Measuring Winners and Losers from the New I-35w Mississippi River Bridge

Abstract

The opening of the replacement for the I-35W Mississippi River Bridge bridge on September 18th, 2008 provides a unique opportunity to evaluate the impacts generated by this additional link on network performance, and thus empirically test whether a Braess Paradox occurred. Using detailed GPS data to estimate travel times on links and for origin-destination pairs, this research finds that while on average travel time improved with the reopening of the bridge, the subsequent restoration of parts of the rest of the network to their pre-collapse configuration worsened travel times significantly on average. In all cases, the distribution of winners and losers indicates clear spatial patterns associated with these network changes. While no Braess paradox was found in this case, the research provides a method for measuring such phenomena.