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

Chapter 5Traffic Flow OptimizationThis chapter proposes consecutive steps to find the optimal offset and thesplit of the light controlled intersections in the urban traffic region. Theoptimization takes into account the street length, number of lanes and maximalallowed vehicle speed in consideration to respect the green wave strategycontrol and constant intersection cycle time. The solution of this problem isshown on the urban traffic region in Prague. The problem is formalized andsolved by the TORSCHE.5.1 IntroductionThe light controlled intersections are characterized by several parameters:the number of light phases, phase split, offset time and a list of streets fromwhich the vehicles flow [Gube 08]. The term phase means state of trafficlights on the intersection. The number of phases and the list of streets arepartially given by the urban architecture of the intersection and partiallyby the intersection control strategy (i.e. one-way street, directional roadwaymarking). Both of these parameters are constant. On the other hand, thesplit and offset can be changed dynamically during a day. The split τ vjdefines the time interval of phase j for which the vehicle flow can go throughthe intersection v from one or more streets [Papa 03]. The offset ϕ uv is acertain time delay between phases of two successive intersections u and v.When the offset is zero, all lights in the region turn on and off at the sametime. It is called the synchronized strategy. In the green wave strategy, the53