SH 20 Motorway Extension – Bridge 4 SH 20 over North Island Main Trunk Rail Line.

BBR Contech was awarded a contract to supply, install, stress and grout 9 very large capacity post tensioning tendons into the piers of a rail overpass bridge being constructed as part of a new motorway connection between the main Southern Motorway SH 1 and the North Western Motorway SH 20, in Manukau City. This work is being undertaken to provide an alternative ring road to allow motorists to by-pass Auckland by travelling along a motorway to the West of Auckland City.

The tendons each consisted of 31 number by 15.6 mm diameter stressing stands which have an ultimate capacity of 775 tonnes and which were stressed to 620 tonnes each. These tendons are some of the largest tendons ever installed in New Zealand.

The post tensioning was carried out on the partially completed bridge in close proximity to the North Island main trunk rail line which remained active during the stressing operations.

This project represents the first use of the new BBR VT Cona CMI internally bonded post-tensioning system, in New Zealand.