Cougal Spiral (railway)

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Cougal Spiral
Up Brisbane Mail crosses over number 5 spiral tunnel.jpg
Up Brisbane Mail crosses over No.1 Spiral Tunnel
Other name(s) Border Tunnel
Border Loop Spiral
Line North Coast Railway
Location Richmond Gap connecting New South Wales and Queensland, Australia
Coordinates 28°21′16″S 152°57′51″E / 28.354390°S 152.964038°E / -28.354390; 152.964038Coordinates: 28°21′16″S 152°57′51″E / 28.354390°S 152.964038°E / -28.354390; 152.964038
Length A series of three tunnels:
  • 192 metres (630 ft)
  • 177 metres (581 ft)
  • 1,160 metres (3,810 ft)

The Cougal Spiral is a heritage-listed single track railway tunnel and spiral feature of the North Coast Railway in Australia that connects New South Wales with Queensland through Richmond Gap. The railway lines needs to climb at a steady ruling gradient from Kyogle to the summit at a tunnel at the border between the two states.[1] The border is also at the watershed.


Expo Express crosses Gradys Creek Bridge No.5

Climbing almost non-stop at the ruling grade of 1 in 66 or 1.5% (compensated) the line has almost continuous curves of 240 m (790 ft) radius. Near Cougal, the alignment finally runs out of valley, and has nowhere to go. Fortunately a convenient hill allows the line to circle back on itself so that it climbs 30 metres (98 ft) without having to make any forward progress. Soon after the Border Tunnel under the watershed is reached, and the line descends on the other side. The spiral has two short tunnels, one where it passes under itself, plus another through a small spur in the hillside.

The tunnel at the border summit is approximately 1,600 metres (5,200 ft) long, broken up into three separate tunnels. A lower summit, perhaps without the spiral, would be possible with a considerably longer and more expensive summit tunnel, with the possibility of problems with fumes for both the original steam locomotives and the replacement diesel engines.

The Cougal Spiral is easily viewed from parts of the Lions Road. The structure has been heritage listed due to its historical, scientific and architectural rarity.[1]

See also[edit]


  1. ^ a b "Cougal To Border Loop, Railway Spiral and Landscape". New South Wales State Heritage Register. Office of Environment and Heritage. Retrieved 11 September 2017.