Tawa Flat deviation

The NIMT Tawa Flat Deviation's double-track climbing towards Tawa No. 1 tunnel over the up Wairarapa Line and Hutt Rd, with Ngauranga station in the background alongside the State Highway 1 motorway.
Map
Map

The 8.38 miles (13.49 km)[1] Tawa Flat deviation is a double-track section of the Kapiti Line just north of Wellington, New Zealand with two tunnels; the southernmost section of the North Island Main Trunk railway (NIMT) between Wellington and Auckland. It was built to bypass a limited capacity single track section of the original Wellington and Manawatu Railway (WMR) line which ascended from Wellington to Johnsonville and then descended to Tawa Flat. The original name of Tawa Flat was changed to Tawa in 1959.[2]

When opened to passenger trains in June 1937, the deviation reduced the travel time from Wellington to Porirua by 15 minutes, to 27 minutes rather than 43 to 48 minutes.[3] [4] By 2016, the time from Wellington to Porirua had further reduced to 21 minutes for stopping trains, despite extra stops at Redwood, Linden, and Kenepuru which each add 48 seconds to the travel time, and to 17 minutes for non-stopping trains.[5]

  1. ^ Railway Magazine February 1934 pp. 100-105
  2. ^ Carman 1970, pp. 234–235.
  3. ^ Murray 2014, p. 151.
  4. ^ Murray & Parsons 2008, p. 33.
  5. ^ Metlink Kapiti Train Line timetable effective from 20 January 2016