2007 Traffic Flow Study on the Effects of the Interstate 35 Bridge Collapse in Minnesota

The 2007 collapse of the Mississippi River Bridge on Interstate 35 in Minnesota disrupted approximately 14,000 daily trips and forced travelers to adapt to evolving network conditions. The 2007 Traffic Flow Study focuses on the traffic and behavioral reactions to both the bridge collapse and its reopening and identifies unique traffic patterns following extreme events.

Data Collection Agency

The Minnesota Department of Transportation conducted the 2007 Traffic Flow Study in collaboration with the University of Minnesota. The Oregon Transportation Research and Education Consortium (OTREC) conducted an associated study, dubbed the OTREC Study.

Methodology

The tragic bridge collapse provided a rare opportunity to evaluate the effects of a prolonged, unexpected disruption to a major transportation network as well as a unique window into travelers’ behavioral responses and decision-making mechanisms.

Immediately after the bridge collapse, researchers distributed mail-in questionnaires to drivers and transit users near major parking garages in downtown Minneapolis and the University of Minnesota. Following the reopening of the bridge, researchers collected data on driver behavior using global positioning system (GPS) devices installed in commuters’ vehicles to track travel times, routes, and speeds for 13 weeks and distributed additional questionnaires.

Researchers also obtained Minnesota Department of Transportation loop-detector data pertaining to highway network traffic volumes and speeds before and after the bridge collapse. They combined, geocoded, and analyzed all the data to evaluate driver behavioral reactions to the bridge reopening, and to compare traffic dynamics and network performance before the bridge collapse, immediately after it, and following the bridge reopening.

To expand the number of probe vehicles on the network and comprehensively evaluate changes in vehicle travel times across the network—especially on arterial roads where data collection devices such as loop detectors were not widely available—a GPS-based study (funded in part by OTREC’s Value of Reliability Project) was conducted concurrently. Study vehicles were equipped with GPS loggers to monitor travel trajectories at a frequency of one point per 25 meters, with data collected for up to 13 weeks (3 weeks prior to the reopening of the bridge and 8–10 weeks thereafter).

More Information

For an overview of the study, refer to the Responding to the Unexpected: Traveler Behavior and Network Performance in the Wake of the I-35W Bridge Collapse technical summary.

For detailed information, refer to the Traffic Flow and Road User Impacts of the Collapse of the I-35W Bridge over the Mississippi River report.

Transportation Data

Cleansed data are not available for this study. To gain access to spatial data via the TSDC’s secure portal environment, please submit an application.

This data package contains in-vehicle GPS data from 43 Traffic Flow Study participants and 97 OTREC Study participants. Trajectories are stored as ESRI shapefiles (.shp).

How To Cite the Data

If you use TSDC data in a publication, please contact us and include a citation in your publication consistent with the following format:

"Transportation Secure Data Center." [(year)]. National Renewable Energy Laboratory. Accessed [date]: www.nrel.gov/tsdc.