Repairs to a bridge in Essex, costing £12m and started three years ago, have failed to fix one of the major problems.
Work to stop water leaking from drains into the structure of Pitsea Flyover bridge began in 2004.
Essex County Council's highways department said engineers had worked from incorrect technical drawings.
Transport councilor, Norman Hume, said it will now cost more money and take months or even years to complete repairs to stop the leaks.
The original architects' drawings were given to the contractors, but as the work neared completion it was discovered the bridge drains were not built as designed.
Labour councilor, Keith Bobbin, who represents Basildon and Pitsea, said the project had wasted money. "If they'd done the job in the first place we probably wouldn't be in this situation today."
Mr Hume defended the work, which has included replacing street lights, crash barriers and improving the road surface of the A13 it carries.