Security Strategies
The committee that addressed security strategies concluded that the prospects for defending against each of the vulnerabilities of the transportation system through traditional means, or "guards, guns, and gates," are dim (Special Report 270: Deterrence, Protection, and Preparation: The New Transportation Security Imperative; TRB 2002). The transportation sector is simply too large and the threats faced too diverse and inconstant for such blanket approaches to work. Moreover, if applied in the large and diffuse transportation sector, these approaches run the risk of creating a diluted and patchwork collection of poorly connected defenses that disperse security resources while leaving many vulnerabilities unprotected against a terrorist attack.
Transportation security can best be achieved, concluded the committee, through coherent security systems that are well integrated with transportation operations and deliberately designed for deterrence even as they selectively guard against and prepare for terrorist attacks. In particular, layered security systems, characterized by an interleaved and concentric set of security features, have the greatest potential to deter and protect. Layered systems cannot be breached by the defeat of a single security feature—such as a gate or guard—because each layer provides backup for the others so that impermeability of individual layers is not required. Moreover, the interleaved layers can confound the would-be terrorist. Calculating the odds of breaching a multitiered system of defense is far more difficult than calculating the odds of defeating a single, perimeter protection.
The committee found that when integrated well with transportation services and functions that confer other benefits, such as enhanced safety and service quality, layered systems are even more likely to be deployed and sustained over time. Multiuse systems—for instance, systems that benefit transportation operators and users by monitoring the condition of infrastructure and location of vehicles, baggage, and cargoes—are apt to be maintained and continually adapted to the changing transportation environment. A combination of public leadership and private incentives is therefore essential to the deployment of such dynamic, built-in security systems.