Archaeological finds cost £17m
The removal of archaeological finds during road building in Northern Ireland has cost the taxpayer an extra £17 million.
When contractor Amey Lagan Roads began excavation work in November 2007, large but low value objects were discovered in three schemes in counties Down and Tyrone.
They included Bronze Age cooking sites dating back thousands of years as well as the contents of pits and ditches.
An Audit Office report into Roads Service's settling of claims said substantial work was required by the contractor's archaeologists to record the features.
"Given the inherent unforeseeable nature of the risk, it is unlikely that risk could ever be easily or adequately evaluated and priced," it said.
"Our general conclusion is that Roads Service acted reasonably in retaining the risk of unforeseeable archaeology."
The government business unit, part of the Department for Regional Development, and Amey Lagan Roads, a consortium, signed a contract worth £225 million to design, build, finance and operate 78 miles of motorway and main road.
It included the upgrade of a stretch of the A1 near Newry to dual carriageway, junction improvements at Hillsborough and Banbridge and the rebuilding of the road between Dungannon and Ballygawley to dual carriageway standard. That involved the removal of large areas of earth.
Under the contract the risk of extra expense to excavate archaeology uncovered was shared, with Roads Service carrying the risk that additional costs could be incurred by the contractor for unforeseeable finds.
The private firm was liable for all costs involving predictable recoveries of archaeology.
In conventional contracts the company shoulders the risk of discovery of all archaeology.
Initially this contract required the decision on unforeseeability (whether the contractor or Roads Service were liable) to be made before the removal of the archaeological features, but the amount of discoveries would have effectively prevented work throughout the site.
In response, Roads Service amended the contract to allow removal without determining whether the find was foreseeable, avoiding unnecessary delay and trying to reduce costs.
Afterwards the contractor argued that all finds were unforeseeable and were the government agency's responsibility, and in September 2010 submitted a claim for £33.7 million to cover the extra costs.
Roads Service offered £8.6 million. Following mediation a settlement of £17.2 million was reached.
The Audit Office added: "Lessons learned by Roads Service and the Northern Ireland Environment Agency have been used in more recent road schemes.
"Trial trenching has been carried out during the clearing of the site, mitigating the risk of similar issues arising during further work."
The watchdog said: "In our view, this will provide greater protection to public resources."