Information AboutTraffic Flow |
| CATEGORIES ABOUT TRAFFIC FLOW | |
| road transport | |
| mathematical physics | |
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The first attempts to give a mathematical theory of traffic flow dated back to the 1950s, but to this day we still do not have a satisfactory and general theory to be applied in real flow conditions. This is because traffic phenomena are complex and nonlinear, depending on the interactions of a large number of Vehicle s. Moreover, vehicles do not interact simply following the laws of mechanics, but also due to the reactions of human drivers. In particular, they show phenomena of Cluster Formation and forward and backward-propagating Shock Wave s of vehicle Density . Fluctuations in measured quantities (e.g. Mean Velocity of vehicles) are often huge, leading to a difficult understanding of experiments. Vehicular traffic flow analysis is made more complicated by the "sideways parabola" shape of the speed-flow curve. As the total number of vehicles operating on a roadway reaches the maximum ), at densities beyond a point known as the "optimum density" the traffic flow becomes unstable. At that point even a minor incident can lead to a breakdown in traffic flow, resulting in persistent Stop-and-go driving conditions. Estimates of jam density, the density associated with completely stopped traffic flow, are in the range of 185-250 vehicles per mile per lane, while optimum densities for Freeway s are typically 40-50 vehicles per mile per lane. Scientists approach the problem in mainly three ways, corresponding to the three main scales of observation in physics.
The engineering approach to analysis of highway traffic flow problems is primarily based on (TRB), which is part of the United States National Academy Of Sciences . SEE ALSO
EXTERNAL LINKS REFERENCES A survey about the state of art in traffic flow modelling:
A useful book from the physical point of view:
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