Prof. who helped save Leaning Tower of Pisa returns to Italy to celebrate 20-year milestone

by Colin Smith

A researcher from Imperial College London, his family, and a BBC film crew travelled to Italy last month to commemorate a project that prevented the Leaning Tower of Pisa from collapsing.

Emeritus Professor John Burland and his family visited Pisa with a film crew from BBC One’s The One Show to see the city’s most famous landmark. Twenty years ago, Professor Burland, from Imperial’s Department of Civil and Environmental Engineering, took part in a major international effort to rescue the 800-year old tower, which was in danger of complete collapse. The campaign was one of many projects Professor Burland worked on in his 50-year career and some of his family had never seen the tower before.

The One Show crew took Professor Burland back to the tower in April this year to talk about the engineering processes behind the project as part of show’s programme to mark the twentieth anniversary of the stabilisation project. The visit also enabled The One Show to highlight the wealth of world-leading engineering expertise in the UK.

Professor Burland says: “Working on a World Heritage site with a disparate group of highly intelligent professionals from all different backgrounds was a very rewarding and challenging process - one that I will never forget. When I first started the project 20 years ago the tower was in a sorry state. It was close to collapse and covered in centuries of grime. Coming back to Pisa all these years later, it is amazing to see the tower restored to its former glory. It was a great moment when I showed my family around the tower, which is one of the proudest achievements in my career.”

Scroll through the slideshow (below) to see Professor Burland’s visit to Pisa with The One Show and his family.

In March 1990, Professor Burland was asked to be part of a 14 member committee charged with stabilising the tower, which began to develop its characteristic lean after construction progressed to the second floor in 1178. The professor of soil mechanics worked for 11 years on the project, which saw 38 cubic metres of soil removed from underneath the raised end of the tower to slightly straighten it by 45 centimetres, returning the tower to a position previously seen in 1838.

The committee discovered that extracting the soil corrected some of the tilt, but it did not stop the tower from leaning more each year. After years of further research they discovered that the south side of the water table was higher than on the north side and in the winter when it poured with rain, the water table rose, lifting the tower each year in increments. The team rectified the problem by installing drains to control the water table beneath the north side.

In May 2008 the engineers announced that that tower had been stabilised and that they had stopped the building from moving for the first time in its history. In April 2011, the scaffolding came down to reveal gleaming stonework that had been restored to its original glory.

Watch the BBC interview, which starts approximately five minutes into the show, and see Professor Burland explain how the tower was stabilised, please click this link (available until Friday 13 May 2011).

Professor Burland has also been interviewed for the next edition of the Imperial College Podcast, , which goes online next Wednesday 18 May 2011. In this interview, Professor Burland chats about the engineering challenges that he faced during project and why, if he was sent to Mars, he would take Galileo - the famous physicist, mathematician, astronomer and philosopher - with him.