Traffic Jam

Author Topic: Traffic Jam  (Read 655 times)

Offline bcdas

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Traffic Jam
« on: December 12, 2011, 11:24:00 AM »
Traffic Jam is a condition on road networks that occurs as use increases, and is characterized by slower speeds, longer trip times, and increased vehicular queueing. The most common example is the physical use of roads by vehicles. When traffic demand is great enough that the interaction between vehicles slows the speed of the traffic stream, this results in some congestion. As demand approaches the capacity of a road (or of the intersections along the road), extreme traffic congestion sets in. When vehicles are fully stopped for periods of time, this is colloquially known as a traffic jam or traffic snarl-up.


Traffic congestion occurs when a volume of traffic or modal split generates demand for space greater than the available road capacity; this point is commonly termed saturation. There are a number of specific circumstances which cause or aggravate congestion; most of them reduce the capacity of a road at a given point or over a certain length, or increase the number of vehicles required for a given volume of people or goods. About half of U.S. traffic congestion is recurring, and is attributed to sheer weight of traffic; most of the rest is attributed to traffic incidents, road work and weather events.[2]

Causes of Traffic Jam:

Traffic research still cannot fully predict under which conditions a "traffic jam" (as opposed to heavy, but smoothly flowing traffic) may suddenly occur. It has been found that individual incidents (such as accidents or even a single car braking heavily in a previously smooth flow) may cause ripple effects (a cascading failure) which then spread out and create a sustained traffic jam when, otherwise, normal flow might have continued for some time longer.[3]



Mathematical theories:
Some traffic engineers have attempted to apply the rules of fluid dynamics to traffic flow, likening it to the flow of a fluid in a pipe. Congestion simulations and real-time observations have shown that in heavy but free flowing traffic, jams can arise spontaneously, triggered by minor events ("butterfly effects"), such as an abrupt steering maneuver by a single motorist. Traffic scientists liken such a situation to the sudden freezing of supercooled fluid.[4] However, unlike a fluid, traffic flow is often affected by signals or other events at junctions that periodically affect the smooth flow of traffic. Alternative mathematical theories exist, such as Boris Kerner's three-phase traffic theory (see also spatiotemporal reconstruction of traffic congestion).

Because of the poor correlation of theoretical models to actual observed traffic flows, transportation planners and highway engineers attempt to forecast traffic flow using empirical models. Their working traffic models typically use a combination of macro-, micro- and mesoscopic features, and may add matrix entropy effects, by "platooning" groups of vehicles and by randomising the flow patterns within individual segments of the network. These models are then typically calibrated by measuring actual traffic flows on the links in the network, and the baseline flows are adjusted accordingly.

It is now claimed that equations can predict these in detail:

    Phantom jams can form when there is a heavy volume of cars on the road. In that high density of traffic, small disturbances (a driver hitting the brake too hard, or getting too close to another car) can quickly become amplified into a full-blown, self-sustaining traffic jam...

    A team of MIT mathematicians has developed a model that describes how and under what conditions such jams form, which could help road designers minimize the odds of their formation. The researchers reported their findings May 26 in the online edition of Physical Review E.

    Key to the new study is the realization that the mathematics of such jams, which the researchers call 'jamitons,' are strikingly similar to the equations that describe detonation waves produced by explosions, says Aslan Kasimov, lecturer in MIT's Department of Mathematics. That discovery enabled the team to solve traffic jam equations that were first theorized in the 1950s.[5]

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« Last Edit: December 12, 2011, 11:36:03 AM by bcdas »
Dr. Bimal Chandra Das
Associate Professor
Dept. of GED, DIU

Offline akabir

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Re: Traffic Jam
« Reply #1 on: January 29, 2012, 11:15:33 AM »
Thank you sir.

Offline sethy

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Re: Traffic Jam
« Reply #2 on: February 05, 2012, 11:47:13 AM »
Bangladesh is a poor country. But when I get out from home I think it is a wrong statement. Because there are a lot of privet car. A privet car carry one or two passenger. If we noticed that we can see the main reason of traffic jam is those privet car. So i think Government should take proper step against it. Govt. should take decisions either to build more road, flyover or to make limitation to buy more car.
Sazia Afrin Sethy
ID:101-11-1366
BBA Department,
Batch: 25th,
Sec: B.

Offline arefin

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Re: Traffic Jam
« Reply #3 on: February 08, 2012, 09:49:05 AM »
Buying car limitation will not work, As a citizen of a democratic nation anyone has the right to buy a car. Govt. has implemented this theory for last 3 years by increasing the price almost 350%. Still it did not solve anything. In my opinion govt. should take a very strict decision that all private vehicle will be run by Gasoline (like petrol, diesel etc), not CNG. In the meanwhile public transportation should be upgraded in a good standard and quality. Another thing, during the peak hour all private vehicle has to pay tax for the parking. these things are already implemented by many Asian and European nations. so we can take their plan and directly can implement it. Increasing the price of Car, CNG, Gasoline is not a solution. We have to be proactive rather than reactive.
“Allahumma inni as'aluka 'Ilman naafi'an, wa rizqan tayyiban, wa 'amalan mutaqabbalan”

O Allah! I ask You for knowledge that is of benefit, a good provision and deeds that will be accepted. [Ibne Majah & Others]
.............................
Taslim Arefin
Assistant Professor
Dept. of ETE, FE
DIU

Offline arefin

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Re: Traffic Jam
« Reply #4 on: February 08, 2012, 09:49:53 AM »
Anyway, thanks goes to BCD sir for raising this problem into forum.
“Allahumma inni as'aluka 'Ilman naafi'an, wa rizqan tayyiban, wa 'amalan mutaqabbalan”

O Allah! I ask You for knowledge that is of benefit, a good provision and deeds that will be accepted. [Ibne Majah & Others]
.............................
Taslim Arefin
Assistant Professor
Dept. of ETE, FE
DIU