Rejuvenation of the heritage Makatote rail viaduct

PROJECT DESCRIPTION

Makatote rail viaduct is located in the North Island of New Zealand. It is one of the tallest railway viaducts in the country and holds significant heritage value for its elegance and the technology used at the time of construction (circa 1908). The viaduct began to suffer from corrosion, which subsequently led to section losses of steel elements. With an additional desire to upgrade the viaduct to the future load requirements of KiwiRail, the viaduct was refurbished and strengthened to extend its life for another 50 years.

Judge's comment:

The Makatote Rail Viaduct was deteriorating badly due to corrosion, resulting in loss of strength through oxidation of the steel structure.

A business case was prepared as to the economical viability of refurbishing the viaduct compared to building a new viaduct. Even allowing for maintaining the viaduct in service during refurbishment, the refurbishment financial costs were less than half the cost of a new valley crossing. Since the viaduct is a Category 1 structure of Heritage New Zealand, it would be mandatory to preserve the viaduct in some form which would require on-going maintenance and be a further cost to the new viaduct option. Having chosen the refurbishment option, there was close collaboration with the contractor from the onset of the project to ensure good value for the client. This led to no surprises onsite when construction was underway, saving time and in turn money for the client.

The judges recognised that the good economic sense of the refurbishment only became outstanding value when the design was so sensitively, elegantly and expertly delivered that the heritage aspects of the viaduct have been maintained for future generations. This, together with the environmental sensitivity in the specification of the works and the avoided environmental impacts of a new viaduct, mean this is a project is of outstanding value to the client and also society.