In summer 2013, the City of Edmonton closed the Stony Plain Road Bridge crossing over Groat Road for four months as part of its roadway rehabilitation program. In order to estimate traffic diversion and evaluate network traffic impact during the construction period, a dynamic traffic assignment (DTA) model was developed using INRO’s Dynameq platform. Unlike the standard practice where both the model calibration and validation utilize traffic data collected under a same traffic condition, this model adopted a unique approach with the pre-construction (bridge open) traffic data for model calibration and the during-construction (bridge closure) traffic data for model validation. The primary motivation behind this approach was to assess the forecasting credibility of DTA models in estimating traffic diversion due to roadway constructions in the City of Edmonton.
This paper presents the DTA model development and traffic impact evaluation process, which covers data collection and analysis, traffic demand adjustment, the challenges with the DTA model network preparation, as well as model calibration and validation using the traffic conditions observed before and during the Stony Plain Road Bridge closure. The findings and lessons learned from this study are expected to benefit practitioners in the application of a DTA model in evaluating traffic operational performance measures for future construction projects.
Currently, the City is conducting an accessibility study to analyze traffic impact during the construction of upcoming major developments and transportation infrastructure projects in Downtown Edmonton. Building on the constructive experience with the Stony Plain Road DTA model development, particularly from the model validation using a second data set, the City’s Transportation Department decided to further expand the current DTA model boundary for the Downtown Accessibility Study. The new model will be considered as a primary tool to assess the traffic impact in the downtown area during a multi-year construction period.