Rejuvenation of the heritage Makatote rail viaduct

Structural Designer

Opus International Consultants

Client Name

KiwiRail

Location

New Zealand

PRINCIPAL CONTRACTOR: TBS Farnsworth

ARCHITECT: Heritage New Zealand            

PROJECT MANAGEMENT AND CONTRACT ADMINISTRATION: 41 South

INDEPENDENT COATING INSPECTOR: Pacific Corrosion Consultants

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 rejuvenation of the 109-year-old Makatote railway viaduct provided a magnificent historic structure with a new lease of life that will take it well into the 21st century. The viaduct stands 79m high and is 262m long and was constructed at the dawn of the 20th century. Its fine lattice steel structure had suffered from the ravages of time and the demands of modern trains, leaving its future in doubt.

Rather than replace the structure with a new valley crossing, the engineers were convinced the viaduct could be given a new lease of life. Over 15,000m² (about the area of two football pitches) of old lead paint were carefully removed and vacuumed away to avoid contaminating the rich natural environment below which was home to nesting Whio (an endangered Kiwi duck). The surfaces were then repainted with an advanced paint to last another 50 years. The lattice steel structure was subtly and skilfully restored and enhanced, increasing the load capacity by 25% to accommodate new, heavier trains. There is virtually no visual clue to the strengthening regime and lthe elegant clean lines of the original structure are completely unspoilt.

In all, the project represents a triumph of engineering-led conservation that leaves the vision of 19th and early 20th century railway men unspoilt for 21st century generations to enjoy.