The Crumple that Saves
I hate travelling in a public transport via road in Nigeria. I know hate may be a strong word. But a tour of any of my nation's major roads may convince you that I may be right for using such a strong language- the carcasses of once upon a time vehicles that litter the roadside is a macabre grim reminder that road is not as safe as it ought to be.
According to the first quarter report of the Nigeria Federal Road Safety Corps (FRSC) for 2018, we have 8672 victims of road traffic accident that was injured in the first quarter of 2017, and 8466 wounded in the first quarter of 2018 out of the 18230 and 18116 accidents that occurred in the first quarters of 2017 and 2018. These are the lucky ones as the number of fatalities are more than 10% of the injured; 1466 and 1292 for the first quarter of 2017 and 2018 respectively. That means we have an average daily fatality of about 15 per day for both year's first quarter. That is an incredible amount of people dying.
Part of the problem why we have this unusually may be due to bad roads and most importantly the vehicle of choice for most of our public transport sector. The transporters seem to favour Mitsubishi L300 buses and likes which has poor safety features. The Australian New Car Assessment Program (ANCAP), an independent safety information provider rated the bus 8.49 out of 37, a one-star rating for the poor performance in safety.
You may not have to take their word for it, but this collision test video shows you what will happen in the event of a crash. The vehicle, upon lacking seat belt has a terrible crumple zone.
Before we delve into what a crumple zone is, it is imperative that we check the history of it. The name Béla Barényi may not ring a bell like that of fellow inventors like Wright Brothers; the aeroplane inventors or Thomas Edison famous for his works in inventing the electric bulb and other fantastic invention. Barényi, the Austro-Hungarian Mechanical and Electrical Engineer who later worked for Mercedes Benz who has up to 2000 patents which is twice that of Edison may be the guy to make the difference between walking out of a crash or having a loved one ID you in a morgue.
Barényi Béla with a Mercedes Benz model in 1939. Image credits: By MercedesPublic Domain from Wikipedia Commons, Link]
In 1951 Béla Barényi walked out of the patent office with registered patent DBP 854.157 generally referred to as the crumple zone patent.
The crumple zone technology makes a car crumple as it cushions/absorbs the impact created when a car suddenly decelerates due to a collision. You can better understand how this works if you imagine while running and you unintentionally ran into a brick wall versus when you ran into a wall padded with a mattress at the same speed. You will feel more of the impact in the former than the latter due to the time difference between deceleration.
This behaviour occurs thanks to the fundamental laws of physics which is beautifully expressed by Newton Second Law of motion where Force F is equal to the product of mass and, i.e. F= ma.
We may already know that acceleration (a) gauges the change of velocity (∆v) which has a relationship with the mass of the object known as momentum which is expressed as m∆v. If an object has momentum, it means it will be difficult to stop it. The difficulty increases with the increase of momentum. From the formula, you can already relate that the more the mass of the object, the bigger it's momentum.
Since F= ma
and a = ∆v/t
Therefore F= m∆v/t or F∆t= m∆v
The product Ft is known as the impulse. Impulse, on the other hand, gives the relationship between the change that occurs in the momentum of an object. Looking at its formula, ft, it shows the importance of time (t) on the force that acts on an object as its momentum changes. The shorter the time of a crash, as witnessed by a sprinting crashing into a wall, the higher the damage to the body. But a sprinter that crashed into a wall padded with a mattress experiences more time between the time of impact and body coming to rest.
This Saab vehicle shows the crumple zone in yellow with the rigid passenger compartment in red. Image credits: By MarcusrooPublic Domain from Wikipedia Commons, Link]
The crumple zone was designed to reduce the severity of injury by distributing the force of collision to the vehicle through decreasing the stopping time of the car hence lessening its impulse which reduces the impact force of the crash. The passenger compartment of the car is rigid, while the crumple zone "buys more time" via a lengthening of stoppage time thereby reducing the g-force felt due to the very fast deceleration due to the force of inertia-the tendency to continue in the direction of motion.
The bumpers positioned in the front and rear of the vehicle serves the same protection, with some cars having reinforced steek sides which comes in useful in the event of a side-on collision.
Though absorption of impact through the redirection of it is a great feature, some vehicles like the Mitshibusi L300 series crumple up the point of passengers and drivers sitting in the front if there was a frontal collision.
The bulk of the commercial passenger transportation in Nigeria uses Mitsibushi Mini Bus with inferior safety features or the Toyota Hiace buses, a bus currently banned in the USA after crash testing find it unable to yield the much-needed crumple zone for the safety of passengers.
- FRSC 2018 First Quarter Report
- Mitsubishi Express Safety Rating
- Béla Barényi, the lifesaver
- How Crumple Zones Work
- Why doesn't Toyota bring the HiAce to the US?
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