Head on collision - choose a tree rather than an oncoming car ?

uberalles · 13-10-2012 9:44am #1

If faced with a car driving towards you is a hitting a tree a better option?

I've heard that a head on crash doubles the speed so is a solid tree a better idea ?

Hopefully I never have to choose but just wondering

Hal Decks · 13-10-2012 9:47am

What a ridiculous post!

corktina · 13-10-2012 9:48am

you'd never know if you made the right choice.

Mena · 13-10-2012 9:49am

Lol

Yeah, oncoming car speed + your speed = speed of the collission, so tree may appear to be a better option, but then there would be hundreds of other factors you'd need to take into account.

phill106 · 13-10-2012 9:53am

Got to factor in what you are hitting. Is it a sapling or a huge oak tree!
There would be some give in cars, with crumple zones and airbags etc, while trees are meant to just stand there solidly.
Can I not just aim for the ditch?!

Bruthal · 13-10-2012 9:53am

Mena wrote: »

Lol

Yeah, oncoming car speed + your speed = speed of the collission, so tree may appear to be a better option, but then there would be hundreds of other factors you'd need to take into account.

Oncoming car at 100kph and you doing 100kph, would probably not be as bad as hitting an immovable object at 200kph in terms of deceleration time. The energy of the impact would be similar probably. So the outcome would be probably equally as bad with the crumpling of the cars.

If you hit an oncoming car that is doing 30kph, and you are doing 100kph, they will be pushed backwards, so again, its probably not the same as hitting something at 90kph which does not budge, the deceleration would probaby be higher hitting a solid tree square on that doesnt move at all.

vicwatson · 13-10-2012 9:55am

Poll ?

The Big Red Button · 13-10-2012 9:56am

Obviously, the combined speed of two moving cars is far higher than the speed of one moving car and a tree. But, as mentioned, there are many other factors involved.

If it was me, I'd absolutely head for the tree. No hesitation. If you're going to be in a head-on collision, you're going to end up pretty f*cked up either way - why create more casualties? There could be children/babies in the back-seat of the other car - how could you live with yourself knowing that you'd made the choice to crash into that vehicle?

seamus · 13-10-2012 10:03am

It's not actually as simple a calculation as above. 100kph + 100kph does not equal hitting a tree at 200kph because the vehicles absorb so much of the energy of the crash. On top of that you're unlikely to hit the other car dead head on, you'll hit eachother at even a slight angle, which reduces the forces involved.
A tree is a scarier prospect because it provides very little give, so most of the force of the crash is transferred to your vehicle. It's circular profile means that hitting it from any angle is a "head on".

For most people I think hitting the tree is most obvious choice because you're only risking your own safety. Go for the other vehicle and you're dragging them into the incident and they could have two kids in the back, etc.

AugustusMinimus · 13-10-2012 10:03am

robbie7730 wrote: »

Oncoming car at 100kph and you doing 100kph, would probably not be as bad as hitting an immovable object at 200kph in terms of deceleration time. The energy of the impact would be similar probably. So the outcome would be probably equally as bad.

In that scenario, you'd take hitting the car, as you would have two crumple zones to disipate the energy of the impact. Trees have no crumple zones.

hardCopy · 13-10-2012 10:03am

Are we talking about an actual on the spot choice of which one to hit? I don't think I'd want to deliberately hit the car but I'd want nothing to do with a mature tree.

A couple of months back a people carrier hit a tree outside our house, not sure how fast he was going but he managed to mount the kerb, cross a bus stop and hit the tree.

The car was a writeoff, two passengers had to be cut out of the car and all 4 required separate ambulances.

The tree had two very small chips in the bark.

afatbollix · 13-10-2012 10:08am

We hate trees in rallying circles. The crashes where most drivers are killed is because they hit trees, They can split a car in two like cheese wire!

corktina · 13-10-2012 10:12am

you would be very unlikely to get the chance to decide which to hit. Altthough people often say that an accident seemed to happen in "slow motion" ,in reality, they usually occur before you can react at all

Bruthal · 13-10-2012 10:14am

AugustusMinimus wrote: »

In that scenario, you'd take hitting the car, as you would have two crumple zones to disipate the energy of the impact. Trees have no crumple zones.

In terms of reducing impact level, probably. But in reality avoiding hitting another car would be preferable.

Stereomaniac · 13-10-2012 10:16am

I can say I'd rather hit the tree, but in the moment, I know it probably wouldn't be like that!

Bruthal · 13-10-2012 10:18am

corktina wrote: »

you would be very unlikely to get the chance to decide which to hit. Altthough people often say that an accident seemed to happen in "slow motion" ,in reality, they usually occur before you can react at all

Yes its an unlikely choice to arise, but probably has at some time by some on rare occasions.

I think the slow motion thing is a hindsight thing probably. People can recall every detail of a serious occurrence that only took a couple of seconds to happen.

Bruthal · 13-10-2012 10:23am

vicwatson wrote: »

Poll ?

Probably not as bad as a tree...

im invisible · 13-10-2012 10:25am

Go for the tree, every time

af_thefragile · 13-10-2012 10:27am

https://www.youtube.com/watch?v=XbEU42UGXhE

Yeah...

