Superstorm Sandy caused more damage than thought to Hudson and East river rail tunnels

Repairs on Superstorm Sandy-damaged rail tunnels used by trains linking New York with the whole Northeast Corridor could cause a service nightmare.

Longer closures to do the work would cut service on Amtrak from 24 trains an hour to six, railroad officials said Thursday.

"The idea of going from 24 trains an hour to six trains an hour is really something that no one wants to see," Amtrak spokesman Craig Schulz said, adding that it would create a ripple effect on the Northeast Corridor from Boston to Washington.

Weekend crews have been working on two tunnels — under the Hudson River and the East River — but engineers have found that damage from flooding in the 2012 storm was more extensive than first thought, requiring the extended closures.

That's bad news not only for Amtrak passengers but also those on the Long Island Rail Road and New Jersey Transit using the tunnels. About 400,000 passengers ride trains through the tunnels each weekday.

Amtrak made the announcement as it released an engineering report detailing the damage to structural components from saltwater that inundated the tunnels during the storm, which was spawned in October 2012 when Hurricane Sandy merged with two other weather systems. While the report found no evidence that the tunnels were unsafe, it concluded that the saltwater has caused significant damage to the track, signal, electrical and mechanical systems.

The Amtrak spokesman said it would take a year to do the prep work for closing an East River tunnel, then another year to do the work. For the major repairs, one tube of the two Hudson River tunnels would have to be shut down for a year.

The report did not offer a firm timetable for the repairs.

It underscores the need for a new tunnel under the Hudson River known as the Gateway Project, which includes plans for two new tunnels to Manhattan's Penn Station. Amtrak proposed the Gateway Project in 2011, saying it would cost billions of dollars.

The railroad's preferred option for the Hudson tunnel would be to build the Gateway tunnel before closing the Hudson tunnel, Schulz said.

The report "puts an exclamation point" on the need to build a new tunnel, he said. "That is absolutely our best-case scenario."

Such a plan would allow trains to enter a new tunnel with two tubes while the existing tube is down for the necessary work, Schulz said.

Officials said they expected insurance to cover the estimated $689 million repair costs.

Only two of the four tubes of the East River tunnel, which runs from Penn Station to Queens, were damaged in the storm.

The Hudson River tunnel's two tubes link North Bergen, New Jersey, with 10th Avenue in Manhattan.