The mighty KB Series locomotives were king of the rails in the era of steam, and a familiar sight in Rolleston

The iron highway west

by Andy Bryenton

For many years, Rolleston was famed as the junction between two of the most important rail lines in the South Island. Here, the main south line met the midland line, a railway that was conceived with a courageous vision and has given New Zealand one of its great overland sightseeing journeys.

The idea of a rail line to link Canterbury to the coal and timber wealth of the west coast was put before a royal commission in 1883 but rejected as uneconomical.

In the way of the line stood the Southern Alps, along with the rugged Broken River and Waimakariri gorges, described by District Engineer W.N. Blair as “very rough, the mountain slope rises from the riverbed while the river runs in a fearful gorge all the way”.

Those early railway engineers were undaunted, and pressed on, constructing viaducts and tunnels to rival anything Isambard Brunel crafted in Britain. The Staircase Viaduct, for example, lofts the rails 75 metres above a fast-flowing torrent. The Otira Tunnel is more than eight kilometres long, passing under the mountains to Arthurs Pass township.

The locomotives that would ply this line from Rolleston to the coast were as mighty as the structures completed to forge their path. Perhaps the kings of them all were the KB series, colossi of the rails designed to tackle the steep gradients and heavy goods trains which were the norm for the midland line. More than 10 metres long, equipped with a secondary booster motor, and delivering in excess of 1,400hp, the KB class engines were a sight to behold as they steamed out of Rolleston on their way across the spine of New Zealand.

Today, the line is home to the famed TranzAlpine service, acclaimed as one of the great rail voyages in the world. It’s 212 kilometres of history and stunning scenery, which is anchored at its eastern end by Rolleston.