[sandys]

hi guys,
SCIENCE HOBBYIST: Traffic Waves, physics for bored commuters

this is an interesting traffic experiment that I read about - conducted over many years by a guy just messing around. Since then, it has been researched axiomatically by a lot of people.

Personally I think, the strategy mentioned in the above experiment might prove to be a bit impracticaly considering Indian driving styles, but it is highly interesting.

regards
Sandeep

[Ravveendrra]

Hey great article and yes long distance truck drivers in India too follow it when traffic is moving and they are not trying to overtake themselves. However if traffic stops they will leave exactly the gap required for the cleaner to get between the vehicles and clean the windshield etc.

Cheers,

[splitsecond]

great article indeed,i will do that wave eating experiment next time

Thanks for sharing.

[gpa]

A good article and an interesting read. Surprising what the human mind can come up with when bored

[Rehaan]

Interesting theory / video.

Here are two similar threads on Team-BHP :
http://www.team-bhp.com/forum/street...e-traffic.html

http://www.team-bhp.com/forum/street...behaviour.html

cya
R

[predatorwheelz]

Interesting thread, though purely for academic interest. My 2 cents:

Indian traffic too follows the same pattern of a steady flow of water, which each individual vehicle acting as a water molecule. However, 3 reasons why the theory doesnt hold much "water" in Indian traffic conditions:

1. In India, the molecules travel in an erratic manner. Lane driving is a norm rather than exception in US, while in India it is the other way around.

2. The theory uses freeway traffic in a lot of places as base. If we consider an Indian freeway (say a highway, or even a byepass within the city), the flow is hindered by a lot of elements other than the water molecules.

3. All water molecules do not travel at the same speed, for unknown reasons.

Still not convinced? I'll illustrate with my own example.

My daily commute to office is 17 kms, consisting of 4 stages:

1. 5 kms within Salt Lake - Anyone who's been to Kolkata would agree that Salt Lake, being a planned township, is much better than the rest of the city in road layout and traffic flow. Does that allow faster traffic movement within the township? No.

Salt Lake is plagued by autorickshaws, cycle rickshaws and buses, even on the main arterial roads that take commuters out of it. On a daily commute, one would notice the auto or bus ahead of him inching out of lane every time theres a passenger in sight. Note I said "passenger" instead of "stop", for India is still to understand the Utpoian concept that passengers should be picked up only from designated stops. See a passenger, move out of lane to pick him up, and Bob's your uncle.

Unfortunately, what this means is that car traffic, the kind that is trying to maintain a steady speed, is hindered continuously by a vehicle cutting across lanes every 20 mtrs. Instead of panic braking every 2 mins, the car driver soon learns to slow down and drive at snails pace so that the swerving and shifting ahead of him doesnt strain his nerves. Result? roads that could accomodate 60kmph traffic see average speeds of not more than 10-15kmph. Proves my first point.

2. 6 kms of Byepass - The Eastern Metropolitan Byepass was designed 25 years ago to allow traffic from the eastern part of the city to merge seamlessly with the centre. Unfortunately, some short sighted politician allowed buses to ply on it 5 years ago. With buses came the concept of stops, and with stops came jaywalkers getting down at random points and sauntering across the road - completely oblivious to oncoming 80kmph traffic! Plus obviously the aforementioned problem of buses cutting across lanes etc. Result? Average speeds of 20kmph in a 80kmph zone.

3. 3 kms of AJC Bose Road Flyover - Ah, now a 3 km straight flyover with no buses allowed on it should be ultimate motoring bliss, isnit? Not so in practice. Just when one endures the above 2 stages and breathes a sigh of relief as he approaches the flyover, a new drama starts. The flyover is the ultimate show off stage for the government vehicles and the ubiquitious Kolkata amby taxi. Both of these specimens hog a lane and proudly cruise along at 40 kmph. No amount of honking/light blinking will move these behemoths out of their intended lane. And if by fate you encounter 2 of these moving on parallel lanes, your dreams of covering the flyover in a flash are history. What was supposed to be a 2 min "fly" turns into a 15 min "crawl", with you and your engine growling in impatience. Proves my 3rd point.

