Terrorist attacks have shifted from air to rail, study suggests

In his study -- "Has Successful Terror Gone to Ground?" -- Professor Arnold Barnett of the Massachusetts Institute of Technology Sloan School of Management writes that strong, statistically significant evidence points to a growing focus of terrorist attacks against ground mass transit. By far, the deadliest attacks against air and rail in the decade 2002−2011 were against subway and commuter rail systems, taking 200 lives apiece.

In a previous analysis for the period 1968 to September 10, 2001, the author concluded that air travel within the United States entailed a greater risk of a terrorist attack than "virtually any other activity." The new Barnett paper with a different conclusion recently appeared in the online version of Risk Analysis, a publication of the Society for Risk Analysis.

The author notes that the statistical risk posed to travelers by criminal/terrorist acts against air and rail are minuscule, but he argues that successful acts of terror have ramifications far beyond their immediate consequences. For example, many observers believe that the Madrid commuter-train bombings in 2004 changed the outcome of the Spanish national election shortly thereafter. Barnett contends that "if terrorists give weight to demonstrated success," then the vulnerabilities illustrated by recent rail bombings from Great Britain to Sri Lanka could be precursors to further attacks. And because there is scant evidence that attacks on rail systems can be thwarted while in progress, the greater terrorist interest in railroads "heightens the urgency" of intercepting terror plots in advance. Barnett concludes by noting that a planned 2009 New York subway attack was thwarted by good intelligence work, not by security measures at Times Square or Grand Central Station.

In his analysis, the author excluded the 2,765 ground deaths suffered during the September 11, 2001, terrorist attack against the United States because his analysis focused on risks to air and rail passengers. The 9/11 casualties would have overwhelmingly dominated the analysis had they been included, raising the danger that the understandable preoccupation with the 9/11 calamity would "obscure less extreme patterns related to acts of terror." Identifying such patterns was the main point of the article, the author notes.