Technical Response Efforts

Technical Response Efforts


The response to the 35W Bridge collapse involved emergency response efforts at every level, from the citizen on scene to the mobilization of federal investigative resources and U.S. Navy rescue personnel.  Also among these were highly technical and innovative responses including the acquisition and distribution of aerial imageryfor the site, the activation and enhancement of a high-speed wireless internet network, and the development of an online traffic and route management application.


Mn/DOT - Aerometric Photogrammetry Project


AeroMetric is a major private aerial photography and mapping firm that maintains strong partnerships with Mn/DOT and many other governments and agencies of all levels. By 7:30 p.m. on the night of the collapse, AeroMetric's Photo Unit had contacted Mn/DOT to offer all of its capabilities in generating new imagery for the emergency response and rebuilding efforts. Around the same time, Governor Tim Pawlenty had publicly stated that the bridge would be rebuilt as soon as possible, and Pete Jenkins of Mn/DOT had received authorization for all necessary action and expenditure to facilitate the rebuild effort. To that end, Mn/DOT and AeroMetric personnel met and established a contract by early on the morning of August 2, 2007.  [1]


One of the oblique aerial photos taken by the Aerometric helicopter crew on August 2nd. From Mn/DOT's bridge collapse website.

By approximately 2pm on August 2, 2007 operating for Mn/DOT, AeroMetric's helicopter was surveying the site carrying their most experienced photographer, who took in excess of 300 high-quality digital oblique aerial photographsfrom every accessible angle of the site. Incident Command - those who would eventually centralize security operations at the site including airspace authority - was not completely unified at that time, and upon landing, AeroMetric's photographer and pilot were briefly detained by State Patrol officers who had followed and landed behind them in another helicopter. The proper authority was established in a short time and the crew was released and delivered the digital photos, which were quickly put to use by responders at the on-site Command Post and the Emergency Operations Center (EOC) downtown. [1]


By August 3, 2007 the FBI, NTSB, and others were all on site in Minneapolis, placing additional demands on coordination and making physical and data security a factor for all responders. Print enlargements of the photos taken the previous day were made and distributed to these agencies and the other responders on the ground in the morning. A second mission by airplane took extremely high-resolution (3-inch pixels) photography and LiDAR scans that afternoon, and flew directly to a processing facility in Ohio to expedite completion. This photography and the LiDAR data enabled Mn/DOT and federal agencies to generate an incredibly high-accuracy three-dimensional model of the terrain. The photos and model became essential to the emergency workers, demolition crews, and rebuild teams alike. Subsequent flights required still more in-depth coordination, as the helicopter's communication systems interfered with those of the U.S. Navy rescue divers on site, but did continue over the following weeks to provide frequent updates on the rapidly changing ground conditions. [1]


Minneapolis Wifi


A USI Wireless access point in south Minneapolis. Photo by Flickr user pfhyper.

In September of 2006, the City of Minneapolis selected USI Wireless as their private sector partner to develop a subscriber-based citywide broadband wireless internet service. [2] One consideration in undertaking this relatively unproven type of public project was the potential improvement of emergency response in the event of a major disaster, with higher-speed capabilities dedicated for just such contingencies. Although construction on the network was only approximately twenty percent complete by August 1, 2007, that twenty percent included the entire downtown area and neighborhoods on both ends of the bridge. [3]


Within minutes of the bridge collapse, cellular phone networks became overloaded and were unable to connect calls. USI Wireless executives attempting to contact Minneapolis officials to offer support experienced this failure of service, and immediately opened the wi-fi network to unrestricted use. Although transmission equipment at the river itself was initially lacking, USIW teams completed installation of additional high-capacity equipment along the 10th Street bridgeand elsewhere around the collapse site by approximately 10 am on August 2, 2007. At the same time and through the next day, several high-resolution video cameras were installed at multiple locations to assist rescue, management, security, and the other efforts ongoing at the site. The high capacity of the system enabled real-time transmission of data from these cameras to users at the EOC in downtown Minneapolis and to Command Post crews on site, as well as large Geographic Information Systemsfiles and other data including the Mn/DOT-Aerometric imagery. [4]


The rapid activation and enhancement of the wi-fi network not only enabled computing applications to be implemented rapidly, but also helped alleviate the cellular network load, as wi-fi enabled phones could also work on USIW's service. [4]  Approximately 6,000 users were reported to have used the service over the first day, in comparison with a subscriber base at the time of 1,000. After about 24 hours, the network was again closed to the general public, and dedicated to the agencies involved with the response efforts, official city use, and the existing subscribers. [3]

Minneapolis Reroute Application


The City of Minneapolis quickly recognized the dramatic impact on commuting and business that would be caused by the absence of the 35W Bridge, and identified the need for an accurate, accessible means of providing up-to-date detour and road closing/opening information to citizens and workers in the city. Existing online applications such as Google Maps and MapQuest were inadequate, as they could not be updated moment to moment as conditions changed. A solution that would allow city personnel to update each road and crossing in the area at any time was needed. To accomplish this, they turned to commercial Geographic Information Systems (GIS) software leader ESRI.[5]


From the city's specifications and building on their existing web-based mapping tools, ESRI programmers were able to develop a simple street map application that would allow live, finely detailed adjustments by city staff and serve up graphical and textual route descriptions for commuters. The application was built, tested, and delivered by the evening of August 3, 2007 within approximately 48 hours of the collapse. Local ESRI staff worked with Minneapolis GIS staff to fine tune the tool as desired, and over the weekend the application was deployed for public use on the City of Minneapolis website.[5]


The application remains online and usable via the City's Detour Reroute Planner web page.




1. Jenkins, Pete, Miles Strain, and Dan Ross. “Interstate 35W Bridge Collapse Emergency Response Mapping.” ASPRS Western Great Lakes Region Annual Dinner Meeting and Reception. St. Paul, MN. Feb. 7, 2008.

2. Minneapolis Selects US Internet for Citywide Wireless. Press release. US Internet. Sept. 5, 2006.

3. Thibodeau, Patrick. New Wi-Fi network proves critical in Minneapolis bridge disaster. Computerworld. Aug. 3, 2007.

4. Farstad, James. Minneapolis Bridge Collapse Provides Early Test of Wi-Fi Network. The W2i Report: Weekly Newsletter. Aug. 6, 2007.

5. Shields, Barbara. Bridge Reroute Application Helps Minneapolis Cope with Disaster. Government Technology. Oct. 1, 2007.