The Leaning Tower of Pisa is in excellent health, the local heritage protection agency said on Wednesday.
The latest check on the historic landmark come 21 years after an adjustment to make it more upright in 2001. “Considering it is an 850-year-old patient with a tilt of around five metres and a subsidence of over three metres, the state of health of the Leaning Tower of Pisa is excellent,” said Opera Primaziale Pisana.
“As (then project leader) Michele Jamiolkowski stressed,” said Pierfrancesco Pacini, the president of the Primaziale, “the Tower’s stabilisation was a full blown and difficult challenge for geotechnical engineering. [This was] due to the fact the interventions at the foundations could have been dangerous and so the use of conventional technologies like cement injections or sub-foundation work bore an unacceptable risk”.
The monument is stable and has slowly lost a tiny bit of its trademark tilt, a group of researchers monitoring the Tuscan monument said recently.
A little less tilt
The tower lost a reported 4cm of its tilt in the past 20 years. Its health is better than forecast by an international committee coordinated by Jamiolkowski between 1993 and 2001.
Nunziante Squeglia is a professor of geotechnics at the University of Pisa who cooperates with the monitoring group. They said the tilt has decreased thanks to stabilisation work, along with “oscillations now varying at the average of 1/2 millimeter a year, although what counts the most is the stability of the bell tower, which is better than expected”.
The non-profit Opera della Primaziale Pisana funds the group’s activities. These monitoring the tower and improving the quality of conservation measures, as well as promoting research on the monument.
Tower may one day straighten up
At least one Italian official thinks the tower will one day straighten up, thanks to modern engineering. Giuseppe Bentivoglio, technical director of the monument, said the 56-meter bell tower’s lean towards the south is shrinking thanks to an 11-year restoration project completed in 2001.
The free-standing cathedral tower began tilting during construction, in the 12th century. It was due to an inadequate foundation on ground that was too soft on one side. Construction on the tower began in 1174. However, it was 1350 before completion when its tilt was already about half what it is today.
The tower was saved from toppling in a decade-long engineering project in the 1990s, reopening to the public in December 2001. It included steel girdles, lead weights, and a lot of digging. It cost 53-billion-lire, and straightened the tower by 40cm, moving it back to its position in the 19th century.
Before the efforts to reverse the lean, the tower was adding an average 1mm a year to its 4.5-metre lean. In 2005, a check-up on the tower’s health pronounced it safe for the next three hundred years.