The Leaning Tower of Pisa in Tuscany attracts more than 5-million visitors each year – and is admired for its strength to shine in the face of adversity. After years of extensive consolidation work on the tower, it has lost 4cm of its tilt, and may in fact be leaning in reverse. In January 1990 the tower was closed over safety concerns when its tilt reached 4.5 metres from a vertical position.
The corrective work, carried out between 1993 and 2001, was done to reverse the slump and keep the tower from falling over.
The Leaning Tower of Pisa has straightened by 4cm.
Nunziante Squeglia, a geotechnics professor at the University of Pisa, said that since the restorative work began, the tower is leaning about half a degree less. The data from the tower is constantly reviewed by a committee that gets together every three months.
While the reduction of the tilt is not expected to last forever, it has caused significant change and the committee has reason to believe it can withstand another 200 years.
The tower is located behind Pisa’s cathedral and the original building was constructed in 1172. Due to the porous clay soil beneath its foundation, it began to tilt almost immediately. After three floors were finished, construction had to be stopped and did not continue until 90 years later. When the construction began again, workers tried to build extra floors to counter the lean. The construction was stopped again and only finished in 1372.
The operation to save the tower from toppling over is incredibly complex but the concept is easy to understand. Since the tower leans south, part of the soil under the northern side was removed, creating space so the weight of the tower shifts, closing the cavities and straightening the building in the process.
The last measurement shows that the building is in good health and it has straightened by 4cm.
Pictures: Pixabay
