The dispatcher activates emergency traffic tones, then announces a collapse where firefighters have been trapped. Command adjusts tactics from suppression to rescue, placing attack lines or elevated streams in the collapse area to protect trapped firefighters from the advancing fire.

Prompt rescue of firefighters lost or down in burning buildings is critical. There's an extremely narrow window of survivability for firefighters out of SCBA air supply or trapped by approaching fire. Normally, rescuers attempt to determine the last known location of the lost firefighters by tracing hose lines, then looking for arms and legs, listening for shouts, taping noises, breathing, moans, radio broadcasts, audible tones from PASS devices, or the sounding of SCBA bells.

Now, a relatively new technology shows promise of adding an element of certainty to an otherwise uncertain rescue.

Downed firefighters

Orange County (Fla.) Fire and Rescue has completed initial field tests of a Global Positioning System — based rapid-deployment, in-building personnel geo-location and tracking system for use by firefighters on the fireground. The system is designed by MeshNetworks of Maitland, Fla., a mobile broadband networking firm, with systems integration assistance from IBM.

This Mesh Enable Architecture system, a spin-off of the company's sophisticated military battlefield geo-location solution, employs three or four routers mounted on 6-foot tripods positioned around the burning building. Once the routers obtain their exact latitude and longitude via GPS, they are able to perform wireless radio triangulation to fix the location of any firefighter within the perimeter who's equipped with a cell phone — sized transponder device.

“I don't want to raise hopes too much, but we found that fairly consistently we could identify what room of the building the firefighter was in and to consistently localize where he was to within 15 or 20 feet,” says Deputy Chief Bill Godfrey, Orange County Fire and Rescue Training and Information Technology Division. “From my perspective, that's a win. If you can take a space as large as a supermarket and land me within 20 feet of a down firefighter, I can find him with a thermal imaging camera.”

Thick smoke surrounding the routers was found not to be an issue, nor was hose-line operations. “With the frequency range this thing is using, you get some signal degradation like you would see from satellites during heavy rain, but that was not a factor in the testing we did,” Godfrey says. “That was one of the things we looked at, seeing if this thing worked with multiple hose streams.”

Potential pitfalls

While officials are encouraged by early results, a number of issues were exposed. For example, steel buildings were found to distort or inhibit signal clarity. High-rise buildings are another question. The system, which currently operates on a two-dimensional X — Y axis only — there is no Z or elevation axis — has yet to be tested in high-rise fire environments, although communications engineers are now looking at the feasibility of such operations.

In the future, it's conceivable that static geo-location router devices will be incorporated in the design of all new buildings and retrofitted into existing structures. It would be particularly useful in skyscrapers to have routers positioned at the corners of every floor, perhaps attached to every exit sign, yielding the ability to automatically track the location of all firefighters during a fire.

The Orange County tests also identified some issues with GPS accuracy on standard commercial GPS devices, Godfrey says. Civilian GPS can experience drift, limiting accuracy to plus or minus 50 — 60 feet. The accuracy of civilian GPS is limited by the Department of Defense, which controls the satellites and reserves the most accurate readings for military operations.

Another question is whether the router antennae eventually can be mounted on apparatus randomly dispersed at the scene instead of hand-positioned on tripods around the building, the inconvenient and cumbersome current method. Not only does it take personnel who would otherwise be used to attack the fire to position the tripods, but fences, buildings and other obstacles could conceivably inhibit prompt, proper positioning.

“Placing the routers on fire trucks is not feasible at this point, although MeshNetworks engineers are looking a different antenna configurations,” Godfrey says.

The antennae need to be appropriately positioned to complete the triangulation, and the best readings aren't from where fire engines typically are parked at the scene.

System evaluation is expected to continue to the next phase. Although high-rise capability adds a significant level of complexity, Orange County has nailed many of the X — Y single-story issues to make the system useful for fires at strip malls, as well as most homes and standalone stores.

“We've done the actual hands-on stuff, now we need to do the data analysis and make some decisions,” says Godfrey. “If we feel like this is worth pursuing, features such as high-rise operation and antenna placement are issues on the agenda to deal with.”

Resource tracking

Once GPS became accessible to civilians, novel uses for it soon followed. GPS applications quickly surfaced in rail and marine navigation, precision agriculture and mining, oil exploration, telecommunications, electronic data transfer, construction, and recreation.

