Booming demand for soil stabilisation has left specialist contractors short of the skills needed to cope with extreme ground and weather conditions, according to some geotechnical engineers.
Fears have been raised over the level of expertise in the industry after problems surfaced on the A10.
'Some companies have been in the business for more than 10 years, and they know what they're doing, ' said soil stabilisation consultant Chris Holt. 'But three or four years ago some 'tractor and plough' companies invested in the new generation rotary mixers, thinking it was an easy way to make money. It isn't, especially if the ground is very dry or very wet.'
Highways Agency senior geotechnical adviser Alex Kidd said: 'Lime stabilisation only works over a fairly narrow spectrum of moisture content, and it's easy to get it wrong. Good site control is vital.'