Campaign In the 1900s it became increasingly clear that the single-track tunnel, despite having a double-track line at the northern end, was creating significant 'delay, discomfort and danger'. The
Minister of Railways,
Joseph Ward, argued that his staff had convinced him that it was not [yet] essential to duplicate the tunnel to remediate the delays. However, in a strange twist, he moved at the end of a meeting with a 200-strong citizens deputation that if "ten representative [business]men", selected by the
Mayor of Auckland, would traverse the section with him, and then ask for the tunnel duplication, he would be willing to proceed with it. In the end, in 1911, only 7 of them recommended duplication, with 3 opposed. The opposition was possibly caused by the concern that the tunnel duplication would prevent a
goods shed expansion, and because it had been advised that timetabling could work around the limitations of the single-track tunnel. Government had previously argued that up to 240 trains daily (one every 6 minutes) could be run through the single-track tunnel, and thus, the cost of £35,000-£40,000 for the duplication was not merited when other projects were of greater importance. Due to the lack of unanimous agreement – and because the Railways Department argued the tunnel could take twice the traffic using it at the time – duplication was again declined. However, there was considerable discontent in Auckland during the 1900s and 1910s that the government was proceeding with major tunneling works in the
South Island, such as at the
Otira Tunnel to
Arthur's Pass, while arguing that there was no funding available for the Parnell Tunnel. Groups like the
Auckland Chamber of Commerce lobbied strenuously for the duplication. At the same time, proposals to either take a new line up
Grafton Gully, or build a new line via
Ōrākei (which was eventually constructed as the
Eastern Line), thus avoiding the almost 1:50 gradient up to the Parnell Tunnel, may have contributed to doubts as to whether the tunnel should be duplicated. There was also a perception by the minister of the day that additional freight traffic generated by the
North Auckland Line would not be worth considering as an argument for the tunnel, as it would be extremely limited. While duplication was finally noted as 'definitely agreed' in 1912, funding was not immediately found. However, the impending move of the engine sheds for the railway from
Auckland Railway Station to the
Newmarket Workshops also increased pressure to ensure the duplication.
Construction A new tunnel, able to carry a double set of tracks, was finally built over the 1914–1915 period. The first preparatory works occurred around April 1914, widening the approaches to the tunnel, and the first air shaft connecting the two drives was pierced through in January 1915. From initially 50 people, the workforce had by then expanded to 140. Stormwater drainage was also improved as part of the work, with the insufficient quality of the drains (and the earlier attempts to fix them) having forced authorities to place speed restrictions on the tunnel in the past. == Incidents ==