On a frigid night in December 1999, two firefighters rushed into the burning Worcester Cold Storage Warehouse in Massachusetts, intent on saving the lives of the homeless people sheltered in the abandoned, dilapidated structure. In less than two hours, they, and the two rescue teams sent to find them, became lost inside what had become a six-story cauldron. All six men died in the blaze.
The firefighters’ two-way radios were of little use because, under the pitch-black conditions inside the inferno, they couldn’t tell fire commanders where they were. The responders’ personal alert systems were of no use either. The first two firefighters had activated their systems, which emit a piercing sound intended to guide rescuers to the location. But the warehouse’s nearly half-meter-thick walls, covered with a half-meter of insulation, made parts of the building nearly soundproof.
In the tragedy’s aftermath, researchers at Worcester Polytechnic Institute (WPI), including IEEE Senior Members and electrical engineering professors David Cyganski and R. James Duckworth, began devising systems for tracking first responders in buildings and monitoring their vital signs so that they can be pulled out when conditions turn deadly.
“We were convinced that engineers could do better than the state-of-the art for rescue teams in 1999 and even now, which includes having people rope themselves together to keep from losing each other,” Duckworth says. But they found tracking people inside a structure a tough challenge. GPS won’t work inside buildings, and there was no suitable tracking device.
HELP WANTED Cyganski and Duckworth opted not to go it alone. WPI began hosting an annual workshop called “Precision Indoor Personnel Location and Tracking for Emergency Responders,” where engineers discuss devices they have developed for emergencies. The most recent workshop, held at the school in August, attracted more than 120 representatives from industry, academia, first responder departments, and government agencies.
During the workshop, the Worcester Fire Department tested five designs—including ones commercially available—in a simulated emergency. Rescue teams wearing masks obscured to simulate blackout conditions were sent into a campus building to find a “lost” comrade. The idea was to zero in on the most promising units.
According to Duckworth, WPI’s Location and Physiological Status Monitoring system, which he and Cyganski have worked on for five years, seemed to do best. It can track all firefighters at an emergency site and record the paths they’ve taken. Receivers on emergency vehicles parked nearby work together to decipher the signals, sorting out hundreds of straight-line and reflected signals to pinpoint the location of each transmitter in three-dimensional space. A commander outside can see where each firefighter is (and exactly how he got there) and direct the rescuers. In the test, the lost firefighter was found in less than 20 minutes, versus more than 45 minutes for a room-to-room search, well beyond the capacity of a firefighter’s breathing apparatus.
Another system tested was the Mobile Response Command System, developed jointly by ENSCO Inc., of Falls Church, Va., and Rex Systems Inc., of Racine, Wisc. The system features a rugged inertial measurement unit that’s strapped to the heel of a firefighter’s boot. About the size of a bar of soap, the unit relies on a suite of accelerometers, gyroscopes, and an altimeter to sense motion, including direction, velocity, and acceleration. Signal-processing algorithms then do real-time geolocation; the firefighter’s position is continuously updated on a display at the command station.
Another test was of WPI’s Mantenna wand, a homing device invented by Cyganski that detects a signal from a tiny beacon worn by a firefighter. The handheld Mantenna relies on lights and sounds to tell a rescuer the direction of and distance to the distress signal.
Also reviewed was the FRT 1000 from Draeger Safety Inc., Pittsburgh, Pa., first developed for finding avalanche victims buried in snow. (FRT stands for firefighter rescue transceiver.) Mounted on a firefighter’s breathing apparatus, the unit automatically emits a 457-kilohertz signal when he or she stops moving for 60 seconds. Units worn by others on the scene pick up the signal; bright displays and audible signals on their units tell them how close they are to the distressed firefighter.
One problem with radio homing systems is that their signals penetrate walls but don’t tell the rescuer anything about the layout of the building. They could direct a rescuer blinded by smoke to within two feet of a responder who might turn out to be behind a wall in another room.
The Pathfinder indoor navigation system from Summit Safety Inc., Devens, Mass., addresses this problem by not using radio signals. The company describes its handheld device, which resembles a radar gun for clocking the speed of pitchers’ fastballs, as a "high-tech electronic rope that is able to determine the quickest path between you and the firefighter in trouble." The tracking device detects an ultrasonic homing signal emitted by a beacon. Ultrasound won’t penetrate walls so rescue teams know they’ve found a clear path to their fallen comrade when the device indicates the signal is getting stronger.
A FURTHER GRANT In October, the U.S. Department of Homeland Security awarded the WPI team US $430 000 to further develop its physiological monitoring system. That’s on top of the $1 million the agency gave WPI in 2007 to combine its tracker with a system that measures vital signs.
Among candidates for a vital sign monitor are the sensor-studded shirt developed by Foster-Miller Inc. in nearby Waltham, Mass. It keeps tabs on the wearer’s posture, heart rate, respiration, and body temperature, and a wireless pulse oximeter, also developed at WPI, that’s worn on a band around the forehead (or eventually mounted inside a firefighter’s helmet). The oximeter measures oxygen in the blood as well as heart rate and respiration rate. The data can help predict the onset of a stress-related heart attack, the leading cause of firefighter deaths. Both versions were tested during the August exercise.