Protecting the Bravest

New technologies under development can be used to help locate firefighters in burning buildings and determine whether they are in distress.

When firefighters enter a burning building, the risk of injury and worse comes in myriad forms. In addition to being at risk from heat, smoke, and structural failures, firefighters are under constant threat of becoming lost in structures—not only disoriented but also off the radar with their commanders, who are unaware of their whereabouts and unable to communicate via radio through heavy building walls and facades.

Another serious threat, less well known but not surprising given the nature of their work, is that close to half of all on-duty firefighter deaths result from heart attacks, with roughly three-quarters of them occurring on-scene, according to U.S. Fire Administration and Harvard University research.

Now the private sector, academia, and the federal government are collaborating to integrate two emerging technologies—non-GPS location tracking and wireless physiological sensors—to both follow first responders and spot physical warning signs in real time.

For faculty at Massachusetts’ Worcester Polytechnic Institute (WPI), the issue hits close to home. Six city firefighters died in the December 1999 Worcester Cold Storage Warehouse fire after they became disoriented in the smoke-filled structure and their air supplies ran out. The tragedy spawned a research initiative at WPI aimed at developing precision indoor location tracking technology.

GPS does not meet this need for two primary reasons: reception and accuracy. GPS receivers must acquire signals from four satellites to produce an ideal fix, which is difficult to impossible inside most buildings. Even when it can be achieved, GPS accuracy is good only to within a few meters, and that is not even sufficient for determining which floor of a building a firefighter is on.

To find an alternative, WPI developed a system based on traditional radio signals transmitted from small units attached to firefighters’ turnout gear. Simple triangulation, however, would not work, because most radio signals that do make it out of a building have bounced off interior walls. “This ‘house of mirrors’ effect is what makes the numbers you get so unreliable,” says Dave Cyganski, who is developing the technology with fellow WPI faculty members.

To distill an accurate location from the jumble, WPI researchers have adopted algorithms used in two other detection technologies—synthetic aperture radar and computed tomography (CT) scanners—both of which develop images from multiple antennas or sensors. In the case of WPI’s application, an array of receivers, each about the size of a briefcase, would first have to be positioned around a structure when crews arrived at a scene. The WPI location tool is, however, “not ready for prime time,” developer James Duckworth says, noting that it must produce reliable data before it’s handed to firefighters, as even slightly inaccurate location data “can actually make a situation worse.”

A separate location tracking technology, however, is already being deployed. Developed by TRX Systems, it is called TRX Sentrix. This system also relies on a small unit carried by the user, but it starts with a known GPS-based location determined before entering a structure. Sensors inside the unit—including a gyroscope, accelerometer, and an altimeter—track movement from that point and transmit it to commanders.

When Security Management first wrote about this technology in October 2008 (See “A Burning Issue: How to Save Lives”), the developers were trying to find a way to mitigate errors that compounded as the sensor moved farther from its initial waypoint. Now, TRX CEO Carol Politi says that smarter sensors have solved the problem.

The new sensor software can detect specific types of motion based on accelerometer readings, such as walking, sidestepping, or crawling. Further, long-distance ranging can measure the distance between wearers or from base stations, Politi says. The company now offers a three-dimensional rendering interface that can “build” maps as users move through a structure, or can superimpose their movements in computerized building plans or in open-source exterior models like Google Maps.

Both developers—WPI and TRX—are integrating physiological monitors with their systems. WPI has tested pulse sensors fixed to headbands that can measure a firefighter’s pulse rate, temperature, and blood oxygen content, displaying the readings alongside location dots on commanders’ computer displays.

TRX has teamed with monitor manufacturer Zephyr Technology. Zephyr’s monitors measure heart rate, respiration, skin temperature, and body orientation. Another partner, Globe Firefighter Suits, will integrate the monitor into garments.

The Zephyr monitors communicate via Bluetooth technology with wearers’ radios, transmitting data to a commander’s computer. Information on a user’s age, height, and weight can be used to set color-coded stress zones for each wearer with alarms, explains spokesman Asher Gendelman. The hope is that these systems will keep firefighters and their lives from being lost.