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Tuesday, December 30, 1997 Published at 03:25 GMT

World: Europe

Leaning tower of Pisa to get braces
image: [ Two steel braces will shore up the tower during restoration work ]
Two steel braces will shore up the tower during restoration work

Conservationists plan to prop up the Leaning Tower of Pisa, in Italy, with two steel "braces."

These will steady the fragile structure during key preservation work next year.

The two plastic-coated steel cables will be temporarily attached to the second tier of the white marble bell tower at a height of 22 m.

Michele Jamiolkowski, president of the international commission of experts restoring the tower, said the steel supports would "give us greater peace of mind while work is being carried out.

"We don't want to be scared to death again," he said.

[ image: The lean used to increase by an average of 1.2mm a year]
The lean used to increase by an average of 1.2mm a year
In September 1995, the medieval monument suddenly lurched 2.5mm in one night - about 10% of the lean that the commission had corrected since 1990.

Following the scare, 830 tonnes of lead blocks were positioned to counterbalance the tower.

The tower, one of Italy's most famous monuments and a magnet for tourists mesmerised by its alarming tilt, has been closed since 1990.

Tourists were stopped from climbing to the top in an attempt to save the tower by correcting the lean, which used to increase by an average of 1.2mm a year.

It stopped leaning in 1993 after the first stages of the restoration project. The commission aims to correct the tilt by half a degree.

Michele Jamiolkowski said: "That may not sound much but it's enough to guarantee us peace of mind for hundreds of years."

The tower was built on shifting subsoil between 1174 and 1350 as a belfry for the nearby cathedral, and is said to have been used by 16th century astronomer and physicist Galileo for experiments in working out the laws of gravity.

It developed its distinctive lean during the 12th century.

The steel braces are designed to shore up the 14,000-tonne tower during an operation to sink 10 anchoring cables that will eventually stabilise it.

They will be attached to special structures on the north side of the surrounding square.

Counterweights will be fixed to the end of the anchoring cables to keep them taut.

If the tower should suddenly show signs of shifting, the weights could be increased to 100 tonnes to keep it standing.

The experts plan to construct a huge ring of cement underground around the underground foundations, with the 10 steel cables linking one side of the ring to firm layers of earth some 5m below.

Each cable will withstand some 100 tonnes of pressure. Engineers say that will pull the 58m tower back two centimetres from its lean and stabilise its tilt at about five metres off the perpendicular.

Preliminary excavation work will begin next year.

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