[SJD@NewDelhi]

An attempt at explaining the reason behind the Taj expressway accidents:

One of the most common news concerning the newly constructed Taj Expressway are car tyres getting punctured, due to which many lives have been lost. The question arose in my mind as to why such incidents are happening so frequently in one of the most modern roadway in the country.

The cause behind majority of the accidents were the same - tyres getting punctured while on high speed (which is common in the expressway). So what is the actual reason behind these occurrences, when it is not that someone comes every night and sprinkles nail on the tar

We got the BMW X1 SUV from one of our team-members for the test. Please keep in mind, the original focus would be on the tyres. First, we checked the pressure of the tyres and set it to 25 PSI, in accordance with the international standards (cars in all developed countries maintain this pressure level diligently while most of the people in our country are either not aware of this or maintain pressure level as high as 35-45 PSI in order to get higher fuel economy). Now lets get on with the test at hand.

Next, we left for the Taj expressay from Noida. We maintained high speeds. After driving the car in this manner for about 2 hours, we reached the periphery of Agra. On checking the tyre pressure before Agra, we were presented with startling results. The tyre pressure was 52 PSI.

Now the question arises as to why the tyre pressure increased so drastically. We used a thermometer to check the exterior tyre temperature. The temperature highlighted it at 92.5°C. Now all the pieces of the jigsaw was before us along with the complete picture.

Analysis: The heat produced as a result of the friction of the tyres with the road surface and the rubbing of the brake pads constantly, expanded the air inside the tyres to such an extent that the air pressure increased proportionately as a result. However our tyres, as an exception, contained air pressure in accordance with the international standards from the beginning. But for those tyres which had air pressure more (35-45 PSI) from the beginning itself or had cuts on the circumference, the probability of accident for such tyres increases exponentially.

Hence it is submitted: Before driving on the Taj Expressway, get the correct air pressure for your car tyres and enjoy the journey safely. It is also requested of the Expressway authorities to create an awareness on this topic for all drivers on this route so that it is not their last journey.

Credit: Translated from the originally article by Manoj Gupta in Hindi published in a social networking site.

[samarth.bhatia]

And no doubt pressure is the most important factor for not just this, but other concrete highways as well.
Was the speed rating of the tires on the X1 checked? That could also affect the heating, and hence increase in air pressure.

[sandeepmohan]

Originally Posted by SJD@NewDelhi

First, we checked the pressure of the tyres and set it to 25 PSI. We maintained a speed of 150-180 kmph. On checking the tyre pressure before Agra, we were presented with startling results. The tyre pressure was 52 PSI.

A difference of 25 to 52 PSI is something you will feel quite easily.

At the speeds you were doing, I would have checked pressure after something like 25-50km, just to be safe and aware of what is happening.

You were doing really high speeds. I have seen a increase in the range of 2 psi on hot summer days, speeds in the vicinity of 80-120kmph.

Its also down to ambient temperature. It is quite possible that tire bursts are observed more in summers than winters.

I suggest a controlled environment if you want to do something like this.

[JayPrashanth]

Originally Posted by SJD@NewDelhi

An attempt at explaining the reason behind the Taj expressway accidents:


Credit: Translated from the originally article by Manoj Gupta in Hindi published in a social networking site.

More importantly, stay within the speed limit. It's there for a reason. That will solve a lot of issues and save a lot of lives.

PS: The Taj Expressway is a tyre eater.

Cheers,

Jay

[bravo6]

Originally Posted by SJD@NewDelhi

...the pressure of the tyres and set it to 25 PSI, in accordance with the international standards (cars in all developed countries maintain this pressure level diligently...

Lower pressure = greater sidewall flex = more heating of the tyre.

Also lower pressure is suitable for good (smooth) roads only. If the required pressure is not met, the impact of going over huge bumps/potholes (rarity in developed countries) will be transmitted to the alloy, which may break.

The pressure difference is quite high. Did you use the same guage both times?

On a related note, if it is raining heavily out, I don't bother to check the tyre pressure. Less pressure on wet roads gives more traction.

