The community relies heavily on a network of roads, bridges, tunnels, railways, ports, airports and public transport. However, as Australia and New Zealand’s populations soar, these assets will come under increasing pressure, requiring an innovative and efficient approach to maintenance and remediation.
The need to address the gaps in today’s transport infrastructure was recently highlighted in a report by Infrastructure Australia. While the latest Budget 2018-19 included a substantial commitment for transport infrastructure projects, there are calls to ensure smarter technologies are used to keep construction and maintenance costs in check. Yet it is an immense task; in New South Wales alone, 128 local councils are responsible for managing approximately 165,600 kilometres of roads, not to mention an expansive public transport network.
Ground engineering continues to play a significant role in identifying issues that commonly affect the stability of major roads, bridges, tunnels and public transport networks and is, in many instances, responsible for delivering solutions to extend the life of these vital assets.
Mainmark is frequently called upon to remediate a wide range of infrastructure without disrupting the day to day transport network operation, or impacting the communities that rely on them. Each project is unique in terms of scope, location and accessibility, and requires an appropriate and bespoke solution.
Following are a few innovative and customised solutions used by Mainmark to remediate transport infrastructure in Australia and New Zealand.
Supporting roads, highways, bridges and transport yards
Teretek® engineered resin injection is a proven and commonly used solution for repairing ground subsidence affecting bridge approach slabs. Subsidence on the roadway approach due to heavy vehicle use can cause the surface to sink into the ground, disrupting the smooth transition between the roadway approach and the bridge. Mainmark’s highly efficient process to re-level the approach is achieved by injecting the engineered resin into the road sub-grade, filling any voids to create a solid supporting foundation for a smoother transition for vehicles. The solution is cost effective and quick to apply, minimising traffic disruptions.
Fonterra, one of New Zealand’s largest companies, had experienced subsidence at one of their busy transport yards. Unstable soils and voids under 150mm-thick concrete slab had caused approximately 100m2 to settle by as much as 50mm. Utilising Teretek, Mainmark was able to fill the voids and lift the slab back to level with minimal impact to the site’s daily operations.
Pipe decommissioning beneath major intersections and airport runways
Mainmark’s Terefil® can assist road operators to decommission redundant pipes and culverts located beneath road networks and runways. Terefil was used to completely fill a 450mm, 390m long low-pressure gas pipe underneath an extremely busy intersection in Melbourne’s St Kilda. The pipe needed to be safely decommissioned as part of a tram service upgrade and streetscape renewal project led by local transport authorities and local council. Using Terefil resulted in significant time and cost reductions, enabling trams to resume full service one week earlier than anticipated.
Mainmark also assisted Brisbane Airport to remediate a culvert beneath an operational runway, which was first sealed with Teretek resin injection then filled with Terefil. This was accomplished quickly and efficiently, despite the busy operational airfield environment and limited access to the aircraft pavement where the culvert was located.
Stabilising railway tracks and underground lift shafts
When two newly constructed lifts to the underground concourse and platforms at Museum railway station on Sydney’s City Circle train line required stabilising, Mainmark used Terefil to support the rock surrounding the lift shafts by eliminating voids. This provided a safe, stable and reliable solution that caused minimal disruption to pedestrian access within and around the railway station.
In another railway project, Teretek resin injection was used to fill large voids that had formed beneath the track slabs of the 8.8km Kaimai Tunnel, New Zealand’s longest railway tunnel. A specially formulated grout was then used to bond the subgrade to the slab and re-support the railway track. The early intervention helped to prevent extensive damage to the tunnel floor, avoiding potential closure and a costly slab replacement, while also preparing the tunnel to accommodate larger and heavier trains in the future.
Efficient and timely renewal and maintenance is crucial to ensuring the longevity of transport infrastructure. A smart approach can also avoid budget blowouts, limiting the inconveniences and commuter/traffic distruptions. In some cases, ground engineering solutions and technologies can also help to reduce the need to replace major transport infrastructure.
By Laurie Andrews
Laurie Andrews is Mainmark’s Business Development Manager for NSW & ACT. Laurie is a qualified civil and structural engineer with nearly 30 years experience working in the construction and engineering industry.