breaking distances.
3. Under heavy breaking the load will tend to slide forwards - accelerate and brake gently.
4. A roof box can alter your car's centre of gravity so take corners at a lower speed.
5. Put heavier items at the bottom of the roof box and lighter items on top.
6. Do not exceed the recommended load capacity of a roof box.
7. Don't forget the extra height when entering underground car parks or entrances with lower height.
8. Take care, for example, when entering covered car parks.
9. Distribute weight safely in a roof box.
10. Check your tyre pressures - consult the manual to see if you need to increase or decrease your tyre pressures to cope with the extra weight.