Rimutaka Tunnel the first fully dieselised line in New Zealand. Today, DBR, DC, DFT and DX class locomotives run the route. There have been proposals to electrify the tunnel and the Wairarapa line as far north as Masterton as an extension of the Wellington suburban electrification. The tunnel was designed to enable catenary to be installed but this has not happened, and the catenary finishes just north of Upper Hutt station. In 2007, Greater Wellington Regional Council rejected a call to electrify the tunnel, on the basis that patronage did not justify the expenditure, and that the tunnel would "have to be
Rimutaka Tunnel and a width of 4.68 metres (15 feet 4 inches); it is lined with concrete with a minimum thickness of 38 cm (15 inches) inside the face of the excavation. When the tunnel holed through on 20 April 1954 the surveying error was found to be only 44.5 mm (1.75 inches). The tunnel was planned to reduce the distance between Upper Hutt and Featherston from to . After its completion, a 2.74 metre (9 ft) diameter vertical ventilation shaft was driven up from a point almost halfway through the tunnel. It reaches the surface beside the Remutaka Rail Trail near