The Parnell railway bridge was originally constructed between 1865 and 1866. Although the superstructure has been replaced, the original piers remain and it is believed to be the oldest railway bridge still in use in the North Island. It was to be part of the ill-fated Auckland to Drury Railway Project. The project proposed giving access to the Drury and Waikato coalfields south of Auckland, and providing a supply line to the military forces engaged in the Waikato Land Wars in 1863-1864. The bridge was to be the first part of that project involving a link between Mechanics Bay and the Newmarket settlement. Unfortunately, time and cost over-runs resulted in abandonment of the project in 1866 and it became locally known as the ‘bridge to nowhere’.

The construction involved a bowstring truss bridge with a viaduct over Parnell Rise, all supported on large basalt piers. They were built in a monumental style for the period with mortar bonded ashlar masonry concealing rubble backing. It was unusual for early railway bridges to feature basalt as a construction material. It is still in good condition except for some mortar cracking due to vibration at the top of a southwestern pier. It has technological value for retaining elements of major engineering achievement from our early colonial history and reveals information about construction, quarrying and other techniques of construction.

It remained a costly ‘white elephant’ until Prime Minister Sir Julius Vogel’s public works policies came into operation in the 1870s. During this time it was reclaimed and became the first part of Vogel’s railways to be operational and run by the government. Modifications were made in the 1890s and some masonry piers were raised in height. Between 1908 and 1909, substantial modifications were made and the entire superstructure was replaced with a 39m span double-intersection Warren truss with overhead ties. Two piers were removed to widen the roadway and the remaining piers widened for double track rail. The construction was of identical style to the original. It was completed in 1909 when the main trunk railway between Auckland and Wellington was opened.

It is interesting to note that the original 1860s rail gauge was 1435mm wide for a single track, but this was later replaced with the present, narrower 1067mm gauge.

The Parnell Railway Bridge remained part of the main trunk link until the Orakei to Westfield deviation eventuated in 1930, but has remained in daily use for suburban trains with only some rail replacement. In 1974 overhead ties were added to the truss. The aesthetic value of the monumental appearance is largely concealed today by advertising hoardings.