4. 3 kms of Red Road and Dalhousie traffic - Aha, now here comes the most interesting part. Ideally, this stretch should have been the most slow, as all 3 elements I mentioned earlier converge here. But thanks to government top babus all stationed at Dalhousie, a traffic cop is stationed every 50 mtrs to avoid traffic clogs and allow Babus to sail through. What happens? Suddenly all traffic becomes orderly and starts to move at an uniform pace, resulting in this 3 kms becoming the fastest part of the trip.

Now that I've bored you enough, here's my version of the theory (applicable to India)

Indian traffic is like a stream of water, where most vehicles are like water molecules. Unfortunately, some are also stones/twigs carried along by the stream. An active traffic policeman is like the filter that cuts out all impurities, and allows the stream to travel as fast as it should.

Nuff said. Comments/criticisms welcome.

[sandys]

@predatorwheelz - you are right that Indian traffic is too much Brownian in nature. However, I have been trying this for a while as an experiment. While the success rate is not as much as it might be on US roads (where people dont usually cut in), it does reduce your braking.

[Rehaan]

Came across this cool little video showing how traffic (shock) waves happen :

YouTube - Shockwave traffic jams recreated for first time

cya
R

[Slick!]

Nice one rehaan! When the speed up the video it almost looks as if a few of them crash!!

[hrn658276]

Here is an very interesting article about Traffic Jams. Definitely worth a read
http://www.smartmotorist.com/traffic...ffic-jams.html

[EagleEye]

That was a very interesting article. I'm going to try and implement the "large gaps" idea on my commute. The only problem I think of, however, is that the gaps are going to be closed very fast with cars jumping in from all sides.

[hellmet]

That was a nice read. I just realized I was doing this without my knowledge of the science behind it. Most people would just step on the accelerator upon seeing clear road even if they can see all the stuck traffic just half km ahead. I just drive slower than other traffic and continue moving when I reach the end of the jam as it starts moving. Saves me petrol, it's easy on my vehicle components, and keeps me saner.

Also, one other thing I follow on the road when in situations when you and another driver are unsure who proceeds first: I just let the other driver proceed. Stay safe.

[sukhoi30]

Nice article and the physics behind it does seem universal. I always try to slow down way before a jam appears and also at signals so that by the time I reach the signal, the lights turn green (hopefully). I am tempted to try the technique suggested in the article to leave a large gap when the lanes are merging ahead. Well, for one, driver behind (especially if it is a high seated vehicle) will honk continously. Going by Indian drivers, there is a full chance that you or your vehicle get assaulted by this behaviour :-). Secondly, we will have multiple vehicles merging into my lane causing the gap to disappear quickly.
It will be a good idea if the traffic constables can use their motocyles to enforce this technique effectively.

[KPS]

Very interesting article. If you have been on the highway in the developed world, you will understand this article better as you can visualize it. However in India, in the absence of lane discipline this strategy is doomed as the gaps will get filled by cars overtaking you from the left. Unless there is change in driving culture where each driver is to himself and wants to be reach his destination in the least possible time, we have no hope.

Cheers

KPS

[ghodlur]

The article made a nice reading. Thats it.

However hard we try, the strategy will not work in this subcontinent clearly for the lack of patience and attitude to follow the traffic rules religiously. Add to that lack of spaces too. For us the lanes are white markings on the road. Period. Try using the strategy mentioned in the article and the vehicle giving way for others would either be scared off with the continous honking or some influential goon who may bein line behind the vehicle would come and bash up the poor driver with good intentions.

Typical scenario where I can relate to is at the toll booths until the dividers start right before the booths. Till then its a free for all lanes. Even after being in lanes, there are some morons who keep their vehicles at such an angle so as to make use of any opportunity to jump to the fast moving lane.