It won't be long before motorists get their first glimpse of a major upgrade of the Makatote viaduct on the North Island Main Trunk line.
A $13 million project will see lead-based paint blasted off the steelwork of the viaduct spanning the Makatote River about 12km south of National Park, to be followed by strengthening and repainting the structure which is more than 100 years old.
KiwiRail awarded the contract to New Plymouth-based firm TBS Farnsworth and the company has been on the job since September last year.
The contract is on track to be completed in November-December 2016.
Craig Comrie, the company's construction manager, heads a crew of up to 30 workers who are on the job seven days a week, in an environment he calls "challenging".
The contract calls for lead-based paint to be sandblasted off the 107-year-old viaduct, before steelwork is strengthened and the whole structure repainted.
KiwiRail is overseeing the project that also involves the Department of Conservation, Heritage NZ, local councils and iwi. DoC is involved because the area is a known breeding ground for the rare blue duck (whio).
It means TBS Farnsworth has to go to extreme lengths to make sure none of the paint coming off the viaduct has to be collected and taken off site for disposal.
Much of the work is being carried out inside a double layer of plastic wrapped around the viaduct. because at times the wind chill has been down to -14C.
Mr Comrie said that the team of workers had installed 52.5 tonnes of new steel on the five trusses supporting the viaduct.