Mumsnet Talk

There have been quite a few threads on this over the past few years. There has been an article in the BMJ advising that rear-facing car seats are safer for children under 4.

Quote from ROSPA website "Research shows they provide greater protection for children up to 18kg (40lbs), and RoSPA supports calls to make these rearward-facing seats for older toddlers more widely available here in the UK as it would improve parental choice about the safety of their children."

Toddlers' heads are big and heavy and their necks are weak. The forces involved in a crash tend to put a lot of strain on the necks of babies and young-children in forward-facing seats. For children in rear-facing seats, the forces in a crash distribute the strain over a larger area, and thus subject the body to less strain.

The Sunday Times did an article a few months ago on the benefits of rear-facing seats.

Despite this, most retailers in the UK don't sell them. It's not because they don't exist - the most popular brands of car seat in the UK make rear-facing seats, but sell them only in Scandinavia and mainland Europe where the safety message has permeated better. There are a few specialist centres, but mostly parents have to buy over the internet. John Lewis now sells a rear-fitting seat, but only in-store: it's a start, but it could be better.

If MN had a campaign on this, we could persuade the major retailers to change things. Rear-facing seats already exist and are widely available in parts of Europe. There is a big range available in Scandinavia - ones that will fit in small cars as well as big cars. Parents aren't buying them at the moment because most don't know about them, and the ones that do want a rear-facing seat have to travel a long way to buy and fit one.

Anyone else?

Only if you are running into someone, if you are hit from behind they are not as good.

a campaign to get the shops to stock more????

What are the statistics on rear shunts and these seats?
What is the most common type of collision?

Seen lots of claims that rear end shunts are the most common but have not found eny concrete statistics yet. Surely to have a rear shunt you also have a statistic for 'being shunted from behind'? Will keep looking.

Rear end collisions are usually at low speed with one car stationary which lessen the impact.

If car A runs into the back of car B, car A is doing 80mph and car B is doing 60mph then the relative speed of the crash is 20mph (both vehicles traveling in the same direction). The weight (in kg) of the occupants is multiplied by the force (i.e. 8.9m/s).

If car A crashes head on into car B, car A is doing 50mph and car B is doing 50mph then the relative speed of the crash is 100mph. The weight (in kg) of the occupants is multiplied by the force (i.e. 45m/s).

In a rear facing seat in a head on crash the crash forces are spread across the whole back and the head is supported by the seat back. In a forward facing seat in a head on crash the body is held back by the harness but the limbs and the head are free to keep travelling in the original direction/speed.

BMJ study
A website set up for a survivor of a ffing crash
Rearfacing website

Those are interesting links TruthSweet, thanks.

This also has the videos of the safety tests.

I would be really interested in this. I recently tried to purchase a RF seat and neither mother care, JL or babies are us stock any BUT the shop assistants I spoke to knew about them and was very aware.

OnlyWantsOne, John Lewis sell the Recaro Polaric but it's pretty big and only Isofix.

Thanks for the info TruthSweet but it appears you are only describing the forces affecting the child in Car B?

Marking my place

No I am explaining the forces acting on both cars. The speed of the impact is the same on both vehicles. In a head on crash both vehicles are both going forward (from their perspective) so the crash forces are that all the occupants of both the vehicles continue in the original direction (forward) but at the crash speed (for situation 1 that was 8.9m/s and for situation 2 that was 45m/s).

In situation 1, a 10kg forward facing child would have a mass of 89kg (25% of this is their head 22.5kg), all of which except the body would be travelling at 8.9m/s forward nothing to restrain the head or limbs or to stop them moving forward (As you can see in the videos in the link below). Broken bones are common as legs/arms are thrown forward against the front seat backs and broken necks (aka internal decapitation) are a cause of death or paralysis.

In situation 1, a 10kg rear facing child would again have a mass of 89kg (25% of this is their head 22.5kg), except this time the whole body would be supported by the back of the car seat and 'ride down' would happen (body moves upwards with the force of the impact but as rfing carseats the straps should come from below or at the shoulders the child doesn't have much upward movement and 'rides down' the impact). Limbs move upwards and back down against the child seat (As you can see in the videos in the link below). Broken bones are not very common but much more easily repaired than an internal decapitation.

In situation 2, a 10kg forward facing child would have a mass of 450kg (25% of this is their head - 112.5kg), all of which except the body would be travelling at 45m/s forward (nothing to restrain the head or limbs). Broken bones are common as legs/arms are thrown forward against the front seat backs and broken necks are a cause of death or paralysis.

In situation 1, a 10kg rear facing child would again have a mass of 450kg (25% of this is their head - 112.5kg), except this time the whole body would be supported by the back of the car seat and 'ride down' would happen as in situation 1. Limbs are thrown upwards and back down against the child seat.

http://www.rearfacing.co.uk/facts.php

Does that help?

