Browsing by Subject "Collapse"
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Item Development of the Next Generation Metro-Wide Simulation Models for the Twin Cities' Metropolitan Area: Mesoscopic Modeling(2011-01) Liu, Henry X.; Danczyk, Adam; He, XiaozhengThe collapse of the Interstate 35W Bridge over the Mississippi River in Minneapolis resulted in unexpected loss of life and had serious consequences on mobility and accessibility in the Twin Cities metropolitan area. In response to the network disruption caused by the bridge collapse, a number of traffic restoration projects were proposed and rapidly implemented by MnDOT. Selection and prioritization of these projects, however, was based mainly on engineering judgment and experience. The only decision-support tool available to traffic engineers was the regional transportation planning model, which is static in nature and decennial. In this work, the Twin Cities metropolitan area is simulated using a mesoscopic traffic simulator in the AIMSUN software. After establishing the mesoscopic simulation model, we attempt to utilize the calibrated mesoscopic simulation model to evaluate drivers’ perceived cost evolution to explain the traffic dynamics on the Twin Cities road network after the unexpected collapse of the I-35W Bridge over the Mississippi River. Given the observation of largely underutilized sections of network, it is proposed that the tragedy generated a perceived travel cost to discourage commuters from using these sections. Applying a mesoscopic simulation model provided by AIMSUN, the perceived costs on cordon lines after the I-35W Bridge collapse were suggested to be best described as an exponential decay cost curve. The proposed model is applicable to both practitioners and researchers in traffic-related fields by providing an understanding of how traffic dynamics will evolve after a long-term, unexpected network disruption.Item Traffic Flow and Road User Impacts of the Collapse of the I- 35W Bridge over the Mississippi River(Minnesota Department of Transportation, Research Services Section, 2010-07) Zhu, Shanjiang; Levinson, David; Liu, Henry; Harder, Kathleen; Dancyzk, AdamMajor network disruptions have significant impacts on local travelers. A good understanding of behavioral reactions to such incidents is crucial for traffic mitigation, management, and planning. Existing research on such topics is limited. The collapse of the I-35W Mississippi River Bridge (August 1, 2007) abruptly disrupted habitual routes of about 14,000 daily trips and forced even more travelers to adapt their travel pattern to evolving network conditions. The opening of the replacement bridge on November 18, 2008 generated another disturbance (this time predictable) on the network. Such “natural” experiments provide unique opportunities for behavioral studies. This study focuses on the traffic and behavioral reactions to both bridge collapse and bridge reopening and contributes to general knowledge by identifying unique patterns following different events. Three types of data collection efforts have been conducted during the appropriate frame of reference (i.e. before vs. after bridge reconstruction): 1) GPS tracking data and associated user surveys, 2) paper and internet-based survey data gauging travel behavior in the post-bridge reconstruction phase, and 3) aggregate data relating to freeway and arterial traffic flows, traffic control, and transit ridership. Differences in reactions to planned versus unplanned events were revealed. Changes in travel cost were evaluated and their temporal and spatial patterns were analyzed. This report concludes with thorough discussions of findings from this study and policy implications.