Cougal Spiral and Tunnels, Kyogle, NSW

The Cougal Spiral is a heritage-listed single track railway tunnel and spiral feature of the New South Wales North Coast railway line that connects New South Wales with Queensland through Richmond Gap. It was built during 1930. It is also known as the Border Loop railway formation and landscape, Cougal To Border Loop and Railway Spiral and Landscape. The railway line needs to climb at a steady ruling gradient from Kyogle to the summit at a 1100 metre tunnel at the border between the two states. The border is also at the watershed. The rail spiral and associated facilities are located between 871 and 876 kilometres from Sydney Central railway station.

Cougal Spiral from the Border Loop Lookout

Climbing almost non-stop at the ruling grade of 1 in 66 or 1.5% (compensated) the line has almost continuous curves of 240 metre 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 without having to make any forward progress. Soon after the Border Tunnel under the watershed is reached the line descends on the other side. The spiral has two short tunnels (192 and 177 metres long), 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 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 railway spiral at Border Loop is one of only two railway spirals in NSW.

The Cougal Spiral is easily viewed from parts of the Lions Road. The completion of the Cougal to Border Loop section of the North Coast Railway was a major engineering feat in the first half of the twentieth century, being one of several major engineering projects in NSW that allowed continuous railway access between Sydney and Brisbane. Consequently, the structure has been heritage listed due to its historical, scientific and architectural rarity. It opened on 29 August 1930 as part of the extension of the North Coast line from Kyogle to South Brisbane.



As at 19 July 2013, the Cougal to Border Loop section of the North Coast Line has been classified as a notable engineering achievement, revealing a twentieth century engineering solution that allows trains to pass through the steep topography at the NSW/Queensland border. Border Loop railway formation and landscape was listed on the New South Wales State Heritage Register on 2 April 1999.