[Daewood]

Originally Posted by Gooney

I totally agree to the theory of motion you used in your argument (the intensity of a rear impact is the same irrespective of a sedan or a hatchback). However, in real life situations, it is not so. A sedan takes a rear impact much better than a hatchback, irrespective of passive safety features present or absent.

The injury to a rear seat passenger is not just by proximity to the rear end of the car. It also depends on many other factors like seat design, rear head restraints, etc. If you see the scores of the whiplash test in EURONCAP many hatchbacks like Swift, Polo, i20, Beat, etc have performed better than sedans like mercedez-C class!!!
http://www.euroncap.com/whiplash.aspx

[lucifer1881]

First of all, when rear-ended seat belts are useless. Airbags will not be deployed either. One of the worst situations is to be in a high-speed crash where a vehicle rams into another from the behind. The passengers in the vehicle which is rear-ended suffer most injuries.

Your thread title says "Do Sedan Cars Survive Crashes better!". Don't you actually mean to ask if occupants of sedan cars survive crashes better?

From what I understand, purely from a vehicle-surviving-a-crash point of view, a body-on-chassis design will survive a crash better than a monocoque design. For example, if the A-pillar of a car needs to be replaced. It is much more difficult to do this on a monocoque without impacting its structural integrity. In a body-on-chassis design, it is a lot easier.

Coming to people in cars. This depends purely on your luck. No two crashes are alike. There have been instances where seat belts have caused more serious injuries or even death. That does not mean seat belts should not be used. Of course they save lives. On highways, I ensure all occupants in my car wear seat belts.

Similarly, it does not matter whether you are in a similar-safety-rated sedan or hatch. The nature of the impact determines everything. That said, I would assume you would be much safer in a Toyota Land Cruiser compared to a Toyota Camry for the same kind of crash. This is purely conjecture and I would like someone to throw more light on it.

[Gooney]

Originally Posted by Daewood

The injury to a rear seat passenger is not just by proximity to the rear end of the car. It depends on many other factors like seat design, rear head restraints, etc. If you see the scores of the whiplash test in EURONCAP many hatchbacks like i20, Beat, etc have performed better than sedans like mercedez-C class!!!

Yes you do have a point; but like I mentioned in my previous post, all safety features being the same, sedans survive rear collisions better. (And that is why I compared the Swift and the DZire).

[breezydrive]

A simple solution to reduce rear end impact while one is stationary at signals/ road side parking is to park in neutral w/o pulling up the hand brake!

[julupani]

Originally Posted by Gooney

I totally agree to the theory of motion you used in your argument (the intensity of a rear impact is the same irrespective of a sedan or a hatchback). However, in real life situations, it is not so. A sedan takes a rear impact much better than a hatchback, irrespective of passive safety features present or absent. To illustrate, I have attached pictures posted by laxmanrk in the Accidents in India thread. See for yourself, if it had been a Swift instead of the Dzire, the occupants in the rear seats would have definitely suffered more injury.

No, the Swift would do equally well.

If you read my experiment analogy, and read what happens in case one, I dont say that no compression occurs. I said, only after a certain amount of compression, does the force get transmitted.

In the above accident, once the above compression occured, any further energy would be converted to kinetic energy of the car. That is because the passenger compartment is designed not to compress, but to transmit the force through. This would have happened in the case of the hatch too, just without so much crumpling. Instead almost all the energy would have been converted to extra kinetic energy and a bigger increase in speed of the hatch would be noticed after the crash.

Its just a question of which car can crumple more, before the force can get transmitted through. Replace the tennis balls in my analogy with ivory balls, and you will have almost no compression at all.

But remember in both cases, all the passengers experience is a massive jolt, but the passenger compartment would maintain its integrity equally well. But if we had better overall structural design in a hatchback, it would end up performing better.

That's why I maintain, a better design is more important than being a sedan or a hatchback.

[Daewood]

Originally Posted by breezydrive

A simple solution to reduce rear end impact while one is stationary at signals/ road side parking is to park in neutral w/o pulling up the hand brake!

That would save the rear end of the car from much damage, but the passengers will not be safe, as they will get pushed forward faster, which in turn will result in damage to spine, etc
which is the most common injury in a rear collision.

Originally Posted by julupani

That's why I maintain, a better design is more important than being a sedan or a hatchback.

+1

[sids911]

Originally Posted by lucifer1881

First of all, when rear-ended seat belts are useless.

Whoa! Please dont even write this on public forums, people might take it seriously!

In a severe whiplash caused by rear-end collisions - seat belts protect from chest injuries which can be fatal. These chest injuries are caused by hitting the steering wheel for the driver.

And the front passengers might get thrown out of the front window if they arent wearing seat belts on a severe rear collision impact.

Also, the head/neck restraints play a pivotal role in case of a whiplash caused by rear-ending!

Basically seat belts;

(a) prevent ejection from the auto,
(b) allow a more controlled deceleration during the initial phase of the collision,
and (C) reduce the severity of impact between the wearer and the car interior.

HTH

[vibbs]

This might be but since the discussion has touched on to the importance of rear seat belts, i ll share links of 2 videos which may remove any confusion

‪Rear Passenger Seatbelt‬‏ - YouTube

‪Rear Passenger Seatbelt - Second Video‬‏ - YouTube

PS: Mods may delete the post if not really warranted

[vb-saan]

Good thread. Thanks Krish for starting this discussion.

