Fall  >>  2005

Improving Surface Transportation Security

The Role of Geospatial Technologies in Intermodal Freight and Hazardous Materials Transport

Ray A. Williamson
Research Professor Space Policy Institute
of The George Washington University
Washington, D.C.
Amelia Budge
Clearinghouse Manager
Earth Data Analysis Center
University of New Mexico
Albuquerque, New Mexico

The effects of the frightening terrorist attacks on the United States on Sept. 11, 2001, reached far and deep into American society and beyond. Since then, virtually every organization throughout the world has confronted the question of how it can improve security and resilience to terrorist attack. The recent social disruption and extreme damage from hurricanes Katrina and Rita raise related questions for planning for and response to natural disasters.

Transportation security is, of course, of highest concern not only because breaches in airline security allowed the Sept. 11 terrorists to use civil aircraft as high-energy weapons, but also because vulnerabilities throughout the surface transportation system make many elements of the transportation infrastructure potential targets of terrorist activity. Intermodal freight transport and the surface transport of hazardous materials are of particular concern to transportation officials.

The safety and security of surface transportation (including subway transit) have gained additional salience since the coordinated July 7 bombing of three subway trains and one bus in London. U.S. transportation offi- cials and policymakers are specifically addressing the important question of what needs to be done to strengthen security for the country’s surface transportation systems, systems that are particularly vulnerable to attack.

Remote sensing, geographic information systems (GIS), position, navigation, and timing (PNT) and other geospatial technologies provide powerful tools for dealing with these important security concerns. To aid in focusing research and development efforts, the R&D community needs to hear from state and local officials about their specific needs and concerns. This article summarizes the efforts of the Consortium for Safety, Hazards, and Disaster Assessment of the National Consortia for Remote Sensing in Transportation (NCRST-H) to develop a workable agenda for research, development, testing, and implementation of geospatial tools to improve transportation security. Although its recommendations are targeted specifically for implementation in the United States, most of them can be applied throughout the world.

The Transportation Security Challenge

Protecting America’s many different transportation components from attack or from being used to attack other elements of U.S. critical infrastructure is a daunting task. Included are: 4 million miles of roads, 500,000 bridges, 150,000 rail track miles, 5,500 public use airports, 25,000 miles of waterways, 1.6 million pipeline miles, and 5 million containers traveling through U.S. ports per year.

Intermodal transport poses a special challenge to transportation security because freight containers generally travel long distances and may change transportation mode several times in passing from supplier to customer, allowing intervention from terrorist elements. Some five million containerized freight shipments move through America’s ports each year, creating a signifi- cant challenge to security personnel at all levels. After arriving on U.S. shores from myriad other countries, the containers are loaded onto trucks and rail cars and shipped throughout the U.S.

Hazardous materials pose their own challenges. Some of the more common and familiar transport items that move through thousands of urban centers daily pose extraordinary risks to security, including:

  1. Chlorine (45,000 rail shipments of chlorine annually)
  2. anhydrous ammonia
  3. Gasoline (50,000 truck shipments of gasoline daily)
  4. Propane Gas
  5. Explosives (125,000 truck shipments of explosives annually)
  6. Radioactive Materials

Geospatial experts can take information developed by experts in terrorist methods and use geospatial technologies to explore a variety of possible terrorist scenarios. Modern analytic and display software allows rapid processing of possible geographic approaches in three dimensions and helps analysts discover infrastructure vulnerabilities that may not be immediately apparent to the eye, even to individuals familiar with an area.

