September 3, 2008 By Tom Patterson
nical specialists from ESRI joined the team. They all worked comfortably within the confines of the heated vehicle during the 12- to 16-hour shifts. This arrangement made for a smooth workflow in which SAR teams would bring their GPS receivers, used to document their area searched, to the Mobile Mapping Unit at the end of the shift.
While the teams searched their assigned areas, their progress was recorded on handheld GPS receivers. Waypoints depicting the coordinates of any clues found, such as tracks, discarded food wrappers or items of clothing, were also recorded into the devices. At the end of the shift, these track logs were downloaded and converted into shapefile format by the GPS technical specialist using Maptech's Terrain Navigator Pro software.
Maptech is an ESRI business partner, and its mapping program is popular with many SAR teams and fire departments. It easily displayed and exported GPS track logs collected by the teams and converted them into a single shapefile. With ESRI's ArcInfo software, staff could then use the single shapefile to create a comprehensive search history and incident action plan maps. As the last team went through the debriefing process, it took little time to display an overall picture of the entire day's activities, which were also overlaid with previous operational periods. Search managers could tell at a glance where to deploy resources for the next day. GPS data was also downloaded from the AeroComputers Tactical Mapping System from each of the helicopters and displayed in ArcGIS. These aerial layers could be easily combined with the ground team's data to enhance the decisions being made for the next operational period. For example, the information helped determine which areas were adequately searched and which ones needed to be revisited.
"Additionally having a full map set with GPS track logs to put into the case file helps us direct future operations in the area and to document a higher standard of care," Lane said.
GIS was also used to attempt to pinpoint potential areas where Christy might have made his last 911 call. The California Highway Patrol's 911-dispatch center provided the coordinates of that location. The accuracy of that point was plus or minus 550 meters, and officials were convinced that it went through the Strawberry Peak cell site, 10.8 air miles away to the east in Rim Forest.
ESRI's ArcGIS Spatial Analyst extension was used to perform a viewshed analysis of all the areas within a 1,000-meter circumference surrounding the location where Christy placed the call that had a line of sight to the Strawberry Peak cell tower. Searchers made cellular phone calls from random locations in the zone identified as the one from which Christy called for help. The calls made within the shaded areas were able to connect with the 911 dispatcher through Strawberry Peak; those outside the orange polygons on the map either couldn't connect or else connected through cell towers on the Victorville side of the mountain. This map, along with the search history maps, was used to brief Christy's family and help incident commanders make an informed decision to scale back the operation on the afternoon of Jan. 13.
However, the search remained active. On April 4 - three months to the day since he went missing - the Rim of the World Search and Rescue Team found Christy's body northeast of Green Valley Lake, less than 1.5 miles from his home.
"On trails he had traveled approximately 3.5 miles," said the SBSD's Lane. "He sheltered between a rock and a large tree. It appears there may have been some branches on the rocks above him that he may have used to protect himself."
Christy was located in a rock outcropping in an area identified in the viewshed analysis as having line of sight to the Strawberry Peak cell tower.
"It was in an area that had been searched more than once, but he was probably covered with snow when searchers were there before," said Donna Newlin, commander of the Rim of the World Search and Rescue Team.
The team continued to conduct regular searches for Christy after the major operation had been scaled back. "We did something called a Mattson Consensus," Newlin said. "We gather all the available information and clues and ask as many experienced searchers as possible to circle areas on the map that they think he would be in. Based on the cell phone 'hit,' the clues he left verbally on the 911 tapes and the terrain, we had consensus - the group's combined gut feeling. The team had been slowly and methodically clearing snow-free areas and mapping our progress. We filled in places on the map where we could now say, with a higher degree of confidence, where he was not. The team finally got into the right area, and instead of knowing where he was not, we finally knew where he was. The GIS analysis of the cell phone hits definitely impacted our decision on which areas to focus."
Embracing Newer Technology
The use of geospatial technologies has gained wider acceptance by the SAR community in the last five years.
Today's search and rescue teams are more aware of the capabilities GIS can provide in the saving and safeguarding of human life. Only half the teams were equipped with GPS receivers during the search for Marvin Matsumoto in April 2003. Matsumoto - a 60-year-old hiker - got lost in Joshua Tree National Park. He was found alive after a five-day search, despite the fact that rescuers had been searching an area they hadn't intended to due to incorrectly entered GPS coordinates.
Every SAR team member now carries a GPS device that can be purchased for as little as $99. Working from the front seat of a patrol car with a vehicle-mounted laptop during the five-day search for Matsumoto was far more arduous than working inside SBSD's Mobile Mapping Unit during the search for Christy. Internet connectivity from remote areas was either nonexistent or extremely slow in 2003.
The 2008 search used a server that accessed a satellite broadband connection to retrieve ArcGIS Explorer 3D visualization enhancements. It was easy to overlay the polyline shapefiles created from the GPS track logs and display them in ArcGIS Explorer to create a three-dimensional map. Aerial imagery or topographic map data was displayed as a background and draped over digital elevation models. Roads and administrative boundaries could be added for reference. This gave a true representation of the terrain difficulty, which was much easier for field teams to understand than a two-dimensional topographic map with contour lines. SBSD personnel were especially impressed that all this information is available for the entire country and can be accessed through the freely downloadable ArcGIS Explorer application.
Today companies produce easy-to-learn GIS software programs designed specifically for search and rescue applications. One of the more intuitive applications, RZ3, is made by RedZone Software, is built on ESRI technology and has full-editing capabilities. The total time needed to learn this skill is less than four hours including field exercises.
During the search for Christy, a rugged, external GPS-enabled radio speaker/microphone was tested. It's an effective tool to enhance situational awareness and increase field personnel safety. Every time a SAR team member keys the radio to send a message, data consisting of coordinates, speed, heading, altitude and personal identity is transmitted. The device can also be programmed to automatically transmit at a specified time interval (i.e., every two minutes for ground teams and every 10 seconds for flight following of helicopters). In addition,
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