Relief for the Coromandel's traffic woes is gradually coming as the skeleton of the Kopu Bridge replacement begins to climb above the Waihou River.

Holidaymakers and Coromandel residents still have to endure two more summers of long traffic queues before the $47 million project near Thames is completed.

But the construction project is already bringing some economic benefit to the region, with 40 people directly employed on-site and another 100 involved downstream, in supply and support services.

New Zealand Transport Agency regional director Harry Wilson said that while the project would have long-term benefits for the region, the agency was aiming to maximise the benefits of the construction phase.

Almost all of the resources were New Zealand-sourced, and where possible, from the Coromandel region.

Nearly 185,000 tonnes of fill has been taken from Leach's Quarry near Kopu to create a firm foundation for the bridges' steel-cored piles, which are driven 36 metres into the riverbed.

Mr Wilson said the construction was time-consuming because of the soft, swampy ground in which the new structures were being placed, but the project was still on track for the original completion date in July 2012.

The new 580 metre, two-lane, steel bridge should ease the notorious bottleneck which builds on either side of the one-lane bridge at peak times.

The narrow, traffic-light controlled bridge is the key connection between Auckland and the peninsula, and drivers experience delays of up to three hours during the holiday season.

The replacement bridge will be more than three times the width of the original bridge. The older structure, which opened in 1928, will be upgraded from its shaky timber-and-wire state.

The project was brought forward under a $500 million jobs and growth plan announced by the Government last year.

It will include 2.5 kilometres of approach roads and a four-leg roundabout to replace the difficult intersection of State Highways 25 and 26.