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On Thu, 21 Jun 2001, Paul Rosen wrote: > > In addition i also wondered if any members of the list had come across any > > literature concerning the application of chaos theory to traffic flows and > > traffic congestion > > I haven't, but I'd be very interesting to see any replies sent to the > list rather than privately - would a chaos theory analysis challenge or > reinforce conventional traffic modelling/planning wisdom? Dear Paul/ Friends, Last year, during my research at University of Newcastle we tried simulating heterogeneous and untidy traffic. To me the traffic in heterogeneous and untidy conditions is more chaotic than any other driving condition. We investigated the driver behaviour in a mixed traffic flow environment and concentrated on simulating traffic in Delhi, Dhaka and Bangkok. It looked into the relationship of varying driver topologies, based on age, sex, trip time and purpose and relative aggressive levels associated with trips in the three case locations based on their vehicle topologies. One of the finding of the study was that while heterogeneous and mixed traffic increases vehicle delays, and stops at the signalised links, untidy, traffic reduces it. The combined effect of heterogeneity and untidiness cancel each other. This is a key result that portrays an example of undesirable or un-optimised system being forced to Harmony due to Chaos. The heterogeneity in traffic leads to "negative" system performance or the system functioning less than its efficiency. And Untidy traffic due to poor lane discipline seemed to benefit the system performance. In totality the traffic systems in all case study areas seemed to be running in a self derived equilibrium that was perhaps best suited for that environment. It was also found out that the level of driver aggression in an environment is a function of, level of level of heterogeneity. Another interesting finding was that as congestion level increases, untidiness in the traffic reduces, as the drivers are forced to move in an "orderly situation" (best described in the case study of Bangkok traffic"). All these findings could well consolidate the fact that even though chaotic systems might not be desirable, they can lead to equilibrium and system optimisation under the defined set of rules. Ahuja S. (2000), Simulation of Heterogeneous Untidy Traffic at Signalised Links in Developing countries, University of Newcastle upon Tyne, Newcastle. Bell M. G. H., Iida Y., (1997), Transport Network Analysis, Wiley, Sussex. Sonal Ahuja Sonal Ahuja Email: [log in to unmask] JDT Canterbury House, 85 Newhall Street, Birmingham B3 1LZ Tel +44(0)121 237 4002; Fax +44(0)121 237 4003 Mobile: +44(0)777 184 8557 __________________________________________________ Mott MacDonald Ltd Registered in England no. 1243967 Registered office St Anne House, 20-26 Wellesley Rd, Croydon, CR9 2UL