Knowledge Resources

The iFlorida Bridge Security Monitoring System consisted of a software and hardware system that automatically monitored video images of the bridge and its vicinity and activated an alarm whenever suspicious activities might be occurring near the bridges. When an alarm was activated, the system would allow operators to review real-time and archived video footage to identify the source of the alarm and then mobilize and monitor response activities, if a response was required. Before deciding to deploy a Bridge Security Monitoring System, the FDOT performed a review of the security risks to identify the highest priority risks that could be addressed most cost effectively. The applicable parts of the Homeland Security Comprehensive Assessment Model (HLS-CAM), developed by the National Domestic Preparedness Coalition, was used in order to gather information on the costs and effectiveness of such a system. The security monitoring system was deployed at two bridges. In the process of deploying and using the system, the FDOT identified several lessons learned that might benefit others wishing to deploy similar systems:

• Perform adequate tests to calibrate and validate the capabilities of a bridge monitoring system. Many different types of tests were available for FDOT to use to detect threats and sound alarms. While the software made these tests easy to define, it was difficult to define them in such a way that reduces the number of false alarms. Special expertise, if not available at the DOT, must be hired to perform the specialized calibration, testing, and validation.
• Ensure that the number of false alarms is not excessive. The high number of false alarms in the iFlorida Bridge Security Monitoring System meant that alarms were often ignored. Testing the number of false alarms, and adjusting the system until an acceptable number was generated, might have made the system operators more responsive to alarms that did occur.
• Provide provisions for adjusting the alarm plan during special circumstances, such as construction activities or the presence of a disabled vehicle. The operators at the District 5 RTMC noted that a number of common events, such as construction activities or a disabled vehicle on the bridge, would sometimes generate a large number of false alarms. The system did not include a convenient way to adjust the operating parameters when such situations occurred.
• Conduct a cost effectiveness analysis. The FDOT demonstrated that a video monitoring system could be used to identify potential threats to a bridge provided the false alarms can be brought to an acceptable level. However, the cost of monitoring the two bridges was high—more than $860,000 for design, deployment, and two years of operation. Since the likelihood of attack at these specific bridges was relatively low, a complete HLS-CAM review would likely have identified more cost-effective ways to increase transportation security.
• Locate the video processing and archiving equipment away from the bridge or the asset being protected, preferably in a climate-controlled environment. The FDOT noted that, with the video archiving hardware deployed in the field, a catastrophe at the bridge would likely destroy the archived video. Archiving the video at a location separate from the monitored asset would protect the archived video from damage, so that it could be used to support post-catastrophe analyses. The FDOT also believed that the equipment deployed in the field would have operated more reliably if deployed at the climate controlled environment of the Deland office.

The effectiveness of the Florida’s bridge security monitoring system was compromised by the occurrence of high number of false alarms. In a security operations center with operators devoting full-time attention to video surveillance, such false alarms could be easily dismissed by operators and might be a minor nuisance. At the District 5 RTMC, however, operators were primarily concerned with traffic operations and could not review and dismiss frequent bridge security alarms. In this type of environment, the acceptable number of false alarms is low. Given the uncontrolled environment around most bridges, it was not clear whether existing video analysis systems could provide a low enough level of false alarms to make the system useful without having full-time operators available to discount false alarms.