Do Sedans survive rear-ended accidents better?

[krish82]

Originally Posted by krish82

Hi All,

10 days before my daughters birth, An auto came and smashed my car from behind while i was standing in Traffic signal, he came out of no where, people from the auto were thrown out and injured. Thankfully my wife was not in the car. My Optra rear bumper,tail light and little part of right hand side body took the dent, The bill was 30 k for the repairs and i had to pay 9k rest the insurance. Auto fellow did not have any insurance, police fellow suggested i claim for him too, what the hell it was not my fault, i knew police are such a waste and left the scene saying i will take care of my car. But this accident has created a bad psychological impression on my mind. With my new born daughter and family i am now becoming too much concerned about safety, and the thread accidents in india makes me more insecure, not sure if that thread really helps, because when an accident happens its out of no where all of a sudden. i was just thinking what if it was not an auto but a truck, the damage would have been more, So since we know the fact that heavier vehicles are damaged less in accidents when thay crash with smaller ones, doesn't a good heavy sedan take impacts well compared to small cars no matter with how many airbags.

But all i was thinking that if it was a small car without a boot the damage would have been more, also the rear glass may have shattered. I felt Optra's well built took the impact nicely and since sedans have larger boot and crumple zone it should take impacts better than the smaller cars.

Hey but my both the cars Optra and Getz has no Airbag or ABS. I am not using my Getz for all doctor visits. I know with time i will forget the incident. But i really feel that than buying a new car with ABS / Airbag if not in budget we can go for a second hand sedan with these feature that may handle crashes better. Some cars with airbags abs like elantra i have seen in dead cheap prices. I may be wrong though.

Uploading some Snaps after the accident. Although may not look much, but the speed at which the auto had hit was more, may be more than 40 kmph, just an assumption, after hitting my car it still couldn't stop and rear ended a alto. i don't have the snaps of the auto, but it got bent totally.

Total Damage : Rs 29000
Insurance : Rs 20000
I Paid: Rs 8800
Garage: Sundaram motors chennai, they have done an excellent job, doesn't look if it had happened at all. I am yet to take snaps after the accident.

[libranof1987]

Originally Posted by GTO

Here's some food for thought : Honda says it costs more to build the Jazz body / monocoque than the City. Why? Simply because of the reinforcements that the hatch area is given. The primary reason is safety, the second to support the weight & operation of the actual hatch.

Would this be an answer for my question in an earlier post?

Originally Posted by libranof1987

A question : Are crumple zones better designed to absorb hits in sedans w.r.t hatches?

If yes, how so?

[ghodlur]

Originally Posted by libranof1987

If yes, how so?

Just to reply to your question here's the quote which I googled. Hope this helps.

Source : SmartUSA

Of course, it's easy to build crumple zones into a large vehicle with plenty of room to crumple before the passenger compartment is impacted. Designing crumple zones into small vehicles takes some creativity. A good example is the smart fortwo, an extremely small
and efficient vehicle. The driver and passenger are enclosed in the tridion safety cell, a steel framework with excellent rigidity for its size. The geometry is designed to distribute impacts across the entire frame. At the front and rear of the smart fortwo are what smart calls crash boxes. These are small steel frameworks that collapse and crumple to absorb impacts. Because the crash boxes are so small, other impact-absorbing features have been used to supplement them. For example, the transmission can act as a shock absorber in the event of a front-end collision. The short wheelbase of the fortwo means almost any impact will involve the tires, wheels and suspension. These components have been designed to deform, break away or rebound, helping absorb even more kinetic energy during an impact source

[libranof1987]

^^ As per GTO's post, the Jazz chasis costs more than that of City.

And the article says it is easier to have crumple zones in a sedan (obviously).

So, how do they make it up in a hatch? Stronger material?

[vb-san]

Originally Posted by GTO

Here's some food for thought : Honda says it costs more to build the Jazz body / monocoque than the City. Why? Simply because of the reinforcements that the hatch area is given. The primary reason is safety, the second to support the weight & operation of the actual hatch.

That’s right.
Also, I remember Mustang.101 mentioning the same in the New Fiesta thread (that the Fiesta hatchback has higher manufacturing cost compared to the sedan).

[csentil]

I don't know how many of you'll have sat in a car when its been impacted by a Canter/Eicher at around 60 kmph. I have The Eicher braked into my Civic while I was waiting at a signal. It was a full rear impact and not a side on hit. The driver was drunk!

The impact was such that my Civic was sandwiched between the Eicher and the Innova which was in the front. The Innova infact moved enough to rear end a Swift. Such was the impact of the collision.

If the folks at the rear had not been wearing seatbelts they would have been thrown forward onto the front seat or my head or whatever and would have definitely suffered serious injuries. So it is wrong to assume that in a rear ended collision, seat belts are of no use. My friends who were seated behind were thankful that I insisted that they wear seatbelts.

All of us walked out without a scratch. My Civic's rear was totally gone and it burnt a big hole in my pocket inspite of insurance.

I shudder to think if it had been a small hatchback which has poor safety ratings (there are some that ply our Indian roads).

I had posted the photos in the Accidents thread earlier.

[vivekiny2k]

I had to go back to the first page to see what the discussion was about. better than front end collision, or better than a hatch?

Obviously sedan's have more length to crumple in front and back. the compacts have to be designed much more better to provide that level of safety. Not impossible, but difficult and costly.

About sea belts being useless in rear end collision, once a car has been hit, the occupants can go flying in ANY direction depending upon the next force that brings the car to a halt. seat belt will help keeping one in seat.

Originally Posted by libranof1987

So, how do they make it up in a hatch? Stronger material?

And design. Look for some crash tests on mini cooper and smart.

[Daewood]

Originally Posted by vivekiny2k

Obviously sedan's have more length to crumple in front and back.

Two similar sedan and hatch (fiesta hatch & sedan, Polo & Vento, etc) always have the same length at the front. So can't say a similar sedan has more length to crumple in a frontal collision. If you are comparing a smaller hatch and larger sedan obviously the sedan has more crumple length.

Rear end collision is very different from a frontal one, since here one car is stationary and hence acceleration is zero for that.
a) If a small vehicle with less mass and speed hits from behind, the bumpers /hatch/boot take some of the force, and and the rest of the force is used to move the car forward.
b)If the same car is hit by a larger vehicle with more force the same force as above is needed for the destruction to the rear end and the rest of the excessive force will move the car forward in a much more speedier way.

The major difference between both cases is the speed with which the car is pushed forward, and in such scenarios it's the neck restraint, seat design and rear bumpers that play a major role in the extent of injury.

[Dr.D]

Hey krish82, i really feel your pain thambi ! I have to state that there is nothing worse than a chennai auto/auto driver on the planet .

Getting back to business.. the hatch or the sedan. Well most of the sedans share the same chassis as the hatch, example - swift - dezire, polo - vento, golf - jetta, jazz - city, ect
the modern concept in safety design since the late fifties and early sixties took leave from the rigid car design as it incorporated crumple zones and rigid cabin design paradigm. -----------------
So basically what we have here is

Front crumple zone----Rigid cabin-------Rear crumple zone

Now, a sedan bases on the same chassis as the hatch rear ended will not have the rear boot space volume offering any significant benefits over its hatch sibling. in fact I would bet a non reinforced boot is more prone to damage than the reinforced rear of the hatch back.

Now now, lets not get carried way and start boasting hatch back strength to our friends. It again depends on the the hatch size and its fabrication quality.
what i mean is you will be safer rear ended in a i20 than a i10. On the other hand the Polo and vento rear ended my not give very different results when it comes to passenger safety.