The iconic Illawarra Escarpment is synonymous with Wollongong but navigating it back in the day was no easy feat. A lot of the roads still used to manage the steep descent from the escarpment to Wollongong were built many years ago to service mines and other heavy industries
It means upgrading roads like Harry Graham Drive at Mount Kembla, built through cut-and-push methods in the 1940s, requires innovative engineering solutions to guard against rock falls and address stability issues.
Council has undertaken several phases of stabilisation works to the road over many years with its location on the escarpment, susceptibility to rockfall and landslide pressures, and proximity the high-pressure Eastern Gas Pipeline presenting several project design challenges.
For the latest upgrade, Council’s geotechnical, structural and survey teams were able to utilise data from slope and groundwater instrumentation wells, investigations, and their extensive experience to develop a robust, practical in-house design to stabilise 275 metres of embankment and roadway between Wollongong Motorcycle Club and Kembla Village.
Technical modelling enabled progressive adjustment to the design to meet site conditions, while minimising construction vibration via in-place monitoring to avoid impacting the Eastern Gas Pipeline.
The design approach uses staggered sheet piles and a concrete torsion beam, which builds on the design from the stabilisation works on two previous sections of the road that have performed well through several natural disasters and resulted in significant time and cost savings compared to alternative options.
Works have also included new road pavement, new drain outlets, a new concrete swale, and installation of a traffic barrier on the outside of the embankment. The project is now complete – with only line-marking to be carried out – and will see the road revert to two lanes and provide improved access to the Mount Kembla mountain bike trails recently opened by National Parks and Wildlife Service.
Lord Mayor of Wollongong Councillor Tania Brown welcomed completion of the complex works.
“Our location between the escarpment and the ocean is what makes Wollongong such a beautiful place to call home, but it does present different challenges given the susceptibility to slope instability,” Cr Brown said.
“We’ve seen that through several declared natural disasters in recent years, which have obvious impacts on the roads that run up and down the escarpment. It heightens the risk of rock falls and landslips so it’s very important that upgrades to these roads, a lot of them built many years ago, are carefully carried out.
“I commend our engineering team for coming up with a project design that addresses the unique challenges presented and to complete these works efficiently while ensuring its long-term resilience and safety for road users.
“Boosting tourism opportunities and positioning Wollongong as an adventure sports destination is a major priority for Council. Upgrading roads to ensure people have safe and reliable access to the new mountain bike trails at Mount Kembla are essential to those goals.”
