Expert ‘tweaks’ deliver innovative road solutions

Innovation in engineering does not have to involve step change to make significant impact, according to Queensland’s EDG Consulting. It can be about applying experience and expertise to achieve the incremental changes that can add up to big time and cost savings for a project, says senior principal Greg Hackney “The innovation in what we do day to day is to use probably what are relatively well-accepted practices and look where we can tweak or develop those practices to give a better outcome,” he said. EDG won a gold award at this year’s Consult Australia Awards for Excellence for its work on the Sarina Range road reconstruction. Its approach to the challenges in restoring the crossing after severe damage from landslides during Cyclone Debbie (2017) saw it win the Business Innovation - Small Firm category. “It is recognition that the approach we take to deliver good outcomes to our clients actually works,” Mr Hackney said of the honour. “It does mean good outcomes.” EDG Consulting was engaged by Queensland’s Department of Transport and Main Roads to provide remedial works designs for 25 affected sites along the road. No prescriptive design standard is available for remedial works from natural disasters in Queensland, and the terms of federal National Disaster Relief and Recovery Arrangements (NDRRA) funding limit the improvements that can be made. A damaged section of the range road before the remedial works. The project’s award submission highlights how EDG Consulting’s design criteria took into account the mechanisms that led to the landslides, the risk profile for each site, and the site-specific issues such as construction access and space for reconstruction works. The objective of the innovation was to develop practical, bespoke design requirements that resulted in remedial works that could be undertaken in a timely and cost‑effective manner. The criteria they came up with ultimately provided for a road geometry that was similar to the pre-disaster standard, but with an improved resilience to future rainfall events. Examples of the solutions implemented on the Sarina Range include: Regrading of cut batter slopes to flatter angles than in the pre-disaster state, thus reducing the potential for future landslides and debris from landslide reaching the traffic lanes. The application of alternative design criteria allowed a balance between batter slope angle and risk, reducing earthworks and the works footprint significantly whilst still improving the assessed risk for road users.Where no space was available for cut slope regrades, rockfill buttresses and soil nails were used to provide slope support to areas where failures occurred, allowing the works to stay within the road corridor boundaries. Failed road embankments that were previously constructed with uncompacted earthfill have been reconstructed using compacted rockfill on a prepared foundation. The use of rockfill enabled the use of steeper batter slopes and provided an embankment that drains more effectively and is therefore more resilient to future events. Steeper sections of road embankment and cut slope have been supported using retaining walls anchored into the slope or soil nails, reducing the scale of the remedial works, compared to unsupported steep batter slopes.Improvements to drainage enable surface runoff water to be removed more effectively from the site, thus reducing the potential for future instability. https://www.i-q.net.au/main/ring-road-work-rolling-out-for-townsville

Expert ‘tweaks’ deliver innovative road solutions

Industry Queensland

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