Golfers use GPS to locate greens on golf courses, yielding exact distances, and spouses suspecting a partner of philandering stash handheld GPS units in vehicles to be retrieved later to re-trace where the device has been. Not surprisingly, a tool of such amazing utility was quick to find a use in the fire service.

Among the more useful GPS applications found by fire departments are geo-location and tracking of resources. A number of fire departments already have adopted GPS to geo-locate fire apparatus, water hydrants, storm drains and wildfire perimeters. The Milwaukee Fire Department, Anaheim (Calif.) Fire Department and El Paso (Texas) Fire Department, among others, have all recently joined the migration to GPS to provide state-of-the-art public safety systems, including real-time vehicle tracking and enhanced city mapping services.

These systems generally consist of a GIS/GPS-based vehicle tracking system and the associated mapping display software. GIS, or Geographic Information System, provides the mapping component. With the tracker devices installed in vehicles, dispatchers can follow a vehicle's location in real-time. When an incident occurs, controllers can quickly dispatch the vehicle nearest to the incident.

In the El Paso Fire Department, for instance, the GPS-powered automatic vehicle locator system tracks the location of the department's apparatus fleet. This system consists of a radio and a GPS receiver/transceiver affixed to each fire apparatus. A signal from the GPS unit is transmitted to a satellite, the signal bounces back to earth, and the radio system tells the computer system exactly where that unit is on a map to within one meter of accuracy.

The AVL computer then informs computer-aided dispatch which unit is closest. That's where the principal benefit, a decrease in incident response time, comes in. The department previously dispatched units based on the fire station closest to an incident. With this technology, it's able to send the closest unit available to take the call.

The Phoenix Fire Department, which includes fire and emergency medical dispatching services for 18 fire departments across the Valley of the Sun, also uses GPS technology for automatic vehicle location tracking to provide continual apparatus whereabouts, even while units are traveling, to ensure that the closest appropriate unit is dispatched. GPS is directly related to a decrease in response times in emergencies.

Wildfire perimeters

GPS is also a new asset for mapping the perimeters of wildfires, but there are problems. Walking the fire line with a GPS unit is too dangerous, and flying the perimeter in a helicopter equipped with GPS or mapping by hand from the air at a safe distance aren't often feasible. During the initial stages of a wildland fire, helicopters are usually busy with the more critical task of dropping water.

The Los Angeles County Fire Department has found a third alternative. It has equipped bulldozers with built-in GPS units, a scheme that's proved to be valuable because it takes the guesswork out of where a bulldozer line exists. The GPS receivers in these bulldozers have removable PC Type II cards that can be processed with associated mapping software. However, this bulldozer line typically makes up only a part of the fire line, the rest of which must still be mapped by other means.

Mapping by hand or heads-up digitizing from a good vantage point allows a GIS technical specialist to map the fire and see the surrounding terrain. Although this option isn't the most accurate or desirable, it's currently the fastest, safest method for getting decent maps into the hands of firefighters. Quick, accurate fire line maps are indispensable when allocating scarce resource while fighting wildfires, such as the October fire storms that devastated Southern California.

Obsolete paper maps

Mapping is one of the principal benefits of GPS technology, which promises to make paper maps in awkward three-ring binders obsolete. At the Newport Beach (Calif.) Fire Department, firefighters need only look at their in-vehicle computer screen to find the exact location of fire emergencies.

With mapping and routing software installed in each vehicle, fire captains who call out directions can instantaneously receive incident addresses and routing information from the computer-aided dispatch. The map automatically displays the quickest route and re-centers itself when the route goes off the computer screen. As the vehicles near the incident, captains can scan the map on the screen to find the locations of the nearest fire hydrants, as well as any potentially hazardous materials in the area.

Before GPS was installed, the station responding to a call would get a grid number and a street address from dispatch. Then the captain would flip through pages in the city map book searching for the location. Under the new system, the manual components of finding an incident address are eliminated.

Euless, Texas, a city of 44,000 midway between Dallas and Fort Worth, uses GPS to generate precise maps for locating fire hydrants within the city limits. Hydrant maintenance, a chore generally performed by the fire department, requires firefighters to periodically check the condition of every hydrant in the city. Sometimes they trim weeds, grease caps or exercise valves.