This is one reason I am looking to change my current Ford Ikon. A fairly sturdy car, but with better roads and increasing highway speeds, I feel car with basic safety features (ABS, Airbags etc.) is a necessity.

Originally Posted by julupani

That's why I maintain, a better design is more important than being a sedan or a hatchback.

Originally Posted by ajmat

The best protection is to ensure your child is secured by a belt. MY daughter has always used a belt and now at 13 yrs, it is a habit!

Completely agree with the above two statements. And someone mentioned that seatbelts are of no use when rear-ended. That’s so wrong.

Do we have any reference database on the safety of cars sold in India? Some manufacturers advertise Euro NCAP rating, but IMHO it’s quite invalid for the cars sold in India (or maybe applicable only for the top end variant). And I am not sure if its right to generalize based on the type of the car – sedan v/s hatchback v/s SUV. I maybe wrong here, but just giving an example - if the occupants are properly belted in, I feel a Skoda Fabia Elegance will offer more safety than a Swift Dzire. I feel manufacturers own safety standards and safety history plays a key role.

[dhanushs]

As for if sedans are safer.

Frontal Impact: This entirely depends on the design, equipment and quality. A hatch can fair similar to a sedan.

Side Imact: This is same as frontal impact, and depends on the design of the car. A well designed/equipped hatch is any time better than a poorly designed/equipped sedan.

Roll over: Same as the above. Design, equipment and quality take priority over the type of car.

Rear impact: Now, statistically , only 5% of total accidents involve fatal rear endings. Out of which, majority of harm/deaths are caused by whiplash, which does not depend on the type of body the car has, but solely depends on the design of the seat/recline angle/head restrains.


EDIT: Oh.. and, seat belts are useful for any kind of impact. All safety designs/equipments are made on the assumption that the passengers are wearing seatbelts. Please DO NOT DRIVE without wearing them.


Good Whiplash Design


Medium Whiplash Design


Poor Whiplash Design


Other than these factors, I guess sedans, SUV's or in general the heavy vehicle has an added advantage of mass. Which is not much, and can be overcome by sensible design. Unless a Truck is ramming into a hatch.


Image Source: HOME | Euro NCAP - For safer cars crash test safety rating

[lucifer1881]

Originally Posted by sids911

Whoa! Please dont even write this on public forums, people might take it seriously!

Originally Posted by dhanushs

EDIT: Oh.. and, seat belts are useful for any kind of impact. All safety designs/equipments are made on the assumption that the passengers are wearing seatbelts.

I will respectfully disagree with the above. Seat belts do not work when rear-ended.

A front collision is analogous to very hard braking. The inertia of motion of your body makes your torso move forward and hit the dash or steering or the front seats, depending on where you are sitting.

A rear collision is analogous to very hard acceleration. Your body is at rest. Suddenly the car movies forward. Your body seems to be pushed back into the seat further, the same way you feel pushed back into the seat when you apply a sudden surge of power to the wheels.

Whiplash depends on the design of the headrests. A poorly designed headrest will cause whiplash, irrespective of whether it is a frontal collision or a rear one.

Warning: I am NOT in any way saying that seat belts are useless. They save lives. Even in a rear collision, there is no harm caused by having them on. But not having them on in a frontal collision may lead to loss of life or limb. The above post is only a technical discussion on the usefulness of seat belts in rear collisions. There are many types of collisions possible. Wear your seat belts at all times.

[vibbs]

Originally Posted by lucifer1881

First of all, when rear-ended seat belts are useless.

Sorry there was a misunderstanding. I somehow happened to read the quoted line as rear seat belts are useless. Thats what made me post the below quoted post. And I m not able to edit the post now. The videos still hold good though.

Originally Posted by vibbs

This might be but since the discussion has touched on to the importance of rear seat belts, i ll share links of 2 videos which may remove any confusion

[dhanushs]

Originally Posted by lucifer1881

A rear collision is analogous to very hard acceleration. Your body is at rest. Suddenly the car movies forward. Your body seems to be pushed back into the seat further

Agree.

What happens after that?

[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.

[Dr.D]

Wishing health and happiness for all I vote for the bulldozer .

Now, seriously the whole idea of which is safer the hatch or the sedan is like questioning can a super heavy weight boxer compete with a middle weight world champion and the answer is no ! look nothing is bullet proof and with his speed and skill he will murder the less talented heavier fighter.

Talking cars, many smaller cars have been found to be safer than larger sedans and saloons when crashed at the same speed.(depends on the test) It does not matter how big it is but how well made and designed it is !!!!

I BET THE F-1 CARS ARE MUCH safer than our tough looking friend the SUV.(don't get tempted to take my bet. they are safer)
Abs,air bags,esp,e.c.t.. yes these are essential and the government should promote their usage in cars by slashing taxes.

Before i forget lets get one more thing straight Ahemm clearing my throat, the bolt on chassis design is not safer than the uni body design !!! in fact most recent comparisons have shown the bolt on chassis bend and flex to a higher degree invading the passenger cabin. The modern uni-body is designed to transfer force from the impact zone to rest of the body preserving the integrity of the cabin.

Conclusion:- think of the type of cars you are most likely to encounter, their average speed and choose accordingly. To explain better
1)if your house is on the highway and you encounter lots of heavy vehicles buy a MPV or a crossroader.
2) In city a more nimble zippy car will do
3) If one is stationed in a war torn territory with lots of bullets wiz-zing by then invest in the T-95 battle tank