Coromandel gateway taking shape

Cranes lifting a steel truss onto the far side of the bridge.Photo / Christine Cornege.

The new link with the Coromandel Peninsula is taking shape with the erection of horizontal beams on piers for the $47 million replacement Kopu Bridge.

Fair weather yesterday enabled the last of an initial batch of four beams to be lifted into place across two piers in the middle of the Waihou River to allow construction of the first sections of the 580m, two-lane bridge's concrete deck over the next two months.

Yesterday's lift of the 22-tonne beam by two cranes, above a service platform reaching halfway across the river, came a year after Prime Minister John Key turned the ceremonial first sod on a project which the Government brought forward two years as part of a $500 million jobs stimulation package.

Although the four steel beams almost 6.5m above the river have become the most visible part of the project for motorists queuing to cross the adjacent 82-year-old bridge, the Transport Agency says contractors have also put considerable work into forming foundations for 2.5km of approach roads.

Because of the soft riverbank silt, the road foundations are being formed in layers, to allow for ground settlement of up to 2m.

Agency project management services manager Bryce Carter said about two years had to be allocated for that process, before the Coromandel's new gateway could be completed by mid-2012.

He acknowledged that the weight of the material loaded on the new formations had caused slumping in road approaches to the existing bridge, but said that was to be expected, and repairs were just part of the project.

The next big milestone will be construction of a large four-leg roundabout on firmer ground east of the bridge, to form a new intersection with State Highway 26 - the main route between Thames and Paeroa.

Mr Carter said that although the new bridge would remove a bottleneck, which on some holiday weekends has delayed traffic for up to three hours, there would still be pressure on the new connection at peak times.

Instead of drivers spreading out trips to allow for delays on the old bridge, traffic would become more concentrated at holiday peaks, so the roundabout would be built with two vehicle lanes to cope with the load.

The bridge will be built on 15 concrete piers, five of which have been completed. Five more are in various stages of construction on piles sunk up to 55m into the riverbed.

Lead contractor Heb Construction will work back from the middle of the river to its western bank, laying spans across the piers, before dismantling the service platform and recycling its materials for a similar exercise from the opposite bank.

One motorist, thinking the service platform was part of the new bridge, asked the Transport Agency why it was building another one-lane structure.

Although most of the bridge's spans will be 36.7m long, a navigation span intended to provide clearance for most boat traffic will be 42.8m across.

The Transport Agency is required by the Historic Places Trust to retain the existing low-lying bridge, which has Class 1 heritage status.

Mr Carter said local councils and Environmental Waikato would be consulted over whether a swing section on the old bridge would be kept open permanently for large boats to sail up and down the Waihou River.

He acknowledged that some local groups might see the old bridge as an attractive element of a walking and cycling network, but said the new structure was being built with a pathway for pedestrians and cyclists, and it would be costly to keep opening and shutting the swing section.