The BMJ article explains things very well. And is a peer-reviewed piece of scientific research:

"Results and conclusions
It concluded that rear facing seats were more effective than forward facing seats in protecting children aged 0-23 months for all crash types (odds ratio 1.76, 95% confidence interval 1.40 to 2.20). Effectiveness estimates compared with no restraint were 93% for rear facing seats and 78% for forward facing seats. These were calculated using estimates of the percentage reduction in rate of injury if all children changed from being unrestrained to being users of the particular car seat type. In side impacts, children were much more likely to be injured in forward facing seats (5.53; 3.74 to 8.18). When children aged 12-23 months were analysed separately, the findings remained: children in forward facing seats were much more likely to be injured (5.32; 3.43 to 8.24)."

yes: definitely. We've just bought a forward facing one and then read all the research and realised it was not the best plan. Just having more information available would be good!

until I found musmnet I had no idea rear facing seats existed

what about car sickness from having to travel everywhere backwards?

and where do they put their legs?

genuinely interested

But now you are describing a head on crash not a rear shunt? Irrespective of the forces, a forward facing car seat, in the front car, hit from behind is safer than a rear facing car seat in the front car that is hit from behind.

I agree that rear facing seats are safer when the child is suddenly involved in a sharp deceleration, such as a head on crash or running into a car from behind. I am wondering about a child in the front car facing sudden acceleration when hit from behind by a shunt which is the most common type of accident.

If you are in the most common type of accident it appears to be a 50/50 chance to be in either car.

Trinity,

Rfing children's legs are put in the boot.


Only joking.

Legs go criss-cross, flung over either side of the seat, on the back of the seat (upwards), straight on shorter legged children. Have a look at the gallery here for real life children in their own car seats.

The front car is still being pushed forward at 20mph.

If car A runs into the back of car B, car B is doing 80mph and car A is doing 60mph then the relative speed of the crash is 20mph (both vehicles traveling in the same direction). The weight (in kg) of the occupants is multiplied by the force (i.e. 8.9m/s).

Car A is hit by car B

B is 80mph moving forwards
A is 60mph moving forwards

80-60 = 20mph (this is the residual speed left over from the force of car B travelling at 80mph into car A travelling at 60mph).

The relative speed is 20mph forwards.

Both cars are subject to the force of 20mph forwards.

So any passengers in BOTH cars move forwards at 20mph.

The rfing child would travel at 20mph into the back of their seat with the crash forces spread across the back of their whole body.

The ffing child would have just their head and limbs traveling at 20mph as their body would be restrained by their harness. The child (if 10kg) would have approx a 22.5kg head due to the crash forces.

Does that make things clearer?

No, you are incorrect with your dodgy linear mechanics and forces, we can discuss conservation of momentum and relativity all day but you seem to be confusing speed and acceleration.

In simple terms the issue is not the speed they are now travelling, it is new force acting on the child (newtons first and second laws) as it's car is hit in a rear end shunt. It is then subject to a force which (as your seem to have tried to work out) is its mass multiplied by its acceleration.

It is a simple thing to undertsand, the slower car in front is hit, causing the car to accelerate and the force of this acceleration causes the child in the front car to be pushed backwards (relatively speaking).

Think about it, if you are hit from behind or if you accelerate hard, you are pushed back into your driving seat (which I hope is forward facing).

The rear car, causing the shunt, is subject to a negative acceleration (just like applying the brakes hard) or deceleration which pushes the occupants towards the front of the car. In this case, a rear facing seat would be better.

To sum up, a child in a car that is hit from behind is pushed backwards into the backrest of a forward facing seat. A child in a rear facing seat in the front car is subject to the same disadvantages as the child in the car behind in its forward facing seat.

Please dont try to over complicate it, we all know from experience that if a car is accelerating you are safer with the seat facing forwards, decelerating you are safer with a rear facing seat.

The moral of the story is I should know when to shut up.

It is your brain ricocheting in your head that does the damage -so does that make a real difference to which way the seat is facing in terms of brain injury?

scurry the point is for smaller children, the stretching and jerking forward of the neck can do most damage as their heads are large relative to their bodies and their necks are small and weak. The study of injuries in both types of seat concluded that small children were safer facing backwards. Brains will no doubt richochet whichever way you face - the point is that the research has demonstrated that there is a statistically significant difference in the occurence and severity of injury depending on which way a child is facing.

I back this. I understand many European countries insist on rear-facing and that in the UK apparently parents prioritise style over safety

And for JBellingham an expanation of the relative risks of head-on and rear-end collisions wrt rear-facing seats here.