Modeling and Distribution of Link Travel Times: An Analysis on Istanbul Freeways

Travel times can be directly estimated by measurements including probe vehicles, Bluetooth detectors, and etc. Route and network wide travel times can be alternatively specified employing indirect estimation methods. These methods can be classified into two those are trajectory based and traffic flow model based. Considering the latter class, an approach to reconstruct travel times is to employ models commonly used in dynamic traffic assignment, where the travel time on a link is a treated as a function of the number of vehicles on the link. In the presented research, we concentrate on the reconstruction performance of two traffic flow models on freeway link/path travel times. A link performance function based macroscopic traffic flow model is employed and compared with a microscopic traffic flow model. Performances of selected methods are evaluated with the actual measurements on travel time. Actual travel times have been collected on weekdays by using a global positioning system (GPS) module equipped probe vehicle. Following reconstruction of link/path travel times employing macroscopic and microscopic models, an evaluation on the distribution of model calculations with the corresponding to GPS measurements presented.