Bridge set to reopen ahead of schedule

Grafton Bridge remains open to pedestrians. Photo / Brett Phibbs

Auckland City's pioneering Grafton Bridge is expected to reopen in October - more than two months ahead of schedule - after being bolstered with carbon fibre in a $6.9 million strengthening project.

Council project manager Graham Long said yesterday that the strengthening work, which has included injecting epoxy resin into 805 metres of cracks in the 99-year-old structure's concrete beams and columns, was headed for completion in September.

That would allow the two-lane bridge to reopen in October, at the same time as the rest of the council's $43 million Central Connector busway between Britomart and Newmarket, which Mayor John Banks sees as the most critical public transport project undertaken by the city.

But the council has yet to decide under what conditions the bridge will reopen, and whether to persevere with a ban on its use by traffic other than buses, emergency vehicles, motorcycles, bicycles and pedestrians from 7am until 7pm each working day.

Mr Banks said the council was still consulting interested parties including Grafton retailers before its transport committee would be ready in September to confirm or modify the original plan, developed before political change at the last local body polls.

Mr Banks said he had his own views, which he was not ready to reveal, although he believed an effective public education campaign had minimised disruption to traffic since the bridge closed in October last year.

Whatever is decided, Mr Banks disclosed that he was working with an unidentified charity to hold a fund-raising dinner on the bridge before it opens.

Lead contractor Brian Perry Civil and engineers Beca have been under strict instructions not to modify the look of the bridge, given its category A heritage status. Mr Long said the strengthening would increase its maximum load rating from seven-tonne to 44-tonne vehicles.

It would also gird the bridge to withstand an earthquake of a magnitude unlikely to occur on average more than once in 1000 years.

Most of the work has been unseen by pedestrians, who have been allowed to keep crossing the bridge as a crew of up to 70 workers toiled beneath them.

The underside of the 284m structure's central arch - at 98m the world's largest ferro-cement section when it opened in 1910 - has been enclosed by a deck of scaffolding which accounted for about $1.5 million of the project's budget and protects motorway traffic passing 43m below.

BRIDGING FINANCE

Construction cost in 1908-1910: About £40,000 (equivalent to $5.9 million today, according to the Reserve Bank's inflation calculator).
Structural strengthening project 2008-2009: $6.9 million.
Length: 284m.
Height: 43m above Grafton Gully.