Remotely sensed imagery, especially that from high resolution commercial satellites and digital sensors aboard aircraft, can assist in surveying and monitoring conditions around critical infrastructure. In combination with other geospatial tools, imagery can then be used to assist in mitigating the effects of any possible future terrorist incident. Recent research by Imagecat, Inc. has shown that for hurricanes and earthquake damage, high resolution imagery delivered immediately after a natural disaster may be crucial in assessing damage and mapping areas most in need of ameliorative response. One need only have watched any news broadcast to see the utility of aerial and satellite imagery for assessing damage following the devastating Hurricane Katrina in the U.S. Gulf Coast region. Similar assessment tools can be used in case of a successful attack to guide response teams in the field. Indeed, the experience of the country’s uncoordinated response to this damaging natural event should prove extremely helpful in designing and implementing improved planning and response methods.

improving Intermodal and Hazardous Materials Transport Security

Intermodal and hazardous materials transport are closely interlinked, and many of the security issues faced in each are similar or overlapping. For example, hazardous materials often travel by the same or similar intermodal routes required for the transport of nonhazardous materials. Nevertheless, the security issues for each also differ. For intermodal transport in general, security concerns tend to focus on whether or not terrorists are bringing destructive chemical, biological, or nuclear materials into the country covertly. In the case of commonly transported hazardous materials, security interests tend to focus on keeping close track of the materials along their routes.

Intermodal Transport

The logistical complexities of intermodal or multimodal transport make this sprawling component of the transportation industry extremely difficult to secure. It will be imperative to integrate information management tools, such as databases and statistical analyses, with geospatial technologies to increase the overall effectiveness of protection strategies. Needed is a suite of tools, including: advanced cargo shipping information, automated manifest interface, advanced profiling, and vulnerability and risk assessment tools. Systems for automated identification and communication of high-risk cargo are also needed.

Figure 1 << Infrastructure elements in the Port of Savannah, Ga. Oblique digital imagery with embedded GPS positions make possible a new level of remote sensing analysis, including the capability to see under bridges. The images are captured from opposite sides of the bridge and displayed at different scales. The red crosses in each image mark the same point along the rail section. Image courtesy of Pictometry, Inc.

Figure 2 << Attack scenario of the Port of Savannah, Ga. with digital oblique imagery and embedded GPS positions. This is a model of a chemical plume released by an attack, incorporating wind patterns.

Multispectral and SAR imagery can be used to monitor and analyze the areas around ports, rail facilities, and trucking terminals to assure that they remain as secure as possible from attack. Active multispectral sensors capable of monitoring the local atmosphere around these facilities can test for chemical and biological agents. Digital video from near-ground platforms (e.g., towers, tethered balloons) and aircraft can be used in real-time to assure that an area remains secure, particularly while loading and unloading container ships. Information from these digital video images can be merged with other information to form extremely powerful analytic tools both for real-time and historical analysis.

Securing Hazardous Materials Transport

The transport of hazardous materials requires special attention because the materials themselves pose particular health and safety hazards, regardless of terrorist concerns. The sheer volume of hazardous materials transported every day through towns and cities increases the difficulty of tracking them. Geospatial tools, combined with advanced communications technologies, can ease this burden and provide better quality information for security officials.

Among other things, geospatial tools such as mobile mapping and temporal change detection allow users to speed up the production and even automate many tasks now carried out by hand. If properly developed and tested, these tools can provide precise position information and more details about the environs of the transported material. For example, if a shipment is attacked or communication is lost, highly detailed, image-based maps of the route can help authorities answer such questions as: What is the physical environment in the area of last communication? What is the quickest route to reach the area?

Integrating Geospatial Technologies into Transportation Security Systems

Geospatial technologies can assist in improving the security of roads and highways, rail transportation, and ports for both intermodal and hazardous materials transport.

Roads and Highways

Geospatial technologies are particularly powerful in analyzing vulnerabilities in highway infrastructure elements and reducing their exposure to attack, or to congestion in rapid area evacuations. For example, they offer a vast improvement in speed, accuracy, and repeatability over manual methods such as “windshield surveys” in which two individuals drive the route taking notes on the factors that could affect route security.

Combining such manual methods with modeling software would enable the development of a hierarchical set of decision support tools capable of assisting transportation managers to select routes and risk-reduction strategies for route segments that carry unavoidably high risk. These “virtual surveys” can be updated quickly and cost effectively using remote sensing methods and mobile mapping.

