Though the restoration of the Leaning Tower of Pisa ended in 2001, it wasn’t until recently that the building was officially recognized as being stabilized, and the details of its mystery were revealed in a 1,000 page step-by-step publication The Tower Restored by the Committee for the Safeguard of the Leaning Tower.
The committee, commissioned with a $39 million budget by Italian Prime Minister Giulio Andreotti in 1990, consisted of structural engineers, art historians and architects and geotechnical engineers. Getting anything done with the combination of such differing disciplines, in addition to the complicated political sectors involved in the maintenance of the leaning tower, was difficult and time consuming.
Add to that, the fact that the committee was not permitted to disclose their processes, the public became quickly and passionately disgruntled about what they assumed was shady business and no real progress on their precious tower.
Finally, with this written account is a long overdue explanation of what was going down all those years from 1990 to 2001.
The eventual discovery of the cause of the lean, and the plan to stop it from falling even more, was the work of John Burland, the 72-year-old emeritus professor of soil engineering at Imperial College London, who also can be credited with the prevention of the collapse of Big Ben in 1990 during tube construction.
After a number of missteps by the committee over the years, including one attempt that caused the tower to fall even more, Burland determined that the tower was sitting upon a fluctuating water table in addition to already soft silt. He proposed soil extraction as the solution.
The team drilled into the soil on the south side of the tower, in opposition to its northernly topple, removing 70 tons of soil in the end. This caused gravity to shift the giant cylinder back toward its 19th century inclination. They also introduced a drainage system that would level the water table below the tower’s base, preventing further leaning from occurring again.
“We could have removed more, but our aim was to make the tower safe with as little intervention as possible,” Burland told the UK Telegraph.
And as long as it’s safe, who would want the Leaning Tower of Pisa to lose its charming slant anyway?
Photo by saturday_flowers via Flickr.