Originally posted by: carcynic on 31 May 12 @ 08:07 PM EST
This is one of many articles related to automotive safety here on CarCynic.com. To find other articles, just search for “safety” using the search box on the right.
Edit: 25 June 2012 – Added comments about safety glass.
One can take a quick glance at a Citroen 2CV, note that it has no airbags, and very lightweight construction, and come to the intuitive conclusion that it is not safe to drive on modern roads. Let’s add some automotive safety facts to our intuition, and see where the 2CV really stands.
First, in order to be fair and objective, we need to set some ground rules for the discussion.
Virtually everyone that lives in the industrialized world knows someone who has been involved in a serious automobile accident. If the person is a family member, or close friend, a car accident can be a very emotional event. Never the less, we must realize that a single event does not constitute a scientifically significant sample space. We need to put the anecdotal events and stories aside, and discuss facts and engineering.
Secondly, We must be fair and rational in cars we compare the Citroen 2CV against. If I somehow knew I was going to be involved in a collision with a bus, I’d rather be in an M1 Abrams tank than a Citroen 2CV — No question about it — but we must be a little less childish in our discussion.
Cars in 2 other classes make for fair comparisons: First, the 2CV is a small economy car. So for this discussion, comparing it with other small economy cars — even modern ones — will be considered fair game. Secondly, the 2CV is a classic, collectible car. Comparing it with most other antique collectible cars will also be considered fair, even if those cars are much larger and heavier than the 2CV. What is below assumes a rational comparison with other cars in either one of those 2 classes.
Part 1: Accident Avoidance
It may sound like a cliché, but it’s true: the best way to avoid injury or death in an accident is to avoid the accident. This is what is known as “Primary Safety“.
I was recently discussing this subject with a friend, and she insisted that if the driver of the other vehicle is drunk, there is nothing she can do to avoid an accident. I find this argument nonsensical. In the time you have taken to read this, there have been dozens of automobile accidents, but hundreds of alert drivers have swerved, braked, or somehow maneuvered to avoid a collision.
Part 1A: See and Be Seen
Before we can even hope to maneuver to avoid an accident, we have to be able to see potential dangers. Similarly, we want other drivers to see us. Day or night, vehicle lighting is fundamental to seeing and being seen.
If we take a quick look at the headlights of a 2CV, and then look at an American car of the same era, the headlights may initially appear much the same. They are not. Until 1983, US law required American cars to have sealed beam “lantern” headlights. Despite looking similar, the 2CV has glass headlamp assemblies with tungsten or halogen bulbs inside. Not only are those European lights far brighter, but they are also adjustable, so the driver can optimize visual range without blinding on-coming drivers. It’s a system that really is far superior to classic American cars, and equal to or better than most of the cars on US roads even today.
So a 2CV driver can see well at night, but how about being seen? Again, we need to look a little closer at vehicle lighting. Brake lights are one of the most important collision prevention features a car has [Link to be restored soon]. European cars work differently in this respect than classic American cars. If an older American car (prior to 1986) has it’s headlights on, it tail lights will also, of course, be illuminated. But here’s the problem — when the driver hits the brakes the taillights simply get brighter. No additional lights illuminate. Some US market cars and light trucks still operate this way. European cars have had separate brake lights since the 1960’s, and the 2CV is no exception. Except for very early models, separate lights illuminate when you hit the brakes. In later years, larger taillights were fitted, increasing safety even more.
The same basic concept applies to the turn signals (the British call them “indicators”). A classic American car, again uses the very same lights, actually blinking the stop lights OFF if the driver brakes and uses his turn signals simultaneously. Since 1968, the 2CV has had separate, yellow (amber) turn indicators. Two NHTSA (National Highway Traffic Safety Administration) studies show significant reductions in accidents on vehicles with amber turn lamps, as compared to those with red. The NHTSA studies are recent, but the European car makers knew it decades ago.
There are still additional ways that the 2CV’s lighting is better than most cars on American roads today. Starting about 1963, (depending on the original country it was sold in) 2CV’s may also have side turn indicators — uniquely located near the top of the “C” Pillar. Side indicators are required today every place in the world except North America, and again, there is real-world data that shows they are effective in preventing accidents. In this respect, the little 2CV is only 49 years ahead of it’s time.
