EXPERTS at AWG are trying to discover what caused part of a new £25 million road improvement scheme in Scotland to collapse last week, causing traffic chaos.
The site team stopped work on building a new junction on the A80 at Auchenkilns between Glasgow and Stirling when part of the job was hit by subsidence.
An AWG spokeswoman said: 'We experienced some unexpected settlement on a temporary diversion area on the site.
'The site team was alarmed enough to take the step of closing that part of the job.
'It's a very small area of the site, affecting a slip road coming onto the main road.
'We are now working round the clock with the client, designer and consultants to find out exactly what caused it.'
The closure resulted in major traffic disruption on the busy route and AWG has been forced to rebuild part of the old road it had ripped up to use as a temporary route.
The spokeswoman said: 'We successfully reopened a two-lane northbound carriageway last Thursday and pulled out all the stops to get that done to minimise disruption.'
Subsidence problems on the job are believed to have been caused by poor ground con-ditions, typified by up to 7 m of 'boggish peat' in some places.
Embankments along the route have been reinforced with 12 m deep piles.
Work started on the junction improvement in January and the design and build contract is due for completion by summer 2005.
The job involves construction of a junction, four slip roads and a bridge to replace the existing roundabout.
The AWG spokeswoman said: 'Work is carrying on as normal on other parts of the site while the investigations continue on the small affected area.
'The completion date for the job shouldn't be hit.'
A spokesman for the client, the Scottish Executive, said: 'The ground is marshy, which has created problems. AWG is doing all it can to control the situation.'