If geospatial information about critical transportation assets is kept up-to-date and available in searchable databases, these same technologies can assist first responders in case of an attack by providing detailed routing and terrain information. Such information will improve the speed and quality of the response while at the same time improving safety and reducing casualties.


For rail security, one of the primary needs is to develop “intelligent railroad systems” that employ digital data communication, data, and on-board sensors for improving safety and security of the trains and their cargos.

Ultimately, intelligent railroad systems allow operators to respond to unexpected events virtually anywhere in their systems. Taken together these benefits provide broad incentives for rail operators to institute such improvements as the use of digital data link communications, positive train control, nationwide differential GPS, automatic equipment identification, electronically controlled pneumatic train brakes, and intelligent grade crossings.

Positive train control systems are digitally linked communication systems that provide safety benefits by preventing collisions, preventing over-speed accidents, and protecting roadway workers. They can enhance rail security by monitoring location and speed of all trains, and by monitoring the status of all rail switches. Such systems can make excellent use of the National Digital GPS (NDGPS) system that is currently operational throughout most of the United States.

These technologies, which provide continuous, realtime information, enhance security through prevention, detection, and notification of rail accidents and other incidents. They also assist in the recovery from incidents. Because the security of information provided by intelligent railroad systems is itself of great concern, systems to provide information security must be designed into them from the beginning.

Remotely sensed data provide an excellent, unbiased source of information for determining rail transportation vulnerabilities. When combined with intelligent railroad systems in a GIS framework, such data provide an additional margin of safety for the transport of hazardous materials.


Ports constitute a significant element in the nation’s transportation infrastructure, for they serve as primary transportation nodes for transferring cargo to and from ships to rail and highway transportation. Port security and the ability to respond quickly and efficiently to attacks can be increased substantially through the use of geospatial technologies.

Aerial and satellite imagery are particularly valuable for viewing and analyzing vulnerabilities within and around ports. A variety of geospatial tools is available for creating these. Pictometry, Inc., for example, employs a unique aerial system of oblique digital imagery acquired from many different angles. This technique enables the firm to explore a variety of scenarios to identify and test potential vulnerabilities of transportation routes into and out of the port (Figure 1). Note that in many situations, oblique imagery allows the camera to view under bridges and other structures to illuminate details that would be missed in most overhead imagery.

The system is also capable of undertaking threat and response analysis of potential attacks (Figure 2), helping port managers to identify the most important infrastructure on which to spend limited security budgets. Further, this tool, combined with other geospatial tools and risk models, can be used to support real-time decision making in case of attack. Figure 2 illustrates the ability of the system to allow modeling of a chemical plume released by an attack, using models of prevailing wind patterns. Note that in this case, the port’s command center and main entrance lie in the path of the chemical plume. In the case of an actual attack, imagery acquired in advance can be retrieved and merged with real-time local environmental data in a model to estimate the spread of potential chemical plumes across an area. Such information can reduce the loss of lives of responders and those directly affected by the attack, and aid in rapid recovery.

Meeting the Needs of the Security Mission

State and local agencies and officials are on the front line in the effort to meet terrorist threats. The following issues need to be addressed in the quest to develop adequate local transportation security:

Access to Imagery and Data Fusion

Remotely sensed data serve as decision-making tools for all levels of officials. There need to be clear policies for access to various types of geospatial information across and within political and geographical jurisdictional boundaries. First responders need access to critical information about pre-attack conditions of transportation links and the related infrastructure in order to establish an accurate baseline from which to work in providing succor to the injured and in clearing routes in and out of the affected areas. Such data would allow first responders to find street intersections and building foundations even when the surrounding areas are badly damaged or covered with debris as they were in the aftermath of the Sept. 11, 2001 attack.

Improvements in transportation security will require the fusion of many different kinds of data. Geographic information systems (GISs) generally serve as the integrative foundation and platform for fusing different forms of geospatial data with other forms of data, such as still and video imagery, street addresses, and structural types.