So we see that 2CV’s (and to be fair, many other European cars) have far superior lighting to American cars that were made at the same time. But we don’t just drive by lights. Another meaning of visibility in automotive parlance refers to the driver being able to see what is outside the car, without parts of the car blocking or hiding another vehicle, pedestrian, or object. In other words — “Blind Spots”. As we go forward in the recent time line of automobile design, we can see that the “A” pillar — the part of the car’s structure on either side of the windshield, and at the front of the driver or front passenger’s side window — keeps getting thicker. On many modern cars, it can cut a fairly wide diagonal swath right though our field of view. Yes, a strong, thick “A” pillar does help protect us in the event of a roll-over, but roll-over accidents are actually quite rare in modern passenger cars. Furthermore, the “A” pillars must be thicker to give us the same — not more, structural protection that they did when windshields were less sloped. Of course, you can see where we are going (sorry about the pun) with this in respect to the 2CV. The 2CV has very narrow “A” pillars. 2CV’s basically do not have “blind spots”.
Part 1B: React — If you can.
It is generally acknowledged that European cars have better handling than American/Japanese/Korean cars. But what does “handling” mean? Simply put, handling means the ability of the car to go where the driver intends it to. Regardless of the driver’s skill level, better handling gives a better chance of maintaining control when attempting to avoid an accident. The unique, independent suspension of the 2CV may have been designed over half a century ago, but it is better than the suspension in some modern economy cars.
The same goes for the steering. A less massive object can change direction more readily. It’s very easy to demonstrate this by setting up some cones in a parking lot. A 2CV can easily be driven through a path that a Buick (for example) of the same vintage could never navigate successfully (at the same speed). The 2CV’s steering is quick and direct.
Steering and Suspension are important factors in vehicle handling, but there is also another — Traction. Just like some of the other aspects of the 2CV, it may seem counter-intuitive when we look at the narrow tires, but 2CV’s have excellent traction. Michelin (the famous French tire company) owned Citroen for much of the time the 2CV was made. Michelin was not about to let the 2CV, or any other Citroen, ruin it’s tire brand by having poor traction or handling.
Traction is not only important for swerving, but also for stopping. Remember our cones in the parking lot? Drive a 2CV at a constant speed, then hit the brakes at a per-determined spot. Place the cones in a line at the point where the 2CV comes to a stop. Now try the same thing — at the same speed — with that classic Buick. I can assure you that you are going to have some very smashed cones. It should also be noted that 2CV’s have front inboard mounted brakes — the same technology found on Formula 1 cars and exotic sports cars.
Part 2: What if the Worst Happens?:
OK, so we would like to avoid every accident, but even in a 2CV, the unavoidable is unavoidable. What if the worst happens, and you are actually in a collision while driving or riding in a Citroen 2CV? This is called “Secondary Safety“.
Part 2A: 3 Ways to get Hurt in an Accident:
Contrary to popular belief, injury to the occupants of a motor vehicle in an accident do not usually occur due to sudden deceleration. Notice I said usually — in extreme cases, the deceleration itself can be greater than what the human body can withstand. Such accidents, are (fortunately) the exception, not the norm, in on-road accidents.
It’s not 2 cars colliding that hurt people — It’s the other collision — the one between the occupants and the inside of the vehicle(s) that cause most injuries. Furthermore, this secondary impact is caused by 2 different aspects: In the first situation, the occupant moves within the car, and impacts or becomes impaled by vehicle components which remain in their correct location. In the second situation, the occupant is crushed or impaled by vehicle components that have moved from their normal locations.
So how does a very light car like the 2CV fair in each of the 2, more common, situations above?
If a car is hit by another vehicle, it will be abruptly pushed (accelerated) by the impact. (Remember that from a physics point of view, deceleration is just acceleration in the opposite direction, so we can use that terminology regardless of the direction of impact.) The mass of the vehicle that is struck will tend to oppose this sudden acceleration. This is the old adage that a 2CV will simply “scoot” or be “pushed out of the way”. However, the sudden movement of the car will attempt to impart a motion on the occupants. The occupants, however, have their own mass, and thus move with respect to the inside of the car. Given that your mass is the same no matter what car you are in, how much you move inside the vehicle is essentially dependent on the vehicle’s mass. You’ll feel less of the impact in a more massive vehicle. In this respect, a 2CV will fair worse than, for example, a Buick Roadmaster of the same vintage.
