There have been a number of proposals to build a Taupo Line as a branch railway linking the township of Taupo in the central North Island of New Zealand to New Zealand's rail network. One proposal proceeded as far as the construction stage before being stopped.
By 1952, nearly every main centre in New Zealand was served by a railway, the exceptions being Kaitaia, Queenstown and Taupo. Taupo is one of New Zealand's biggest forestry centres and is a very popular tourist destination.
The first time consideration was made to link Taupo with a railway was in 1884 when routes for extending the North Island Main Trunk (NIMT) railway south from Te Awamutu to Wellington were being explored and surveyed. One of the proposed routes was from just south of Te Awamutu following the course of the Puniu River inland through to Taupo, and onwards east to link at Hastings with the proposed Palmerston North - Gisborne Line. This route did not eventuate and the present route via Taumarunui was chosen.
In 1903 the Taupo Totara Timber Company (TTT Co) constructed an 82 km tramway to link their milling centre at Mokai with the New Zealand Government Railways line (NZR) at Putaruru. The line was built over the former Lichfield Branch line, which was originally built by the Thames Valley and Rotorua Railway Company to be part of the line to Rotorua. The TTT Co line then went onwards south of Lichfield through what are now Tokoroa and Kinleith and crossed the Waikato River at Ongaroto.
At Ongaroto the company built a large timber bridge of locally sourced totara, designed by Public Works Department engineer Frederick Furkert. In later years this timber bridge deteriorated and was condemned, but the company could not afford to replace it immediately because its sawmill had burned down in 1928. In the last few years of service, trains arriving at the bridge would stop and the passengers and fireman would walk across while the driver gently opened the throttle and then jumped off. The train would slowly ease across the bridge before being stopped on the other side by the fireman, where everyone would reboard the train. This bridge was replaced in 1931 by a steel truss bridge with a central pier.