Geospatial

GIS Aids in Search for Lost Hiker

Man lost in California's rugged San Bernardino Mountains.

by / September 3, 2008 0

During a visit to his vacation home in Green Valley Lake, Calif., in the San Bernardino Mountains, retired educator Dean Christy decided to go for a hike in the crisp winter air. But soon after he ventured out into the rugged terrain, a storm moved into the area. On Jan. 4, 2008 at 4:15 p.m., the 62-year-old called 911 from his cell phone, reporting that he was disoriented due to limited visibility in dense fog.

Search and rescue (SAR) teams were hastily dispatched to look for the missing hiker. As the hours stretched into days with no success, the San Bernardino County Sheriff's Department's (SBSD) Mobile Mapping Unit joined the operation to produce a variety of maps to assist in the search. The Mobile Mapping Unit created the maps using GIS technology, which helped determine where to concentrate the search for Christy, pinpoint areas already covered by searchers and brief Christy's family about the search's progress. To try to narrow the search areas, GIS was also used to conduct a viewshed analysis of the zone where Christy likely used his cell phone.

"The benefit to having on-site mapping is that we can use downloaded data provided by searchers from the current day to prepare for the next operational period," said incident commander Cpl. Bryan Lane of the SBSD. "In the case of a search and rescue, we use the maps to analyze areas physically covered by personnel in the field and then direct resources into areas not searched yet."


Wretched Conditions
The first SAR team to reach Green Valley Lake to search for Christy was the Rim of the World Search and Rescue Team. They arrived at about 6:30 p.m. on Jan. 4, near the Green Valley Lake campground, located approximately one-eighth of a mile east of the Christy home. They were greeted by freezing rain and heavy winds gusting up to 90 mph. Confinement and attraction tactics were used throughout the night, including emergency vehicle lights, sirens and public-address systems.

During the initial call, Christy told the 911 dispatcher that he was dressed warmly and was prepared to stay outside by taking shelter under a rock outcropping located about 50 feet from where he was making the call. That was the last time anyone heard from him. (At about 10 a.m., Jan. 5, Christy attempted to make a cell call to access his voicemail. The call was not completed, and that was the last time Christy used his phone.)

At about 2 p.m. on Jan. 5, the rain turned into a blizzard that continued until early Jan. 7, dumping nearly 6 feet of snow in the primary search area. During the next eight days, SAR teams from all over Southern California and as far north as Lake Tahoe and the San Francisco Bay Area joined the search. Helicopters and snowcats brought searchers and their equipment into the field. When aviation assets weren't being used for shuttling searchers into the area, field observers would fly during the day when weather permitted, and at night the helicopters were equipped with forward-looking infrared sensors; the pilots wore night-vision goggles that can detect aboveground body heat.

The Incident Command System was used to manage this massive rescue operation; approximately 100 searchers were assigned each day.


Mobile Mapping Unit
When the search for Christy expanded to 30 square miles on Jan. 10, Lane decided to increase the on-site map production capability by bringing in the SBSD's Mobile Mapping Unit. This 40-foot custom motor home contains a generator, two networked GIS workstations, a color copy machine, remote satellite access to the Internet and a large-format Hewlett-Packard plotter for making 36-by-44-inch briefing maps. SBSD personnel staff the Mobile Mapping Unit, and the members include a situation unit leader, a GPS technical specialist and two public information officers. Two additional GIS technical 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.


Viewshed Analysis
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.


Body Found
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.

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.


Viewshed Analysis
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.


Body Found
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,

the microphone has a sunlight-readable display that shows the user's location and the location of and distance from all other team members on the same frequency. Another useful enhancement is the ability to send text messages over a radio frequency and read them from the microphone's display. From the incident command post or any command vehicle within radio range, search managers can keep track of all SAR personnel, aircraft, canine units, snowcats and other resources in real time just by looking at their laptop screen running RedZone software. This frees up the radio frequencies for essential transmissions and takes the guesswork out of trying to determine personnel location either day or night. In the very near future, search teams returning to the incident command post will see their track logs already displayed in the Mobile Mapping Unit, and maps of their search progress will be printed and waiting for their approval.

GIS is now widely recognized as an essential tool for making faster, safer and more informed decisions. This is particularly useful in SAR, where so much is at stake. One of the most important advantages of using GIS in SAR missions, and one that pleases the risk managers, is thorough documentation. These maps would make great exhibits during any litigation that may arise from a search.

There's no doubt that GIS has become an important tool for search managers," said John Amrhein, SBSD's Situation Unit leader. "GIS allows us to make better-informed decisions on where to concentrate searchers in the following operational periods. Being able to know exactly where a team has searched is invaluable, whereas in the past you would just have the teams' best guess as to what areas they had covered. I am also very excited about the possibilities of the new technology of live tracking search assets in the field, not only from a search management view, but also for searcher safety issues. Also, as in any operation, documentation is important, and GIS provides this very nicely."

 

For more information about the San Bernardino County Sheriff's Department Mobile Mapping Unit, GIS for Search and Rescue training course, and real-time GIS rescue applications, contact John Amrhein, Tom Patterson or Clark Woodward.

 

Tom Patterson Contributing Writer
Tom Patterson is an ESRI Wildland Fire Specialist