ArcNews Online

Summer 2009

E-mail to a Friend
City of Fenton, Michigan, Uses GIS for Situational Awareness

Assessing Tornado Damage


  • All data was maintained within Esri personal geodatabases.
  • ArcView was used for tracking structure damage and monitoring the extent of power outages.
  • With ArcView and ArcEditor, the city and Red Cross met the emergency funding deadline.

The City of Fenton is a relatively small Midwest community located in the northwest corner of southeast Michigan. The city got its name in 1837, as the story goes, from the winner of a card game between William Fenton and Robert Leroy. The city was named after Fenton, and the main thoroughfare was named after Leroy. One hundred and seventy years later, on August 25, 2007, the City of Fenton experienced its largest emergency response situation in its recorded history. On that day, the region experienced severe weather that produced strong winds and several tornados. An EF2 tornado, with wind speeds of more than 100 miles per hour, touched down in the city. In a matter of minutes, more than 200 properties were damaged, including hundreds of trees that were uprooted or splintered, and a population of more than 12,000 was largely without power.

  click to enlarge
Maps were produced using GIS to show the tornado's path of most significant destruction. Parcel-based damage assessments were generalized into a damage path map for the local media and general public.

At the time of the emergency, the City of Fenton had been using GIS software since 2003. In addition, the idea of using GIS for damage assessment was not new to the city, as staff members had previously participated in damage assessment training and had an emergency response plan in place. With the help of its GIS consultant, the city had been exploring hypothetical tornado-path scenarios for developing first-response methodologies that would allow identification of residents that would need immediate response in case of an emergency. When just such an emergency became reality, GIS became the central feature used in coordination, management, mapping, and final damage assessment reporting.

Damage assessment was fully under way the day following the tornado. The objectives were, first, to ensure the safety of the residents and, second, meet the state-mandated deadline for submitting reports to receive emergency management funding (48 hours after the event). While damage assessment was spearheaded by the city, the American Red Cross provided a significant supporting role. Also, as a member of the emergency response team, the city's longtime GIS consultant, North Arrow Technologies, Inc. (a local Esri Business Partner), was tasked with assisting the Assessing Department with a GIS-based damage assessment.

The GIS team first used ArcView to produce maps for general orientation, allowing city and Red Cross officials to manage staff and volunteers for inspection of the city, block by block. In the field, inspection crews assessed the structural damage for each house on each tax parcel by assigning it into one of five classes ranging from 1 (unaffected) to 5 (destroyed). As inspection crews returned to the emergency operations center with damage information, the GIS team used ArcEditor to enter the damage assessment codes into the tax parcel layer. Having a central repository of this information in the GIS allowed not only near real-time updating of the neighborhoods that had been surveyed but also an immediate understanding of where the most severe damage had occurred. For media coverage, a map was produced showing the path of most significant destruction, which later proved to very closely match the National Oceanic and Atmospheric Administration's (NOAA) officially designated tornado path. In addition to tracking structural damage, ArcView was used in a similar fashion to monitor the extent of power outages. As reports of new outages or power reestablishment were coming in, maps were continually updated.

Primary data sources used in the damage assessment included the tax parcel layer, building footprints, and high-resolution aerial photography, as well as other common basemap features (e.g., street centerlines, hydrological elements). All data was updated or developed by North Arrow Technologies over the five years prior to the tornado's arrival. At the time, all data was maintained within Esri personal geodatabases.

  photo of uprooted tree
Wind speeds over 100 mph caused significant damage to commercial and residential structures in the City of Fenton. More than 200 properties were damaged including hundreds of trees that were uprooted.

In retrospect, several key issues were revealed that are being addressed by the city to further improve emergency preparedness for the future, especially related to GIS support. First, a formal emergency response GIS team should be established and included as part of the first-response team. Second, the emergency management headquarters should be outfitted with proper GIS facilities and access to enterprise data. Previously, the city's GIS software and data were housed in city hall but the emergency response headquarters were located in the fire hall. Fortunately, in this case, city hall was only several blocks away so members of the GIS team were able to move back and forth between the GIS facilities and the emergency crews. Finally, ensure that network facilities have mission-critical redundancies allowing for GIS operations in severe weather and limited power conditions. During the response, the GIS team learned that the storm (most likely the lightning) had damaged one of the network routers that linked the GIS workstations with the plotter. The network administrators quickly resolved the problem, but it did serve to hinder the ability to print maps for a short period of time.

In the end, with ArcView and ArcEditor leading the way, the city and Red Cross successfully assigned their response teams to the most critical areas and documented, mapped, and reported all 235 damaged properties prior to the emergency management funding deadline. This emergency management application of GIS was noted by many as very successful since situational awareness, volunteer management, and reporting were all handled in an organized manner and in a very short time. While the situation led to several lessons learned, the City of Fenton's investment in GIS proved invaluable during this historic event.

More Information

For more information, contact Tonya Molloseau, assessor, City of Fenton (e-mail:; Dick Beauchamp, damage assessment officer, Genesee-Lapeer Chapter, American Red Cross (e-mail:; or Dr. Jason J. Taylor, founder and partner, North Arrow Technologies, Inc. (e-mail:, or visit

Contact Us | Privacy | Legal | Site Map