Bethungra Spiral

The Bethungra Spiral is a heritage-listed rail spiral in Australia, built on the Main South line of New South Wales at Bethungra in the Melbourne → Sydney track between Junee and Cootamundra. It was added to the New South Wales State Heritage Register on 2 April 1999.

The Bethungra Spiral is proposed to be bypassed by the Inland Railway project on a new alignment with an easier grade by 2025.

History
The original line was graded at 1 in 40 for Sydney bound trains, which imposed a severe limitation on train loads, and also caused congestion as bank engines were attached.

When the line was duplicated in the 1940s, an 8.9 kilometre spiral deviation was built. The spiral makes use of local geography in the shape of a convenient hill which the uphill line spirals around and has short tunnels. The spiral increased the distance travelled by uphill (northbound) trains by about two kilometres. Downhill (southbound) trains continue to use the original line. The ruling gradient of the new uphill line is 1 in 66.

Due to the extensive blasting required to create 27 metre cuttings through granite, the line suffered from rockfalls with twelve significant falls between 1960 and 1987. In January 1994, the spiral line closed for a four-month rebuild which saw the cuttings widened and regraded to benched 55 degree slopes as part of the One Nation project.

Heritage listing
The Bethungra Spiral is of high significance illustrating a means of ascending a significant mountain range with easier grades than the original (now down the main line). It is a major civil work and an ingenious engineering solution using the technology available at the time of construction. The site has major landscape value.

Bethungra Spiral was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria: The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales. This item is assessed as historically rare. This item is assessed as scientifically rare. This item is assessed as arch. rare.

Description
Starting at the lower left corner of the interactive map, the up-track to Cootamundra (and thence to Sydney) is the one on the left. It has been given a less steep gradient than the down-track so is able to pass under it (through a tunnel) then through another tunnel before sweeping around, gaining elevation all the while until crossing over itself at the second tunnel. It is now higher than the down track and on its right, and at a grade separation further north (click on "Full screen" to view) crosses over to the left and eventually the two arrive at the same level.

Tourism
A traveller who has just passed through Bethungra township on the way to Cootamundra would be unaware of its existence nearby, to the right of the road, as there is no signage or safe off-road parking to observe the two rail lines at three elevations.