The nation’s transportation system is a vast, interconnected network of diverse modes. Key modes of transportation include aviation; highways; motor carrier (trucking); motor coach (intercity bus); maritime; pipeline; rail (passenger and freight); and transit (buses, subways, ferry boats, and light rail). The nation’s transportation systems are inherently open environments, designed to move people and commerce quickly to their destinations. For example, the nation’s transportation system moves over 30 million tons of freight and provides approximately 1.1 billion passenger trips each day. The diversity and size of the transportation system make it vital to our economy and national security. TSA is responsible for the security of all modes of transportation, as outlined in the Aviation and Transportation Security Act (ATSA) (Pub. L. No. 107-71). Following the passage of ATSA, TSA began addressing two major challenges—procuring and installing explosives detection systems (EDS) and explosive trace detection (ETD) systems to screen checked baggage for explosives, and hiring and deploying federal screeners to screen passengers and their baggage at commercial airports nationwide. TSA is also tasked with managing security risks to surface transportation systems. These systems include 9 billion passenger trips per year on the nation’s mass transit systems, over 161,000 miles of interstate and national highways and their integrated bridges and tunnels, and nearly 800,000 shipments of hazardous materials. Given the vast transportation network, quick and easy access for passengers and cargo must be maintained while identifying the best possible strategies for security. The President’s fiscal year 2006 budget request recognizes the need for TSA to identify, prioritize, and manage risks, and mitigate the impact of potential incidents, to help ensure that the best strategies are pursued. Consistent with this goal, GAO has advocated the need to implement—at TSA and throughout the federal government—a risk management approach for prioritizing efforts and focusing resources. A risk management approach entails a continuous process of managing risk through a series of actions, including setting strategic goals and objectives, assessing risk, evaluating alternatives, selecting initiatives to undertake, and implementing and monitoring those initiatives. Assessing risk, a critical component of a risk management approach, involves three key elements—threats, vulnerabilities, and criticality—that provide input into the decision-making process. A threat assessment identifies and evaluates potential threats on the basis of factors such as capabilities, intentions, and past activities. A vulnerability assessment identifies weaknesses that may be exploited by identified threats and suggests options to address those weaknesses. A criticality assessment evaluates and prioritizes assets and functions in terms of specific criteria, such as their importance to public safety and the economy, as a basis for identifying which structures or processes are relatively more important to protect from attack. Information from these three assessments can lead to a risk characterization, such as high, medium, or low, and provides input for prioritizing security initiatives. Figure 1 depicts a risk management cycle. In addressing security needs and challenges for all transportation modes, the President’s fiscal year 2006 budget request categorizes TSA activities into three main areas: (1) Aviation Security, (2) Surface Transportation Security, and (3) Transportation Security Support. Each of these areas is summarized in detail below and the total funds requested are presented in in table 1 that follows the summary. Aviation security includes two distinct decision units: screening workforce and equipment, and aviation direction and enforcement. Screening workforce and equipment includes funding to support passenger and baggage screener activities such as screener salaries and training, and the purchase and installation of screening equipment. Aviation direction and enforcement includes regulation compliance for air cargo, airports, and airlines through inspections and other efforts, and airport technology activities and administrative support. The budget requests about $5 billion for the aviation security appropriation for fiscal year 2006. These funds will support the current federalized and privatized screener workforce, provide training and other support for both passenger and baggage screening, and continue other aviation security regulation and enforcement activities. Increases were requested for, among other things, the screener workforce, checkpoint explosive detection technology, and high-speed information technology connectivity. The budget request further identified the mandatory $250 million appropriation of the Aviation Security Capital Fund to assist in the purchase, installation, and/or integration of EDS and ETD systems. At these levels, TSA expects to maintain current security and wait time performance at over 430 commercial airports. Surface transportation security includes resources for TSA’s security operations in all non-aviation modes of transportation. Such operations include developing standards and regulations to protect the transportation infrastructure; conducting inspections to monitor and enforce compliance with standards and regulations; designing and implementing vulnerability assessment models for all surface transportation modes; and facilitating information sharing with transportation stakeholders. The budget requests $32 million for surface