So how about that other form of injury — Injury from vehicle deformation? Well, we need another quick physics lesson here: No matter who hit who, the total energy is less when the mass of even one of the vehicles is less (for a given speed). Less energy means less deformation, and that means less chance of injury from being crushed or impaled due to vehicle distortion.
Here’s another way to think of it: Let’s take a simple case of a car crashing straight into a fixed (and strong) wall. Why doesn’t the vehicle simply stop or bounce off when the bumper first contacts the wall? That’s what happens if I push a toy car into a brick, so why doesn’t the same thing happen with a real car? It is the mass of the rest of the vehicle that continues to push toward the wall, causing the front to crush. A less massive vehicle will have less inertia to dissipate for a given speed of impact.
Now every automobile accident is different, and what exactly will happen to the occupants is impossible to predict, but we can see that there is some truth to the theory that 2CV’s are just “pushed out of the way” — It’s really just physics.
Part 3: Automobile Safety wasn’t Born Yesterday
The idea of preventing injury in motor vehicle accidents dates back to very shortly after the invention of the automobile itself. Despite its looks and absence of microprocessors, touchscreens, and pyrotechnics, the 2CV does have safety features. Citroen has been on the forefront of automotive design, including safety, for close to 100 years.
Here’s a Video produced in the 1970’s by Citroen showing some of their safety testing on 2CV’s, Dyane’s, GS’s and GSA’s, DS’s, and SM’s:
https://www.youtube.com/embed/43AgBuh9ot8
So-called “crumple zones” are one such technology that is not new. A crumple zone is an area of a car that is purposely weak or lightly constructed so that it deforms in an accident, thus dissipating energy. The remainder of the car then feels less deceleration force, with the intent of reducing the forms of injury mentioned above.
Look under the hood of a 2CV. There’s a lot that is not in there. The frame and body forward of the firewall are designed to bend to dissipate energy. Intuition might tell you that welding some heavy steel beams alongside the forward part of the chassis would make the car safer. You’d be dead wrong (Yeah, another bad pun). A more ridged frame would transmit more of the impact energy to the passenger compartment.
The front of a 2CV is also quite long for a small car. It is farther from the front bumper of a 2CV to the driver’s nose than it is in any one of a number of modern small cars.
See that flimsy hood? It’s light to allow the 2CV to have such a small engine, but it’s also designed to fold, and is wider than the “A” pillars. It’s designed so that it cannot come through the windshield in an accident.
As I mentioned, the topic of safety often comes up very quickly when discussing the 2CV and it’s relatives. It did so just recently when talking with a neighbor. He brought up the issue of safety glass, and assumed that European cars don’t (or at least didn’t) use safety (tempered and/or laminated) glass windows and windshields. As a generalization, his assumption is false. Whether or not a particular 2CV or derivative has safety glass depends on it’s year of manufacture, and the country it was originally sold in. Most later models have safety glass all around. It’s also important to note that all 2CV glass is flat, so a glass shop could simply make laminated glass windows using the original ones as a template.
While you have the hood open, take a look at the firewall. Why is the bottom part of the firewall curved like that? It almost looks like the front of a barge or flat-bottom boat. Just like the front of a boat is designed to ride up over waves, the passenger compartment is designed to ride up over the engine and gearbox in a serious frontal impact.
Since we are looking under hoods, look at a typical American car of the same vintage. You will see a long shaft running from the firewall to a steering box in front of the front wheels. In many cars, the steering shaft was pointed exactly at the driver’s chest, throat or face. In later years, they got the idea to include joints where it can bend, but many people have died from being impaled by the steering column. Now look at the same area under the hood of a 2CV. The shaft simply isn’t there. It is much more vertical, and leads to a steering rack well behind the front wheels. Simply put, there is no reasonable scenario in which you are going to be impaled by the 2CV’s steering shaft. In fact, the steering rack marks the end of the crumple zone and is part of the rigid protection of the passenger cabin.
