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Cambridge section

All about bridge buildingBridge construction is a big part of the Cambridge section of the Waikato Expressway. There are eight bridges nearing completion including a viaduct over the Karapiro Gully, various under and over bridges for local roads and the interchange structures. The top section of the deck is made up of a number of components using a combination of materials such as steel and concrete.

The Northern interchange bridge was the last of the four steel bridges to have all the beams craned into place. All beam lifts are now complete on the project. This also means the first component of all the bridge superstructures is complete.

DID YOU KNOW?

Pavement on bridges is different to the main alignment pavement due to the concrete deck of the bridge providing a rigid foundation. This means the pavement surfacing layer can be applied directly onto the concrete bridge deck without the need for underlying granular pavement layers.

SUPERSTRU

CTU

RESU

BSTRUC

TURE

FOUNDATION

WHAT IS THE SUPERSTRUCTURE?

The superstructure section of a bridge is the part of the bridge that rests on the pier and abutment caps. The components which make up the superstructure include; beams placed to form the length of the bridge and girders placed across the beams which the bridge deck is then constructed on.

Steel was selected on four of the eight bridges for this project due to the long spans required and to keep the superstructure light and able to support shallow footing substructures.

To build the bridge deck, precast concrete deck panels are laid across the bridge and reinforcing steel is installed before concrete is then poured on top. This is the form of all steel bridges on the Cambridge section including the Northern interchange bridge, Karapiro Gully viaduct, Victoria Road interchange bridge and the Southern interchange bridge. Lastly barriers are installed.

SURFACINGOGPA

GEOTEXTILE/GEOGRID

BASECOURSEDENSE GRADED ASPHALTSUBBASEBITUMEN

SILCONCRETE BRIDGE DECK

SUBGRADE

TYPICAL PAVEMENT LAYERS ON BRIDGE

TYPICAL PAVEMENT LAYERS ON MAIN ALIGNMENT

Southern interchange bridge deck steel reinforcing.