Time's up for tilting Big Ben

Click here to join natural wonders cool mail Time's up for tilting Big Ben By DAILY MAIL REPORTER Last updated at 5:50 PM on 10th October 2011 Iconic: Big Ben's tilt can now be seen by the naked eye Fears over the long-term stability of Big Ben have been raised because it is beginning to tilt to one side. The top of the clock tower is leaning one-and-a-half feet off a level position, according to surveyors, and getting worse each year. The tower in Westminster, which houses the giant bell known as Big Ben, is sinking into the banks of the Thames, partly as a result of decades of underground excavation. Subterranean works beneath the tower include the Jubilee line station, an underground car park and sewers. Its lurch of 0.26 degrees is said to be visible to the naked eye – and if it goes uncorrected could cause the tower to crash. However at current rates, it would take 4,000 years before the tower is as slanted as the Leaning Tower of Pisa which leans by four degrees and is around 12ft off the vertical. John Burland, emeritus professor at Imperial College London, said: ‘I’ve heard tourists saying “I don’t think it is quite vertical†and they are right. If it started greater acceleration we would have to look at doing something, but I don’t think we need to do anything for a few years yet.’ If Big Ben were to fall it would crash into MPs' offices over the road in Portcullis House. Currently, the clock tower is sinking more quickly on the north side of the 315ft-tall building. Clocking on: Workers checking and repairing the face of one of the world's most famous landmarks A just published 2009 survey for London Underground and the Parliamentary Estates Department found that the rate of movement has accelerated in recent years. Engineers cannot explain why the tower's clock face moved up to an eighth of an inch (3.3mm) away from the vertical between November 2002 and August 2003. Since 2003, monitoring instruments show the tilt has increased 0.04in (0.9mm) a year, compared to the long-term average rate of just 0.025in (0.65mm) a year. The report, obtained by the Sunday Telegraph, revealed that the tower  was now leaning towards the north-west at an angle of 0.26 degrees, meaning the top of the tower is 1ft 5in (435mm) from vertical.  The Leaning Tower of Pisa leans by around four degrees. Big Ben's movement has caused cracks in the walls of other parts of the House of Commons, including corridors where ministers and shadow ministers have their offices.