[Altocumulus]

Another option is using nitrogen gas, when travelling on highways. Its available in most cities now. The gas doesn't expand with heat and helps to keep the tires cool as well.

[wantarangerover]

I think the OP has inadvertently found out the reason for the accidents - high speeds way above legal limits on tyres rated for much lesser speed.

The heat - air expands - tyre bursts part is pretty obvious I suppose. I don't know why you need any analysis to find that out.

[rajivr1612]

Correct me if I am wrong.
I believe that under inflated trye will cause more flex in the side walls. This flexing over a period of time may cause crack on the side walls eventually leading to a tyre burst. The flex will be minimal on a slightly overinflated tyre. Also speeds should be maintained as per the speed rating of the tyre.

[singhsid]

Originally Posted by SJD@NewDelhi

Hence it is submitted: Before driving on the Taj Expressway, get the correct air pressure for your car tyres and enjoy the journey safely. It is also requested of the Expressway authorities to create an awareness on this topic for all drivers on this route so that it is not their last journey.

Wait - isn't it more logical to just stick to the speed limit rather than advising low/high tire pressure??

The authorities have already done the heavy lifting by finding out a speed that offers a nice margin of error so I don't see why they should suggest a solution that does not address the problem at all - why violate the legal speed limit willingly for no reason?

[rajeev k]

What is the speed rating of the tyres on the BMW X1 test car, the make of the tyres and what is the car manufacturer suggested air pressure?
Ut would be interesting to analyse the rate of temperature rise on tyres inflated to 30 PSI.

[SJD@NewDelhi]

Originally Posted by samarth.bhatia

The speeds mentioned are way above legal Limits.
I suggest you edit out that part.

Facts are fact! What is the point of test results if you furnish edited testing conditions? Also, it was important to test at above discussed speed as most of the cars (and esp. the high end ones) drive at same or more speed in the same expressway. Sam, tell me honestly, haven't you ever driven at that speed or nearer to that speed even once in that expressway?

Originally Posted by sandeepmohan

I suggest a controlled environment if you want to do something like this.

Thanks for the feedback. But if you glance at the credits, you'll notice that I haven't conducted neither participated in the test. I am sharing for the sake of awareness.

Originally Posted by JayPrashanth

More importantly, stay within the speed limit. It's there for a reason. That will solve a lot of issues and save a lot of lives.

It was a test, which wasn't conducted by me. But thanks, shall convey the same to the appropriate parties.

[samarth.bhatia]

Originally Posted by SJD@NewDelhi

Facts are fact! What is the point of test results if you furnish edited testing conditions? Also, it was important to test at above discussed speed as most of the cars (and esp. the high end ones) drive at same or more speed in the same expressway. Sam, tell me honestly, haven't you ever driven at that speed in that expressway?

Sjd Sir, I have no pleasure in staying that I have. But that was not at speeds mentioned.
Also, conducting such a test without appropriate permissions is not the best idea - for every road users safety, including the tester.

That said, would really like to get more details if they're available.

[ad3952n]

Originally Posted by SJD@NewDelhi

We got the BMW X1 SUV from one of our team-members for the test. Next, we left for the Taj expressay from Noida. We maintained high speeds.

Suraj, as a responsible person and driver high speed driving is outrageous. None of us shall ever advocate maintaining such high speeds in order to experiment or arrive at any type of conclusion. I am sure you must be knowing that Taj Expressway has a defined speed limit of 100 kmph for cars and 60 kmph for heavy vehicles.

I highly recommend you to always keep the speed under control and also give you a friendly suggestion of not taking any car for granted. It's a machine at the end of the day and a slight human error can be far more dangerous.

Analysis: The heat produced as a result of the friction of the tyres with the road surface and the rubbing of the brake pads constantly, expanded the air inside the tyres to such an extent that the air pressure increased proportionately as a result.

Not trying to be a technical wizard, but instead of using normal air and increasing the tendency of Tyre bursts why can't we use Nitrogen air as an option since it keeps the Tyre cool and even punctures also occur seldom.

