Thermal: A New Pillar of Bridge Security

Bridges make up an essential component of the U.S. transportation infrastructure, as well as the economy of the country as a whole. A bridge is often the only way to cross a particular area or waterway, and any disruption has the potential to greatly impact the flow of commerce and create serious safety hazards. Given their importance, it is crucial that these valuable assets are highly secured to prevent incidents from occurring.

Bridges have a unique set of requirements, making them more challenging structures to secure and protect. Bridge applications are typically installed by an integrator that has experience and expertise in intelligent traffic and/or video security systems. These integrators have deep knowledge of the critical transportation infrastructure and know how best to address challenges with sourcing and installing equipment to mitigate the effects of environmental and other factors that could affect performance.

The Unique Challenges

Most outdoor security applications involve clearly defined interior and perimeter areas, normally separated by a fence or other barrier. This definition makes it clear where people are not allowed to go. Should an intruder cross a fence or other perimeter barrier, authorities, when properly alerted, can investigate and take action.

With bridges, however, this simply is not possible. At minimum, the roadway or railroad track has to remain open to allow traffic flow. Without a clear delineation, there is no real concept of whether an individual or vehicle should be in a particular spot with regard to a bridge — or even where the line of demarcation between acceptable and unacceptable areas should be drawn. As a result, bridges are by their nature exposed from all sides, making them vulnerable to incidents, accidents and transportation issues from above, below and at street or railway level. Further complicating the matter is that traffic, either by road or water, often needs to pass under bridges throughout the normal course of the day and night.

Security Solutions

Potential solutions could involve setting up a virtual trip-line with an infrared beam that generates an alert if and when a secured area is violated. The problem is that these solutions by themselves can be circumvented by someone simply crawling under or climbing over the “virtual fence” they create. These systems can also trigger many nuisance alerts due to the difficult environment, so security personnel eventually ignore the alarms.

Another solution in the past has been to use video surveillance cameras, but experience proves that guards quickly tire when staring at monitors and may miss an intrusion when it occurs.

A robust thermal security solution, on the other hand, combines thermal cameras with video analytics to stop and detect intrusions automatically. These systems can be used to create a virtual buffer zone of security above, below and from all sides of a structure, sending alarms the instant violations occur. By sensing heat rather than visible light, they are a perfect human detector in bright sun and complete darkness without requiring additional lighting. On-board image processing is used to ignore headlights, reflections off water, as well as the movement of small animals, trees or blowing trash while accurately detecting the presence of unauthorized persons anywhere across site perimeters, enclaves and isolated areas.

Thermal Gets Smarter

Benefiting from the same processing advancements that make many devices so powerful, today’s smart thermal cameras employ a high degree of processing to amplify small differences between the temperature of an intruder and the background, accurately detecting targets even in difficult  conditions. Integrated GPS technology is used to determine the size and speed of objects over large distances, minimizing nuisance alerts while providing critical information about an intrusion’s location. Once an intrusion has been detected and assessed by a thermal camera, visual PTZ cameras can be automatically steered and zoomed to provide further information if it is needed.

Smart thermal detection systems are particularly well suited for the unique security applications needed for a bridge environment. For example, they can be deployed to monitor boat traffic passing beneath a bridge and generate an alert only if a vessel stops or is tied to that structure in violation of an established policy. Such an automated system can detect and then broadcast an audible message to inform the individual that they are in an unauthorized area. If he or she has no malicious intent, this is often enough for them to move their boat to an acceptable location; however, if the craft remains in place, the response can be escalated to the next level.

A similar scenario can also be applied to bridge surfaces where individuals might attempt to climb to the top of the structure or enter the roadway or railway from the pedestrian path. With a clearly defined “virtual” protection area in place, it is possible to use the video analytics built into cameras to set up specific rules for detection based on object size or speed, time of day, location and other factors. Such geospatial rules can be used to alert security personnel when a car has stopped on the roadway, which is critically important when there is little shoulder room; they can also be used to detect a vehicle traveling the wrong way across a bridge, and flash messages to warn drives instantly.

Because of the especially challenging nature of bridges, some systems offer additional capabilities that help to mitigate the effects of the environment. For instance, smart cameras are designed to detect movement, but bridges experience a high degree of movement from wind and vibrations from passing cars or trains. For this reason, some smart thermal security systems employ electronic stabilization which eliminates camera shake from causing alerts, a necessity for reducing false positives in a bridge application.

In many cases, a bridge is used to span a waterway, which creates an environment where there is typically higher humidity and potential for fog; for this reason, some thermal systems are nitrogen-purged and pressurized to keep moisture from impacting the camera electronics and maintain a high degree of detection accuracy.

Smart thermal video systems have proven highly effective in securing bridges, but installing and deploying them on a bridge can be different from other types of outdoor integrations. Users will look for an integrator with experience dealing with bridge-specific issues from camera placement to dealing with environmental challenges, and the ability to successfully deploy a video system on a bridge gives these integrators a unique advantage.

At the end of the day, the goal of securing bridges is to provide the high level of security they require as vital components of transportation systems. A thermal video security system provides this capability, allowing for more accurate detection based on specific types of objects, events and other important criteria. With these zones established, smart cameras make it possible to secure access to bridges and their surrounding areas. The result is heightened security that won’t interfere with the normal function on and around bridges.

John Romanowich is CEO of SightLogix Inc. To request more information about the company, please visit www.securityinfowatch.com/10215746.