Twin Towers' stairs on the move

A staircase at the World Trade Centre that proved a lifeline for countless September 11 escapers and survived the devastation will be moved from the site his weekend.

The 37 steps that once connected the outdoor plaza outside the twin towers to the street below remain the only above-ground remnant of the complex and will eventually be part of a permanent monument.

Preservationists and survivors of the 2001 terrorist attack began campaigning years ago to leave the staircase as it stood, while developers refined plans for office towers, a transit hub and memorial on the 16-acre site.

The staircase, which weighs 175 tons, is in the middle of the site of a 1,278-foot skyscraper, one of five being built to replace the destroyed towers.

In 2006, state officials announced they would demolish all but one or two slabs of the staircase to make way for the new tower, undeterred by a preservation group that named the steps one of the US's most endangered historic places.

The site's owners, the Port Authority of New York and New Jersey, said the piece could not be moved because it is too tall for traffic lights and overhead poles and possibly too heavy for bridges.

"You would have to have started moving light poles" to move the staircase intact, said Steve Plate, the agency's director of priority capital programs who oversees the trade centre site's redevelopment.

A compromise was reached last year to separate the stairs from their concrete base and install them at the memorial.

"The goal was always to preserve enough of this staircase to really communicate its power," said Joe Daniels, president of the foundation building the memorial. "We can reduce the whole size of this thing but still capture the essence of the stairs."

This weekend, a 500-ton crane will lift the piece onto a flatbed lorry and move it to the west side of the site.

By summer the stairs will move again, this time a crane will lift them 70 feet (in the air) and across the site to the memorial.