USAR: How radar tech can help canines find trapped victims
Ultra-wide band radar is one more tool rescuers can use to pinpoint survivors buried in rubble
On any given day, there are urban search and rescue operations going on somewhere around the globe. The mechanisms can include both natural – earthquakes, floods and tsunamis, mudslides and avalanches – as well as man-made events like bombings.
Regardless of the mechanism, disasters that include multiple or multi-story collapsed structures are chaotic and noisy. Rescuers are faced with the challenge of searching for potential survivors who may be trapped under tons of concrete and steel. And they’re working against the clock.
For a long time, highly trained search-and-rescue dogs have been at the forefront of USAR technology. These special canines with their incredible sense of smell have proven themselves time and again to be lifesavers, as they’ve assisted their human counterparts to locate survivors.
USAR-trained dogs, when assisted with other technologies like borehole cameras, provide an effective set of search tools for USAR teams.
I’ve always been fascinated by rescue dogs. Those specially trained canines are quick and can effectively cover large geographical areas and they’re able to work remotely from their handler.
On the downside, USAR dogs cannot determine the distance to an entrapped survivor, and their keen sense of smell can be affected by scent drift during windy conditions.
They are also not machines. Like their human handlers, they are also susceptible to fatigue and stress and require downtime to recuperate. They can also suffer physical injuries such as strains, sprains and fractures, as well as environmental injuries like heat exhaustion and heat stroke.
Two USAR technologies
USAR teams have been using two technologies to complement their search canines when attempting to locate structural collapse survivors: borehole cameras and acoustic vibration monitoring devices.
Each method has its advantages and disadvantages. For those who may be unfamiliar with these tools, here is a quick overview.
Acoustic vibration monitoring devices (AVMDs) can be placed by a rescue team atop a rubble pile to listen for sounds from a survivor, like tapping, yelling, kicking or other noises.
While AVMDs can be very effective, these devices require a high level of user expertise; they also require almost complete silence. That’s not the typical environment found at the scene of a structural collapse.
The greatest disadvantage for AVMDs is that they require active participation by a survivor. If the survivor is incapacitated, unconscious or otherwise incapable to make noises, the AVMD has nothing to work with.
Borehole cameras are lightweight devices that contain a small camera, flashlight and microphone. This combination enables the rescuer to establish two-way communication with a trapped survivor.
However, many borehole cameras have a limited depth of penetration, typically 10 to 13 feet. Another significant drawback is that they require direct line-of-sight between the rescuer and the survivor through an opening of some kind in the rubble pile, which is not always available.
Ultra-wide band radar
Ultra-wide band (UWB) radar for USAR operations is the newest search technology that provides rescuers with the ability to detect very fine and immediate motions from a survivor.
UWB radar can detect both irregular movements, such as hand or finger movement, or regular movements, such as chest movements from breathing.
UWB radar technology interrogates the sub-surface of rubble and can provide a victim’s location at distances up to 100 feet in free space. The radar sends out 800,000 pulses per second while measuring the two-way transit time between the unit and the survivor.
UWB radar is also safe. The radar energy emitted is equal to one-hundredth of the power emitted by the typical wireless phone.
The application of such UWB radar technology is not new; it’s been widely used for automotive collision-detection systems, wireless communications, indoor positioning and sensor networks.
Developers have adapted UWB radar for USAR scenarios because it provides a wider band of radar detection, and is less susceptible to interference than narrow band radar. Narrow band radar provides poor down-range resolution and lacks the ability to accurately determine the distance to the victim.
UWB radar and canines
When used in conjunction with USAR-trained canines, UWB radar provides rescuers with a very effective search and rescue package. A typical scenario might look like this.
A USAR team with their canine quickly works across a predetermined grid atop a rubble pile at a collapsed structure. The dog gets a hit indicating the presence of a potential survivor, but cannot indicate if the survivor is 3, 6 or 12 feet away. This is where the rescue team member applies the UWB radar device, which can determine the approximate distance to the survivor.
UWB is also a good tool for determining where not to dig. This is important when working a rubble pile where rescuers are likely dealing with tons of unstable concrete and steel.
Because UWB radar depends upon motion from a survivor, either irregular or regular, it cannot detect the deceased. UWB radar also cannot see through metal, and is susceptible to noise interference from cell towers or radio communication systems.
There are at least three prominent manufacturers making UWB radar device for USAR operations.