Road engineering techniques to become a sustainable living city

Mar 18
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In this short article Peter Levett of the City of Salisbury details the modern engineering techniques that his team and council are investigating and implementing as the work towards creating a sustainable living city.

A sustainable city doesn’t just mean recycling or reusing waste materials, instead it means investigating and adopting best practice and innovation. In our drive towards becoming a sustainable living city The City of Salisbury have been investigating the long term benefits of crack sealing, pavement preservation, micro-surfacing, spray seals, mill and fill asphalt, stabilisation and asphalt overlay.

We are currently engaged in a collaborative approach investigating the benefits of stabilisation with The University of South Australia, the City of Adelaide and the City of Playford. We are also involved in a long- term study with The University of South Australia’s School of Natural and Built Environments, The University of Wollongong and the Australian Research Council to investigate the role of vegetation and associated root suction and reinforcement on the stabilisation of transport corridors and sloping ground. Finally, we are also participating in investigations into the benefits of TREENET inlets with TREENET and The University of South Australia.

The impact of naturally occurring ground moisture and from leaking water utility infrastructure is significantly affecting the serviceable life expectancy of asphalt by deformation and collapse. Streets where micro-surfacing has been applied appear to be less affected by moisture or collapse through fracturing of the surface of old treatments from aging/oxidization, which is not generally expected with modifications to current micro-surfacing techniques.

Thanks to the promotion of Salisbury as a living city more residential redevelopments are occurring with older houses being demolished and land subdivided into two or more individual lots. Land parcels owned by council and developers are also being subdivided and redeveloped. While this process is affecting the road network, asphalt as the most costly treatment is less of a benefit in managing The City of Salisbury’s road network.

In these streets multiple housing developments can occur that significantly affects ride- ability, with recently asphalted streets early in its life being excavated and patched, thereby shortening the asset’s service life. Trees are an essential part of a living city, they cool and aesthetically improve the wellbeing of the community and increase the bird and animal life. Unfortunately, tree roots can deform the road surface, but the flexibility of micro-surfacing has been beneficial in increasing the time period until surface failure occurs and rectification is required.

*Micro-surfacing at the City of Salisbury (photo provided by Peter Levett)

It is a short sighted, costly and outdated process to wait until the asset has reached the end of its service life with no preventative maintenance only to demolish and rebuild. Instead our approach to strategic decision making of road treatments is to adopt a proactive and preventative maintenance mindset. For example, most people maintain their house by filling cracks, repainting and repairing damages when necessary over time. Managing a home is similar to Council’s decision making about new and maintaining existing roads.

Micro-surfacing as a road network treatment type is worthy of consideration. For many years this treatment has been used in Australia on rural roads and in recent years investment in preserving residential streets has been increased. Micro-surfacing reduces the impact on residents accessing their properties and significantly reduces the time for completion when compared to an asphalt overlay solution.

At the upcoming Road Engineering and Maintenance conference, running 18th & 19th April in Sydney, Peter Levett and Kazim Darwish from the City of Salisbury will go into more detail about micro-surfacing techniques to reduce asset renewal. They will be comparing performing to other products as well as looking at application techniques.

Submitted by Peter Levett

Peter Levett is a highly experienced practitioner in civil and landscape design, construction and maintenance with over 30 years’ experience in local government public works with major metropolitan Adelaide councils.

In his current role at City of Salisbury Peter administers a significant road resurfacing program across a network of some 760 km and other civil works. He has led initiatives to achieve carbon reduction strategies, waste reduction, adoption of current best practices and is active in cross council forums seeking improved industry standards in road surfacing.

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