BrianD3 · 13-10-2012 10:29am

So many variables involved eg type and age of car, type of tree and diameter of trunk, angle of impact and how much of your car overlaps the tree/other car.

Given the choice between hitting a tree head on or hitting an oncoming HGV head on at double the closing speed I'd pick the tree every time and try to hit it with the centre of the front of the car. If oncoming vehicle is a car it's not as clear cut. One disadvantage of hitting a car is the other driver might make a move which makes the angle unfavourable for you and maybe him as well

The Renault Laguna II was very solid when driven into a big tree at 55 mph impacting with the centre of the front of the car - however the forces on the occupants from the sudden stop may have caused death or serious injury

https://www.youtube.com/watch?v=2fLg8eQaPyE

The much older design Ford Sierra perfomed terribly when driven into a tree like barrier at a similar angle and speed

https://www.youtube.com/watch?v=zg9aHJl8MR8

The IIHS have recently started doing small overlap crash tests at 40 mph, if you hit a big tree with this overlap and speed the results would probably be reasoanly similar. The Lexus IS did badly in this test, your legs would be smashed and you'd be trapped in the car.

https://www.youtube.com/watch?v=wnK-TovPgrc

peasant · 13-10-2012 10:31am

Depends on whose fault it is that I suddenly find myself faced with an oncoming car:

- if it's mine I'd try for the tree
- if it isn't I'd take my chances with the crumple zones (especially as my van would most likely hump the oncoming car)

harsh, but true

ZETOR_IS_BETTER · 13-10-2012 10:43am

Mythbusters answered the question with regards impact speed and force on a car in a head on collision and hitting a wall head on

Basically makes no difference

CiniO · 13-10-2012 10:49am

Hal Decks wrote: »

What a ridiculous post!

That's not ridiculous post. That's actualy very wise question, as everyone might be forced to make that kind of choice some day and it's better to know what to choose.

CiniO · 13-10-2012 10:54am

If 2 cars each at 50km/h crash head on, assuming they are the same kind of cars (the same crumple zones, the same weight, etc) it will be equal effect as each of them hitting the wall at 50km/h.
Therefore if it was similar car to mine doing similar speed, I would choose to hit oncoming car head on that a tree. (just because it's way better to hit a wall than a tree).

But if there was big difference in weight or speed of vehicles (other vehicle much heavier or going much faster) I would probably choose to hit a tree.

F.e. If small car weighting 1 tonne doing 50km/h would hit another car doing the same speed but weigting 2 tonnes, effect would be like heavier car hit a wall at 33.3 km/h while lighter car like it would hit a wall at 66.6 km/h.
And this additionally means that twice the speed of accident, makes accident 4 times worse, as there is 4 times more energy to absorb.

af_thefragile · 13-10-2012 10:55am

CiniO wrote: »

If 2 cars each at 50km/h crash head on, assuming they are the same kind of cars (the same crumple zones, the same weight, etc) it will be equal effect as each of them hitting the wall at 50km/h.
Therefore if it was similar car to mine doing similar speed, I would choose to hit oncoming car head on that a tree. (just because it's way better to hit a wall than a tree).

But if there was big difference in weight or speed of vehicles (other vehicle much heavier or going much faster) I would probably choose to hit a tree.

F.e. If small car weighting 1 tonne doing 50km/h would hit another car doing the same speed but weigting 2 tonnes, effect would be like heavier car hit a wall at 33.3 km/h while lighter car like it would hit a wall at 66.6 km/h.
And this additionally means that twice the speed of accident, makes accident 4 times worse, as there is 4 times more energy to absorb.

So moral of the story is to buy a Hummer!!

AugustusMinimus · 13-10-2012 10:55am

robbie7730 wrote: »

In terms of reducing impact level, probably. But in reality avoiding hitting another car would be preferable.

If you have morals, you'll go for the tree.

Bruthal · 13-10-2012 10:58am

AugustusMinimus wrote: »

If you have morals, you'll go for the tree.

I thought thats what I said more or less:)

Although if it was the other drivers stupidity, maybe it would be better to hit them than watch them see you hit a tree, and get away with it.

thecomedian · 13-10-2012 11:06am

Your more than likely dead either way!

unkel · 13-10-2012 11:30am

Don't underestimate trees. Hitting even a small one is probably worse than hitting a solid concrete wall

BrianD3 · 13-10-2012 11:41am

unkel wrote: »

Don't underestimate trees. Hitting even a small one is probably worse than hitting a solid concrete wall

Yes, and trees with relatively small diameter (say 20 cm) but which are strong enough to not break when hit by a car might be the worst ones - due to the impact being concentrated on a small area of the car's structure. A huge tree with a 1 metre diameter trunk might be more forgiving.

Also, as bad as it is to hit a tree head on, hitting one side on is much worse.

Opel Omega vs pole, 98 km/h
http://www.youtube.com/watch?v=8QsKZWYYjfE#t=03m23s

af_thefragile · 13-10-2012 12:25pm

If only all cars were built like modern WRC cars.

https://www.youtube.com/watch?v=UDHwdSJZmAs

Both driver and co-driver escaped with only minor bruises!

Head on collision - choose a tree rather than an oncoming car ?

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