G. Matthews¹, M. Keenan², D. Jansen2
¹TBS Group, New Zealand, ²Structures Engineering Services, KiwiRail, New Zealand
The Makatote Viaduct is on the North Island Main Trunk (NIMT) Railway line, which is a 680km long railway that connects Auckland and Wellington, the two major cities in New Zealand (NZ). Due to both natural and man-made difficulties it took nearly 40 years to finally complete the whole route. The railway passed through some of the most challenging terrain in the North Island and required engineering ingenuity to complete. Additionally, there was resistance from the local Iwis, who were against the settlement made between the tribal leaders and the Government.
The viaduct was one of the last pieces to be completed on the route, which was opened in 1908. At 78m above the stream it was the highest structure on NIMT until 1981. Its elegant tall and slender steel trestle piers with lightweight trusses rising through the gorge with the backdrop of National Park have made it an iconic structure (Figure 1). It has been one of the most photographed steel rail viaducts in New Zealand. The Viaduct has been assessed for and found to possess aesthetic, historical, social and technologically significant values.
When the viaduct celebrated its centenary in 2008, it became apparent that the structure required refurbishment to extend its life and improve the resilience of the NIMT. To this end KiwiRail commissioned contractor TBS Farnsworth and design engineers Opus International Consultants (Opus) to undertake a detailed load assessment, strengthening and repairs to improve the load capacity and repainting of the entire viaduct. The physical works commenced in September 2014 and was completed in October 2016.
This paper presents the details of this work together with some critical challenges overcome on site.