transportation security in fiscal year 2006. These funds will be used to maintain TSA’s various surface transportation security initiatives, including surface transportation inspectors added during fiscal year 2005. Transportation security support includes funding for the operational needs of TSA’s airport and field personnel and infrastructure. This area also supports TSA headquarters and the Transportation Security Intelligence Service. Although R&D funds are also included in this appropriation, the President’s fiscal year 2006 budget request proposes that these funds be transferred to the DHS Science and Technology Directorate. The budget requests $545 million for transportation security support for fiscal year 2006. These funds will be used to help ensure that TSA screeners and other operational employees have sufficient intelligence information, information technology, management direction, administrative services, and other key support to accomplish the agency’s mission. TSA has taken numerous steps to strengthen aviation and surface transportation security and should be commended for its efforts. However, better planning is needed to help ensure that these initiatives are focused on the areas of greatest need to assist TSA in achieving efficiencies and enhancing security. For example, since September 11, for example, TSA has (1) installed EDS and ETD systems at most of the nation’s commercial airports to provide the capability to screen all checked baggage using explosive detection systems, (2) expanded screener training and developed performance measures and indicators for the screening systems, (3) developed an air cargo strategic plan, and (4) evaluated the security of airport perimeters and access controls and provided funds for security equipment. Despite these efforts, however, we have consistently found—because of circumstances beyond TSA’s control and a lack of planning—that TSA has not conducted the systematic analysis needed to inform its decision-making processes and to prioritize security enhancements. For example, we found that TSA has not always conducted needed assessments of threats, vulnerabilities, and criticality in allocating its resources, and has not fully assessed alternatives that could be pursued to achieve efficiencies and potentially enhance security. Such planning could guide TSA in moving forward in its allocation of transportation security funding and assist it in making wise investment decisions while enhancing the security of all transportation modes. In February 2005, we reported that TSA had installed EDS and ETD systems at most of the nation’s more than 400 commercial airports to provide the capability to screen all checked baggage using explosive detection systems, as mandated by Congress. Despite these efforts, however, we found that in moving forward, TSA had not conducted the systematic planning needed to optimize the deployment of these systems—in particular determining at which airports EDS machines should be integrated in-line with airport baggage conveyor systems to achieve efficiencies. Such planning is important for TSA to be able to ensure that it is efficiently allocating its limited resources to maximize the effectiveness of its checked baggage screening operations and is achieving desired results. From its creation in November 2001 through September 2004, TSA obligated about $2.5 billion (93 percent) of the approximately $2.7 billion it had budgeted for fiscal years 2002 through 2004 for procuring and installing explosive detection equipment—predominantly to screen checked baggage for explosives—and making associated airport modifications to accommodate the equipment. Specifically, TSA procured and placed about 1,200 EDS machines and about 6,000 ETD machines at over 400 airports, and modified airports for the installation of this equipment. Given the congressional mandate to screen all checked baggage using explosive detection systems by December 31, 2002, later extended to December 31, 2003, TSA worked with a contractor to quickly deploy EDS and ETD equipment to the nation’s airports. This response resulted in TSA placing stand-alone ETD and the minivan-sized EDS machines—usually in airport lobbies—that were not integrated in-line with airport baggage conveyor systems. Some of these interim lobby solutions resulted in operational inefficiencies, including requiring a greater number of screeners, as compared with using EDS machines in- line with baggage conveyor systems. Also, screening solely with ETD machines is more labor intensive and less efficient than screening using the EDS process. TSA officials stated that they used EDS machines in a stand-alone mode and ETD machines as an interim solution in order to meet the congressional deadline for screening all checked baggage for explosives. Officials further stated that they employed these interim solutions because of the significant costs required to install in-line systems and the need to reconfigure many airports’ baggage conveyor systems to accommodate the equipment. While in-line EDS baggage screening systems have a number of potential benefits, including streamlining airport and TSA operations and reducing screenings costs, these systems are capital-intensive because they often require significant airport modifications, including terminal reconfigurations, new conveyor belt systems, and electrical upgrades. Since the initial deployment of EDS and ETD equipment, TSA has not conducted a systematic analysis of cost savings and other benefits that could be achieved from the installation of in-line baggage screening systems.