NZTA Otago senior network manager John Jarvis said it cost about $200,000 a year to maintain the 127-year-old Clutha River bridge on State Highway 8.
He said the most recent repairs were carried out at the end of last year, and there were no immediate plans to replace the bridge.
The agency had not included replacing the bridge in its three-year programme, and it was unlikely to be included in the next programme.
''We've managed to arrest deterioration with ongoing maintenance ... It's in better nick now then it was several years ago.''
On average, 1530 vehicles use the bridge each day.
Mr Jarvis said annual maintenance costs had remained around $200,000 over the past four years.
In 2010, traffic lights costing $180,000 were installed to make driving on to the bridge safer and to reduce speeds, which also reduced damage and maintenance.
The scaffolding along the sides of the bridge was introduced in 2008, with more put in place the following year.
''It's in better condition than it looks.''
The bridge, which has a single-lane wooden deck with wrought-iron trusses, was opened on March 3, 1887.
In contrast, the Kawarau Falls bridge on State Highway 6 at Frankton, costs $50,000 to maintain each year, and the average daily traffic count is 6500 vehicles per day.
A design for a replacement Kawarau Falls bridge is in the design phase, and had not yet secured funding, Mr Jarvis said.
In November Remarkables Park Ltd and the Frankton Community Association withdrew appeals against the notice of requirement to alter the existing designation to enable construction, operation and maintenance of a new two-lane bridge on State Highway 6 across the Kawarau River in Frankton.
The design and construction of the new bridge were included in the agency's 10-year state highway plan.
The construction programme must first go to the Otago Regional Transport Committee for inclusion in the 2015-18 regional land transport programme, then through the agency's national prioritisation process for funding consideration.
Last year the Clydevale bridge was strengthened to class 1 standard, restoring it to full heavy-vehicle capacity.
The Clydevale bridge spans the Clutha River about 22km northwest of Balclutha. It is a key transport route, as some oversized loads cannot be taken over the Balclutha bridge.
In September, the bridge reopened after two months of strengthening work and lengthy detours for motorists.
The upgrade was completed slightly ahead of schedule and came in under its $418,052 budget at $395,000.
The second stage of repairs to the Clydevale bridge will be carried out this month. The contract to repair the bridge piles was awarded to Fulton Hogan Ltd for $374,847.
