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PATH tunnels seen as fragile in bomb attack

(The following article by William K. Rashbaum and William Neuman was posted on the New York Times website on December 22.)

NEW YORK -- An analysis done for the Port Authority of New York and New Jersey says that the PATH train tunnels under the Hudson River are more vulnerable to a bomb attack than previously thought, and that a relatively small amount of high explosives could cause significant flooding of the rail system within hours.

The analysis, based on work by Lawrence Livermore National Laboratory and the Rensselaer Polytechnic Institute, revises some critical aspects of an assessment of the system’s vulnerability that was presented to the agency last spring. It makes clear that the tunnels — four tubes of varying design and sturdiness that stretch across the Hudson riverbed — are structurally more fragile than first thought.

A draft summary of the most recent analysis was given to The New York Times by a government official who was troubled by what the official felt was a lack of action in response to the analysis, which the official said the Port Authority got about three weeks ago. The official said the latest analysis indicates that it would take only six minutes for one of the PATH tubes to flood if a significant but not necessarily very large bomb were detonated.

Marc La Vorgna, a spokesman for the Port Authority, would not answer specific questions about the analysis, or with whom it had been shared.

“If we believed in any way that passengers were in danger, we’d close the system,” he said. “That would happen immediately.” He said the Port Authority police had substantially increased patrols and bag searches in the PATH system in recent weeks. In addition, the agency’s board voted on Dec. 14 to spend $180 million on PATH security improvements. He refused to say what had prompted the actions.

The vulnerability of the PATH tubes and other tunnels has long been a source of concern to security, transportation and government officials, as well as the public. It has given rise to various projections about their likelihood as a target and what ought to be done to safeguard them.

The fears have existed at least as far back as 1993, the year of the first terror attack on the World Trade Center. Various agencies, including New York City Transit and the Metropolitan Transportation Authority, over the years have been studying ways to improve the tunnels’ security and stalwartness.

Just last July, several people were arrested overseas in what authorities said was a plot to bomb the PATH system — which has a weekday ridership of 230,000. The arrests halted what officials said was a bid to set off backpack bombs in a PATH train car and flood the tunnels. Some published reports said maps and other material relating to the PATH tunnels had been found on the computer of one of those arrested.

That investigation began a year before the arrests, about the same time that an analysis of the vulnerability of the transit system’s underwater train tubes was jointly commissioned by the Port Authority and the Metropolitan Transportation Authority, which oversees the operation of the city’s subways. It is unclear, however, whether the investigation prompted the analysis.

A 19-page summary of the analysis details some of the measures the Port Authority has been planning to put in place to better secure the PATH system: laying concrete blankets atop the tubes to plug holes caused by a blast, strengthening portions of the tubes and installing floodgates to prevent the system from being overwhelmed.

The official who gave a copy of the report to The Times said the Port Authority, whose executive director and board members are appointed by the governors of New York and New Jersey, had informed neither state executive of the most recent results. Neither has it yet shared the new findings with the United States Department of Homeland Security, Mayor Michael R. Bloomberg, the New York Police Department or other law enforcement agencies, the official said.

The official disputed the Port Authority’s contention that it had increased patrols and bag searches.

Aides speaking for Gov. Jon S. Corzine of New Jersey and Gov. George E. Pataki of New York would not comment on whether the two leaders had been apprised of the latest analysis, but they insisted that the governors are both fully and regularly briefed on the security of the region’s mass transportation system.

A spokesman for Mr. Bloomberg would not comment on the analysis. But a senior Police Department official acknowledged that the police had not been informed of the newer findings. Yesterday afternoon, Russ Knocke, a spokesman for the Department of Homeland Security in Washington, said he could not determine whether anyone at the agency had been notified.

Speaking generally, Mr. La Vorgna of the Port Authority said the agency was “constantly undergoing threat assessment,” and that the analysis was regularly shared with its federal, state and city partners.

Since 9/11, government and security officials have emphasized that there is no way to fully protect every possible target. But in New York, officials have regularly sought to reassure the public that serious steps are being taken to address major vulnerabilities in the area’s array of tunnels, bridges and rail systems.

The analysis appears to be the most detailed and sophisticated government review of the train tubes’ vulnerability. Initial findings were shared last May with some members of the agency, but were not made public, and further tests were ordered. More tests are being done in an effort to come up with the best way to strengthen the tunnels.

The Hudson River tubes of the PATH system, which suffered serious damage in the 2001 terror attack, are more vulnerable than most other tunnels that pass under the city’s waterways because they lie in the soft riverbed, unlike other tunnels that are bored through the underlying bedrock. Silt over years has built up atop the tubes, which were laid roughly 90 years ago, but they are not in bedrock.

Several city subway tunnels beneath the East River are in many ways similar to the four PATH tunnels — essentially cast-iron tubes that run along the riverbed. An official at the Metropolitan Transportation Authority said that agency is working on an analysis of its tubes.

The PATH analysis, which is characterized as preliminary and continuing, examines the three different types of PATH tubes under the Hudson. Roughly three-quarters of the tubes’ total length is made of unlined cast iron, with the balance made from concrete-lined cast iron or brick. Many of the details of the analysis — including the size of the bombs under discussion, their placement and the exact nature of the vulnerability — are being withheld by The Times.

The worst case included in the analysis suggests that a bomb that could be easily carried aboard a train could punch a 50-square-foot hole in one side of a tube, possibly breaching both sides of the tunnel. Under that situation, 1.2 million gallons of water a minute could pour into the tunnel, flooding parts of the system in a matter of hours.

That is a much more dire view than an earlier draft of the analysis — completed last May — contemplated.

PATH trains run in sets of seven cars, each with a capacity of 130, so that there could potentially be about 900 people on a crowded train. New cars on order would allow 10-car trains that could carry more people.

The analysis — presented in November by a senior member of the Port Authority’s engineering department to a small group of the agency’s senior managers, says that the new results are based on a combination of tests on the cast iron from the tunnels and computer modeling. It recommends seeking an additional $3.8 million to supplement the $4.5 million already authorized for the continuing analysis.

Additional computer models, it said, were also being run to develop more specific results. The Livermore laboratory, a government-financed institution that evaluates security threats, has also done blast analysis for the Bay Area Rapid Transit system in the San Francisco Bay area.

The strategy to minimize the impact of explosions in the tunnels has been organized into a three-part program, according to the report: Laying down the material to cover the tubes, known as Geotextile Concrete Mats; installing floodgates on the tunnels to minimize flooding, protect other parts of the system and allow repair after a blast; and strengthening critical portions of the tubes.

Simulations show how, “in the event of a tunnel breach the mat would be pulled into and clog the opening to at least reduce the rate of inflow of soil and water into the tunnel,” the summary said.

The summary recommended that Port Authority officials seek authorization for an additional $71 million to build and install floodgates at the World Trade Center and Exchange Place stops at the agency’s December board meeting, which occurred Dec. 14. Mr. La Vorgna would not say what measures were covered by the $180 million the agency voted to spend on PATH security improvements or whether that sum included the $71 million.

Friday, December 22, 2006

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