Transportation planners are increasingly looking for ways to incorporate Dynamic Traffic Assignment (DTA) into regional planning applications especially in congested networks where forecasted V/C ratios are well in excess of system capacity. This is because such over congested conditions give rise to peak spreading and departure time shifts which must be accounted for during the assignment as well. Since DTA includes a time component in addition to a space component, it is able to better represent such over congested conditions compared to a static assignment which involves only a space component. In general, access to data sources which support DTA is increasing, however those familiar with traffic micro-simulation appreciate the challenges associated with increased requirements for calibration, validation and deployment of these models, especially compared with static methods. However, there are DTA methods that work with less rigorous data requirements. This paper discuses one such algorithm, Dynamic User Equilibrium (DUE) which can be used for simultaneous departure time choice and macroscopic dynamic assignment. In addition to explaining the properties of the algorithm the paper will demonstrate applications for incorporating peak-spreading effects into the model, feedback mechanisms that allow results (i.e. impedance) to be directly incorporated into the travel demand model and how newer data sources like historical speed profiles can be methodically used in the calibration and validation process for large scale networks.
The methodology will be explained and discussed with the help of relevant real world implementation examples, including the data generated from around the City of Pasadena, California developed for the US DOT Real-Time Data Capture and Management Program. This demonstration project developed a data set that fused a combination of real, observed data and modeled, synthetic data. The intent of this dataset was to support a common infrastructure that could support real-time traffic modeling. However, at the heart of the effort it also illustrates how the gap between planning and operations is closing and the synergies between each supporting and benefiting the other. In fact, the City of Pasadena is using data source as part of their long-range plan update process.