Underwater complications have sent the Wil-kinson Eyre-designed Millennium bridge in Gateshead £1 million over budget.
The footbridge, which lifts to allow the passage of ships along the Tyne, will now cost the scheme sponsors - the Millennium Commission and Gateshead Council - around £19 million.
The extra costs stem from the need to mark off a 30m-wide deep channel to allow ships as large as 4000 tonnes to pass under the raised bridge, and difficulties in pile-driving beneath the Tyne. New rules also mean that silt which has been dredged up must be deposited in land-fill, not at sea, as was first planned. The extra costs are likely to be met by Gateshead council.
But the engineers and architects are at odds with the harbour-master over the need to design the channel for heavy traffic
'There really aren't many boats passing up the Tyne now,' said John Johnson, director of engineering at Gateshead Council.
The architects said that the principal reason for having the opening was to allow for the passage of the tall ships yacht race which starts annually from Newcastle.
'The harbour-master has been difficult to please, but he is in a very strong position. This shipping-protection system has been included in the target cost, but everyone is very unhappy with it. It doesn't look very good,' said Jim Eyre, partner at Wilkinson Eyre Architects.
The channel consists of two rows of piles topped with grey-painted steel which rise more than 5m out of the river at low tide and are linked by partially submerged floating booms. They will constrain ships to the central, deeper part of the river.
Eyre stressed that the project is still due for completion in April or May this year. He also praised the partnership arrangement between the architect, Gifford & Partners, the design engineer, Gateshead Council and Harbour & General, the main contractor for the works. He said that its transparency means that cost increases are likely to arise during the course of the project, rather than 'the contractor storing them up and producing a whopping bill at the end.'