But for those tyres which had air pressure more (35-45 PSI) from the beginning itself or had cuts on the circumference, the probability of accident for such tyres increases exponentially.

No doubt, To curb this thing I guess creating awareness is the right way. However, now many people do understand that increasing the air pressure beyond a certain level does impact the overall ride quality of the vehicle.

Hence it is submitted: Before driving on the Taj Expressway, get the correct air pressure for your car tyres and enjoy the journey safely.

Your submission is partial as maintaining a responsible and safe driving pattern is equally important on Taj Expressway or even at any other road for that matter along with air pressure.

Lastly, Correct me if I am wrong, BMW does not come with spare wheel and in the event of a flat Tyre it can still travel up to certain distance at some 50 kmph. You should have taken a less-advanced car which could have given you much better results about your experiment.

Thanks.

[Turbanator]

First, we checked the pressure of the tyres and set it to 25 PSI, in accordance with the international standards (cars in all developed countries maintain this pressure level diligently while most of the people in our country are either not aware of this or maintain pressure level as high as 35-45 PSI in order to get higher fuel economy).

I seriously doubt this information , am yet to see these kind of low pressures in any of Cars that I own in India ( including CBU ) as well overseas .

have a look at BMW X1 pressures from a UK site

http://www.puretyre.co.uk/bmw-tyre-pressures/

On checking the tyre pressure before Agra, we were presented with startling results. The tyre pressure was 52 PSI.

Again this looks doubtful , from 30 or so to 52 - irrespective of increase in temperature in running conditions

Credit: Translated from the originally article by Manoj Gupta in Hindi published in a social networking site.

if you have merely translated this from some Hindi newspaper or similar - definitely far from facts .

[SS-Traveller]

Originally Posted by SJD@NewDelhi

The question arose in my mind as to why such incidents are happening so frequently...

How interesting. Did the researcher perform crash investigations in each case and determine whether the tyre bursts happened *before* or *as a result of* the crash?

Saying...

The cause behind majority of the accidents were the same - tyres getting punctured while on high speed...

is rather presumptuous in the absence of evidence in support.

We got the BMW X1 SUV from one of our team-members for the test. Please keep in mind, the original focus would be on the tyres.

And how many BMW X1s have crashed on the expressway for the researcher to choose this particular car? He should have taken the commonest car to have crashed - which can well be revealed by trawling the data on all crashes on this road.

First, we checked the pressure of the tyres and set it to 25 PSI, in accordance with the international standards (cars in all developed countries maintain this pressure level diligently while most of the people in our country are either not aware of this or maintain pressure level as high as 35-45 PSI in order to get higher fuel economy).

Does BMW India recommend 25 psi for the tyres they install in India? Data frm which developed countries is being used here?

We maintained high speeds. After driving the car in this manner for about 2 hours...tyre pressure was 52 PSI.
We used a thermometer to check the exterior tyre temperature. The temperature highlighted it at 92.5°C. Now all the pieces of the jigsaw was before us along with the complete picture.

What temperatures do F1 car tyres run at?

However our tyres, as an exception, contained air pressure in accordance with the international standards from the beginning. But for those tyres which had air pressure more (35-45 PSI) from the beginning itself or had cuts on the circumference, the probability of accident for such tyres increases exponentially.

Does one infer that running lower pressures is safer? Those were presumably run-flat tyres, so the researcher could have started off by running them flat and expected them to fill up as they heated up!

It is also requested of the Expressway authorities to create an awareness on this topic for all drivers...

True - the expressway authorities should put up signs saying ***Dumb researchers not welcome on this expressway***.

Originally Posted by Altocumulus

Another option is using nitrogen gas, when travelling on highways. Its available in most cities now. The gas doesn't expand with heat and helps to keep the tires cool as well.

Wrong notion. Do some reading:
http://www.edmunds.com/car-care/shou...-nitrogen.html
http://www.arb.ca.gov/cc/tire-pressu...lipr051308.pdf