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, situated 792m above sea level and one of the tallest bridges in the country, was deteriorating badly due to corrosion, resulting in loss of strength through oxidation of the steel structure. By carefully cataloguing and assessing the structure, the engineers were able to present a clear business case to the client for refurbishment and strengthening of the original skeleton, rather than opting for construction of a new viaduct. The project’s success was enhanced by involvement of the chosen contractor at an early stage, resulting in a close partnership to develop construction methodology that would allow continuous use of the viaduct throughout the restoration works.

Elegant, non-intrusive detailing of the strengthening procedures, such as new tension rods hidden behind existing structural members, mean that the heritage aspects of the viaduct have been fully maintained, while enabling increased loading from modern railway traffic. Environmental requirements have also been fully respected, in particular with regard to the removal of the original lead based paint, carried out under strict encapsulation and closely monitored. Strengthening was designed to be installed manually, and components were chosen carefully to allow for replacement of inadequate members in the interval between trains.

The result is a new lease of life for an iconic heritage viaduct whose aesthetics are fully maintained while its performance has been upgraded to comply with modern loading and safety requirements.