Although the New Zealand railway system is predominantly single track, with crossing loops at stations, double-line working has been made possible as a result of duplication in several areas where traffic density is exceptionally high. More than 157 route miles of double track were in use at the end of 1964 on the approaches to Auckland, Wellington, Christchurch, and Dunedin. The section between Auckland and Frankton, which carries the highest density of traffic in New Zealand, is duplicated for almost its full length of 84 miles. The task of reconstructing the railways to meet modern needs is a never-ending one. The financial stringencies of the seventies and eighties, and later, resulted in economies of construction that today seriously hamper railway operations, and deviations are necessary to shorten distances, to reduce severe curvature, or to eliminate steep gradients. Old bridges – some dating from the earliest days of railways in this country – enforce restrictions on modern locomotives which are quite unacceptable, and in most instances such bridges are no longer economical to maintain in good condition. As rapidly as finances and engineering considerations permit, they are being replaced by new structures designed to have a very long life combined with low maintenance costs. New Zealand railway engineers are making increasing use of prestressed concrete as a construction material, and it would appear that the concrete railway bridge will in the future become as commonplace as was once the timber bridge in the nineteenth century.
Each of the four main centres – Wellington, Auckland, Christchurch, and Dunedin – now possesses a large and well-planned passenger terminal. The newest, at Christchurch, was completed in 1960. At many of the provincial centres, and at some country towns, the traditional rambling wooden station building has been replaced by a neat and functional structure of contemporary design. It would be premature to state that the replacement of old and inadequate station buildings is planned on a large scale, but the trend is a continuing one, as is shown by the recent construction of attractive stations at Rotorua, Te Awamutu, New Plymouth, Stratford, Napier, Palmerston North, Feilding, Lyttelton, Springfield and Port Chalmers. Many new goods sheds are also being built, particularly in the Auckland district, where an expanding economy is taxing existing facilities. To reduce manual work, greater use is being made of mechanical appliances such as mobile cranes and forklifts. At Frankton a new trans-shipment shed with freight trolleys propelled by an underfloor endless chain was opened in 1960, and at Westfield, on the outskirts of the Auckland metropolitan area, an extensive new marshalling yard costing more than £700,000 was brought into use in 1962. Elsewhere, crossing loops and station yards are being lengthened or otherwise increased in capacity to accommodate the bigger freight trains that diesel locomotives have made possible.