Evaluating the Effects of I-35W Bridge Collapse on Road-Users in the Twin Cities Metropolitan Region

This study evaluates the e?ects of I-35W bridge collapse on road-users in the Twin- Cities metropolitan area. We adopted the Twin-Cities (Metropolitan Minneapolis and St. Paul) Seven-County travel demand model developed in previous research, re-calibrated it against July 2007 loop detector tra?c data, and used this model to carry out an evaluation of economic loss incurred by increased travel delay in alter- native scenarios before and after the bridge collapse. We concluded that the failure of the I-35W bridge resulted in an economic loss of $71,000 to $220,000 a day, de- pending on how ßexible road-users in the system can adjust their trip destinations in response to the bridge closing. We also estimated that the major tra?c restoration pro jects Mn/DOT has implemented in quick response to the bridge collapse can save road-users $9,500 to $17,500 a day. This translates into a beneÞt-cost ratio of 2.0-9.0, suggesting these pro jects are highly beneÞciary in an economic sense. In this analysis, the use of a simpliÞed, scaled-down travel demand model enabled us to carry out the analysis quickly and accurately, showing its contributions in transportation planning under situations such as emergency relief and comprehensive design.