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Nottingham Castle

ACCESS

HIGH on top of the cliff face on which Nottingham Castle sits, Central High Rise foreman Ian Townsend checks his harness and anchor points meticulously before abseiling casually over the edge of a 30 m drop.

After 12 years in the trade, it is second nature.

There are three steeplejacks working on the castle at the moment as part of a four-year contract worth £250,000. In 1998 a corner terrace viewing area outside the castle building collapsed, taking with it 30 tonnes of rock and alerting the local council to the erosion problems riddling the 40 m, soft sandstone cliff. Luckily, the landslide happened on Christmas Day and no one was injured, but the authorities realised that the cliff needed maintenance.

Central spends a total of 12 weeks a year on the site, clearing vegetation to prevent root damage, removing loose rock and pinning back other areas.The contractor also discovered that much of the slab failure was caused by undercutting.

Narrow gullies were eroding faster than other areas, leaving large, partially unsupported sections of rock suspended.To decelerate this process, workers are applying a sacrificial coating of sand, cement and styrene butadiene rubber to the gullies, which will erode instead of the rock itself.

The 17th-century building often disappoints tourists, who come expecting the full Robin Hood experience. But one positive consequence of the landslide was that it exposed a section of Medieval wall that visitors will be able to see when Central completes works on a viewing platform.

The scale and difficulty of access to the cliff face makes it a challenge to map.

'If you photograph one part from the top you can't tell the same part from the ground, ' explains Mr Turney.'It's a bit like photographing the Sahara desert - each time you change aspects it looks completely different.'

Mr Turney made an illustration of the cliff face and plotted co-ordinates on it using the natural boundaries of vertical gullies and horizontal strata layers, marking on where work needed doing.

'It's better than a grid reference, ' he says, 'because you can't look for invisible lines on a site, but you can count three gullies along.'