WITH a life span of 100 years, Fiji Roads Authority will need to replace 10 bridges each year out of 1000 bridges around the country to keep up with their deterioration rate.
But FRA capital works manager Ian Hunter said if bridges only lasted 50 years on average, they would then need to replace 20 bridges per year.
Mr Hunter said at $3million to $5m each, it represented a substantial increase in annual replacement cost compared with the relatively modest extra cost of building them to a higher standard in the first place.
He said with all the bridges built in Fiji prior to those under construction today, there were concerns about deterioration of the concrete and reinforcing steel, and the effect that they would have on the useful life of the structures.
He added the new standards adopted by the FRA should ensure useful lives of 100 years or more rather than the 35 to 50 years expected of older bridges.
China Railway First Group project engineer Jeff Peng said bridges constructed in the past did not last very long because they were not made of anti-corrosive concrete and steel.
He said the difference between earlier bridges and the new ones being constructed along the Dreketi-Nabouwalu highway was the use of common materials.
He said this was one of the reasons former bridge structures did not survive long under pressure.
"For instance, the Waibunabuna Bridge we are currently constructing in Bua will have 13 tonnes of reinforcements for its foundations only," Mr Peng said.
"Along with this is the usage of 80 cubic metres of anti-corrosive concrete for the foundations too."
Mr Peng said pile-driving works had begun for nine bridges out of the 14 scheduled for the project.
"Former bridges were intended to have a life-span of 30 years but the new ones that we are intending for this project will last 100 years."
In a statement on Tuesday, CRFG spokesman Donald Singh said OPUS International Consultancy Limited had been engaged to carry out bridge design consultancy to produce the best bridge designs.