Data interoperability, Formatting, and Access Protocols for Multi-Agency Use

To reach the greatest effectiveness across institutional boundaries, data need to have sufficient commonality to allow sharing among different software platforms. At a minimum, geospatial data should conform to the standards of the Federal Geographic Data Committee (FGDC). Geospatial data and software should have additional characteristics in order to make them broadly useable, including multi-machine compatibility (desktop, laptop, handheld), commonality (of format, metadata, georeferencing) and connectivity.

Employing the Full Range of Remote Sensing Technology and Data Products

Many security needs can be met by existing technologies and by data products that have been developed for other purposes. Remote sensing methodologies exist to anticipate, plan for, and mitigate the effects of natural disasters. These methods include many that involve transportation in and out of the affected area.

Sources of Remotely Sensed Data

For U.S. transportation needs, numerous sources of remotely sensed data exist from both aircraft and space sensors. The choice of data source to use for transportation purposes depends on a variety of factors, including cost, ease of use, spectral characteristics, spatial coverage, and temporal characteristics. Potential aerial platforms range from single and twin engine fixed wing (propeller and jet), to helicopters and unpiloted air vehicles (UAVs) and even tethered balloons.

UAVs, although they are still very much under development, offer especially interesting possibilities for transportation security applications. The use of these systems in Afghanistan and Iraq to assist in peacekeeping, and in the U.S. Gulf Coast region following Hurricane Katrina will provide lessons for future applications of such systems. Further, the international community, especially Europe, is investing heavily in UAV R&D.

Awareness, Education, and Training

Outreach, education, and training have important roles in the effort to develop state, regional, and local capacities to secure and protect transportation infrastructure. One of the major barriers lies in the lack of understanding among responsible officials of how geospatial tools and data can assist transportation security. Agency of- ficials need to understand that remotely sensed images are multilayered information sources that can dramatically change the way in which officials can carry out the mandates of their agencies. Training for using geospatial information also needs to be extended to first responder teams in order to improve their efficiency in understanding and using image data.

Crafting a Research and Implementation Agenda

Developing a clearly articulated implementation agenda is an important first step in the process of improving the nation’s transportation security. Geospatial systems can enable the crafting and implementation of a new vision for homeland security, but the R&D community must continue to think and act creatively in order to make such a vision possible. NCRST-H created proposed research and implementation agendas for intermodal freight and for hazardous materials transport for consideration by policy makers and the research community (see Boxes H and I).


Remote sensing and other geospatial technologies provide many useful tools for improving and expanding U.S. transportation security. The introduction of such tools or their expanded use will also assist overall transportation safety. Nevertheless, geospatial technologies cannot provide the total solution. They must be integrated with other information and incorporated within appropriate institutional structures.

The research community needs to focus its efforts and funding on providing detailed geospatial information in useable forms that respond to the users’ specific needs. Therefore, researchers need to collaborate with the local communities that will need geospatial tools to help them identify transportation vulnerabilities and imminent threats and to respond quickly and efficiently in case of attack. First responders are critical to preliminary planning, and in case of attack, to minimizing loss of life and damage to transportation infrastructure.

When integrated with other geospatial data, remote sensing provides an important tool in preparing the nation to meet the terrorist challenge. It is especially useful for developing the necessary background maps and analyzing various attack scenarios to assist in preparing for attacks on vulnerable facilities, and for increasing the possibility that attacks can be deterred.

This article is adapted from Ray A. Williamson and Amelia Budge, “Preparing for the Unknown: Geospatial Technologies for Improving Security in Intermodal Freight and Hazardous Materials Transport,” National Consortium for Remote Sensing in Transportation-Hazards, Safety and Disaster Assessment, 2004. Many thanks to all those who contributed to this report.

Available at www.trans-dash.org/ and www.gwu.edu/~spi (reports). NCRST-H was funded by the Department of Transportation, Research and Special Programs Administration.

Sensors & Systems | Monitoring, Analyzing and Adapting to Global Change | Stay in tune with the transformation. Subscribe to the free weekly newsletter.