Car safety

[Adrian E]

Here's an interesting video for comparison (NOTE THAT THE TITLE IS INCORRECT AND IT'S AN A4) - the one above is into a solid concrete block (notice how little intrusion there is into the passenger compartment)

https://www.youtube.com/watch?v=o0ZAzVSxabU

This one is into an offset deformable barrier (honeycomb of aluminium which represents the stiffness of a 'real car' of similar design) which can be seen post-impact at about 2.5 mins in.

What you do not want to see is the deformation of the A pillar you see in this video - that's a structural integrity failure, which means the energy is no longer being managed by the crash structures.

[moltuae]

Originally Posted by Adrian E

Bigger does generally equate to better in an impact, but there's always something bigger and heavier with which you can impact! Think HGV or bridge parapet as examples. EuroNCAP themselves say you should only use their ratings to compare across similar sized vehicles, as the offset deformable barrier test replicates an impact with an identical vehicle, which is far more relevant in most cases than the solid concrete block of old which resulted in vehicles that passed that requirement falling to bits when confronted by another vehicle with a mix of solid and soft parts to interact with. You can make a car very stiff and limit intrusion that way, but the occupants will then experience higher HIC readings and other biomechanical injuries that will result in a less bent car, but very poorly occupants. Think original Smart car as an example, where there simply isn't space to do anything other than make it really stiff.

That is the problem with EuroNCAP tests, driving into an immovable concrete block doesn't really provide any indication of how the vehicle will fare in a head-on collision, except, as you say, with a vehicle of identical weight.

I don't have the statistics, but I would image a lot of the more severe or fatal accidents are head-on. Motorway design is such that it's quite difficult to hit something as immovable as a bridge or concrete block at high speed; side-on collisions with barriers or traffic going in the same direction are more likely. By contrast, on A roads that have no central barrier, 2 vehicles travelling in opposite directions at just 50mph will have a combined impact speed of 100mph. This of course isn't equivalent to hitting an immovable object at 100mph (rather, hitting a stationary vehicle at 100mph), but the forces worsen greatly for the lighter of the two vehicles.

Also, as I said earlier, there's the matter of being in control of ones own destiny. If I'm a good driver I can most likely avoid a lot of EuroNCAP type accidents. The same can't be said for potentially fatal head-on collisions, for which you may get little time to react.

Of course by reasoning that bigger/heavier is better, I should ideally drive a tank or a truck, but of course there's a practicality compromise to make. For me an 8 is a very good compromise, especially considering the vehicle I'm more likely to meet head-on around a blind-bend is probably going to be a small one, driven by an inexperienced, over-enthusiastic driver. Vehicles larger/heavier than my 8 are probably not just less likely to be on the wrong side of the road but also likely to be taller (and therefore visible sooner) and travelling more slowly. In which case, the fact that the 8 is still light enough to be fast and agile, would hopefully help to get me out of trouble.

[Adrian E]

Originally Posted by moltuae

That is the problem with EuroNCAP tests, driving into an immovable concrete block doesn't really provide any indication of how the vehicle will fare in a head-on collision, except, as you say, with a vehicle of identical weight.

The concrete block tests were phased out years ago for regulatory purposes (think Sierra era) - after EuroNCAP moved to offset deformable the regulatory test followed, but at a lower speed and with a simple pass/fail, rather than a scored ranking.

Any of the impact types we talk about involving motorways are likely to be so severe as to be unlikely to be survivable, whether it's hitting a heavy object or being struck head on, just due to the speeds involved before deceleration commences.

[Architex_mA8tey]

Originally Posted by Adrian E

The concrete block tests were phased out years ago for regulatory purposes (think Sierra era) - after EuroNCAP moved to offset deformable the regulatory test followed, but at a lower speed and with a simple pass/fail, rather than a scored ranking.

Any of the impact types we talk about involving motorways are likely to be so severe as to be unlikely to be survivable, whether it's hitting a heavy object or being struck head on, just due to the speeds involved before deceleration commences.

Whilst we are talking about hitting solid objects Adrian - do you have any views / comments on the deform-able steel central barriers on motorways being replaced by solid concrete lumps? surely this is a cost thing rather than a safety thing as the deform-able ones help to absorb energy??

[moltuae]

Originally Posted by Adrian E

The concrete block tests were phased out years ago for regulatory purposes (think Sierra era) - after EuroNCAP moved to offset deformable the regulatory test followed, but at a lower speed and with a simple pass/fail, rather than a scored ranking.

I wasn't aware of that. But either way, I'd prefer to see head-on crash tests (and not just because they'd be more fun to watch! ). It would be good to see more real-world scenario tests performed (eg, cars head-on of equal size/weight, small vs large cars, medium vs large, etc, etc).

It would also be interesting to see statistics of real collisions in EuroNCAP tested vehicles to see whether the injuries and fatalities data aligns with the test results. My guess is there will be a loose correlation at best.

[tintin]

Originally Posted by Adrian E

With the A8 not being a big seller in relative terms it doesn't surprise me that Audi wouldn't choose to self-fund a test, if the majority of their customer base makes the purchasing choice on the assumption the car is safe due to its size, and they'd be better off spending their money in another area of marketing.

Wouldn't Audi want to know anyway, just for corporate peace of mind - or do they run their own more rigorous crash safety tests internally which would make that unnecessary? I thought the D4 sold more than the D3, which in turn sold more than the D2, so it seems a bit illogical to crash test the D2 but not later models - unless, as you've said, they see this a marketing rather than safety exercise?

[paulrstaylor]

Originally Posted by Architex_mA8tey

Whilst we are talking about hitting solid objects Adrian - do you have any views / comments on the deform-able steel central barriers on motorways being replaced by solid concrete lumps? surely this is a cost thing rather than a safety thing as the deform-able ones help to absorb energy??

I think it was more of a stopping vehicles (including HGVs) crossing into opposing traffic, which is not a bad idea.

Given it is a continuous pour any impact is likely to be a "glancing blow" and a "head on" should be nigh on impossible? Add in the advances in car safety (i.e. crumple zones) and I think it makes a lot of sense - but suspect it is all a balancing act

[HPsauce]

Originally Posted by Architex_mA8tey

Whilst we are talking about hitting solid objects Adrian - do you have any views / comments on the deform-able steel central barriers on motorways being replaced by solid concrete lumps? surely this is a cost thing rather than a safety thing as the deform-able ones help to absorb energy??

I think the solid concrete barriers are designed to stop almost anything getting across to the other carriageway and so avoid the worst head-on colliions; pretty sure I read an article explaining the logic several years ago when they started to appear.

[moltuae]

Originally Posted by Architex_mA8tey

Whilst we are talking about hitting solid objects Adrian - do you have any views / comments on the deform-able steel central barriers on motorways being replaced by solid concrete lumps? surely this is a cost thing rather than a safety thing as the deform-able ones help to absorb energy??

Do you mean the posts for the steel rope barriers? I thought they were usually made of steel too. Or are you referring to something else?

I know that the rope barriers, despite their flimsy appearance, tend to perform much better than the conventional steel barriers:

https://www.youtube.com/watch?v=R8rzbsuEfVY

[paulrstaylor]

http://www.roadtraffic-technology.co.../feature67206/