Modeling and Optimization of Traffic Flow in Urban Areas - Czech ...

Chapter 1IntroductionThe urban traffic is significantly increasing in the large cities. Fig. 1.1 showsthe progress of registered vehicles in Prague during this decade [Prag 09]. Asthe number of vehicles in the street (given by the density ρ) is increasing, theaverage speed w is decreasing. Similar to computer networks, from a certainstate increasing density ρ decreases the traffic flow rate q, which correspondsto a throughput of vehicles through the city. The cut-off point is given by thetraffic stream model [Haef 98] describing relationships among these parameters.See Fig. 1.2, where the fundamental diagram (graphical representationof traffic stream model) of real data from the Prague street “Zborovská” isshown. Large number of vehicles and traffic flow decreasing to zero bringsnumber of vehicles10 x 105 9.598.587.576.562001 2002 2003 2004 2005 2006 2007 2008 2009 yearFig. 1.1: Number of registered vehicles in Prague (different methodology was usedin the years between 2004 and 2008)1