However, because not all hydrants appear accurately on department maps, the real purpose of the exercise is sometimes to familiarize firefighters with hydrant locations. Data collected by the system is fed into the fire department's preplan software to help with fire suppression scenarios. The data also is used by public works to identify hydrants that may be out of service for line repairs. That information is relayed to dispatchers so that the preplan scenarios can be updated automatically by fire department software.

“We've finished the GPS collection project for fire hydrants and have since GPS-ed storm drain inlets and about 20% of the water valves,” says David Allen, GIS manager for Euless. “Our storm drain maps were generated for a Governmental Accounting Standards Board statement but are useful to the fire department in containing chemical spills.”

Another benefit: Firefighters no longer have to GPS-locate hydrants. “I typically go out and GPS the new ones as they are installed,” Allen says. “Since this is only a few each month, it is easy for me to keep the maps current.”

Mayfield (N.Y.) Fire District #2 has found several other uses for its GPS system. “We're using GPS technology everywhere we can,” says Chief Myron Messak. “We've implemented predetermined trauma helicopter landing zones, not only in my fire district but for all fire districts in county.”

Messak's agency also has developed GPS maps of all village buildings and hydrants, mapped the location of rural water sources and dry hydrants. “We even have a hotlink of buildings on the map to an AutoCAD floor plan to help in the event of a fire,” he says.

GPS at Ground Zero

GPS was instrumental in documenting the location of items recovered at Ground Zero. FDNY, which had been charged with the task, realized soon after the Sept. 11 attack that recovery workers were having trouble recording evidence locations.

Firefighters had to sight landmarks to gauge where they were within the 16-acre site, which was broken into 75- by 75-foot blocks for mapping. They then took notes on paper indicating what was found — whether metal fragments or human remains — and approximately where before the item was removed to a landfill, warehouse or the medical examiner's office. The information later was entered into a computer database by hand.

Sensing a better technique was needed, FDNY officials met with a few technology companies to come up with a more accurate solution, which turned out to be handheld GPS units that automatically recorded the location of recovered items with an accuracy within 3 to 9 feet. The data then was transferred to nearby laptops connected to a database.

Ironically, GPS, which relies on satellite line-of-sight to pinpoint a location, generally does not work well in Manhattan because of the canyon effect created by the city's skyscrapers. However, the large space left by the collapse of the twin World Trade towers opened the skyline so the devices could connect to the satellites.

From finding downed firefighters to digging out hydrants after a blizzard, GPS and its frequent companion GIS can serve many uses for the average fire department. As prices continue to drop, it will be harder to justify not having access to the refined locating and mapping abilities that every department needs.

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Douglas Page, Fire Chief's technology correspondent, is a freelance writer based in Pine Mountain, Calif.

GPS Satellites

The current GPS constellation consists of 28 Block II/IIA/IIR operating in circular 10,900nm (20,200km) 12-hour orbits at an inclination of 55 degrees. They are not in geo-stationary orbit.

What, Why, How

Worldwide radio-navigation GPS is possible due to a constellation of 24 orbiting satellites (plus three spares) and associated ground receivers.

Terrestrial GPS receivers use the satellites as reference points to calculate positions accurate to a matter of feet. Advanced forms of GPS used by the military are accurate to less than an inch. Civilian GPS, previously accurate only to 100 yards, was improved ten-fold in May 2000, when President Bill Clinton ordered the U.S. military to stop intentionally degrading the satellite signals used by civilians. Now GPS essentially gives every square foot on the planet a unique address.

One fundamental limitation of GPS is that receivers require an unobstructed view of the sky, so they only can be used outdoors. Even then, they often don't operate well within forested areas or near tall buildings. GPS operations also depend on an accurate time reference, which is provided by atomic clocks at the U.S. Naval Observatory. Each GPS satellite has atomic clocks on board.

Thus, each GPS satellite transmits data indicating its present location and the current time. All GPS satellites synchronize operations so that these repeating signals are transmitted at the same instant. The signals, moving at the speed of light, arrive at a GPS receiver on the ground at slightly different times because some satellites are farther away than others.

Distance to the GPS satellites can be determined by estimating the amount of time it takes for their signals to reach the receiver. When the receiver estimates the distance to at least four GPS satellites, it can calculate its position in three dimension.

GPS receivers have been miniaturized in recent years. Hand receivers with just a few integrated circuits are now available starting at $100, permitting widespread civilian use.

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