Lastly, that funky one-spoke steering wheel that is seen on later 2CV’s and on other Citroen models is also a safety feature. It is designed to bend if your head, face or nose hits it. Essentially, it is designed to perform the same function as an airbag.
Speaking of Airbags…
Part 4: Some of what the Citroen 2CV Lacks Makes it Safer.
Overall, airbag systems do provide a net reduction in injuries, as compared to a similarly designed vehicle that had no airbag(s). But I still don’t think they are the safety panacea that the automotive marketing machine has made them out to be. Here’s a few airbag facts:
Airbags have killed children and small adults. Modern airbag systems are smarter about both when to deploy the airbag, and how much force it deploys with, but there is still a potential for significant injury or death solely from the airbag.
Even newer generations of airbag technology deploy with great speed and force. Look carefully when you see videos of airbag deployments. They are almost always shown in slow-motion. If you have ever experienced an airbag deployment yourself, or seen full speed video of an airbag deployment, it is quite frightening. (This can be seen at approx. 3:46 in the above video — the airbag deployment is shown only in slow-motion.)
Once deployed, an airbag makes a secondary collision or impact far more dangerous. When an airbag deploys, it destroys the padding on the steering wheel (or door, or A-pillar for side impact systems) and then rapidly deflates, leaving structure, metal edges, bolt heads, and other interior components with no padding. In modern cars, multiple airbags can deploy simultaneously, leaving the occupants vulnerable to additional impacts from other directions. Secondary impacts and multi-car pileups do occur in on-road accidents. This is one reason that race cars don’t have airbags.
Not only do airbags leave structure and sharp edges exposed in a secondary accident, they can actually cause them. It is impossible to keep your hands on the steering wheel when an airbag deploys. In addition, you will be temporarily blinded by either the airbag itself, or the powder used to pack it. If you are still moving, you are completely unable to control the vehicle. I want to be clear on this, and dispel any myths. Even modern airbags DO NOT and CANNOT re-inflate in subsequent impacts.
Inadvertent airbag deployment has always been a rare occurrence. As automotive technology has progressed, erroneous or spontaneous airbag deployment has become even more infrequent. However, there is still a small, but persistent number of vehicle recalls related to false deployments.
Not only have there been several recent cases of automotive software programming issues, but the possibility of intentional hacking has recently been raised with respect to modern, interconnected automotive systems. We haven’t gotten to the day when a hacker with a laptop and a hi-gain bluetooth antenna can stand on a freeway overpass and cause your airbag to deploy, but there is enough evidence of this possibility that I can write this without it being fear-mongering.
So if airbags are so bad, why do we have them in cars? It’s simple marketing. Congress wanted to make laws that forced the automotive manufactures to build safer cars. The automotive manufactures did not want the cost of the cars to increase, or to loose money on each car made. Everybody wanted cars to use less fuel, so this ruled out more structure or things like roll cages. Nobody wanted to be inconvenienced by 5 point harnesses, helmets or other “intrusive” safety devices. The airbag was relatively cheap to produce, lightweight, and almost totally hidden until deployed. As long as you have an accident exactly like the ones the NTSB simulates, airbags actually fit all the requirements pretty well.
I am not telling you to go rip the airbags out of your current car. I am only saying that the fact that the Citroen 2CV lacks them may not be all bad.
This article will continue in future postings.
Part 5 Will cover Safety Features that your mechanic or restorer can add to your Citroen 2CV.
Part 6 Will cover Some Suggestions about driving a 2CV.
Edits:
05 June 2012 — Grammar
Additional Reading:
Driving and the Integral of Danger
Did you know that US Air Bags are more Dangerous than European ones?[Links to be restored soon]
Disclaimer: This article does not suggest that you purchase, drive, or ride in any particular vehicle, or that you refrain from doing any of those things. It attempts to objectively convey information about automotive engineering topics only. Ultimately you are responsible for any use of this information, or any actions you take. Always drive safely.
Originally posted by: carcynic on 31 May 12 @ 08:07 PM EST
