While the main purpose of barriers is to provide safe environments, growing environmental concerns and the need for sustainable development has made the construction sector adopt systems and designs that can combine safety standards with sustainable solutions.
Green infrastructure centres on integrating nature based solutions, energy-efficient technologies, and sustainable design principles into the built environment.
This approach includes strategies such as using recycled materials, adopting renewable energy sources, and following green building standards. For example, barriers made from recycled materials or green infrastructure could realise a lower carbon footprint, improve air quality and reduce noise pollution, whilst providing safety for users in various settings.
Research from RMIT in Victoria shows vehicle emissions along mega-projects such as the North East Link, Monash Freeway and Eastern Freeway will exceed the state’s new air pollution standards by 2036, creating poor air quality in the surrounding areas. This has led to the launch of a research project which uses vertical gardens and green walls to improve noise and air pollution.
RMIT architect and sustainability lecturer Nadine Samaha says existing motorways use concrete and steel columns, which can reduce noise but make no impact on air quality – a particular problem for residents near major roads.
“Motorway air pollution can have a significant effect on the health of residents living nearby,” said Samaha. “Some 75 per cent of Melbourne’s air pollution is caused by vehicle emissions which carry harmful chemicals that can have devastating health impacts including cardiac arrest, low birthweight, asthma and reduced lung function in children.
“According to the Australian Institute of Health and Welfare, more than 3000 Australians die early from urban air pollution each year – more than the national road toll.” The project proposes to retrofit and transform Melbourne’s motorways by creating ecological buffers to address noise and air pollution, while improving liveability and protecting residents from urban heat island effects, notoriously affiliated with asphalted roads and concrete barriers.
The most common pollutants emitted by vehicles are carbon monoxide, carbon dioxide, nitrous oxide, ozone and particulate. These air pollutants also contribute to climate change.
To reduce air pollution on Melbourne motorways, the project integrates a combination of vertical greening, green walls and rain gardens to absorb some of the motorway’s vehicle emissions.
“A study conducted by the University of Surrey found just having trees besides roads is not enough to reduce air pollution,” Samaha said. “This is because the tree canopy is often too high to provide a barrier or filter for road-level tailpipe emissions.
“They found the most effective way for improving air quality, reducing pollution exposure and cutting back carbon by up to 63 per cent is to plant dense green infrastructure hedges or a combination with trees.”
According to project co-designer Dr Jordan Lacey from the RMIT School of Design and RMIT Urban Futures ECP, current methods of reducing motorway noise are focused on noise wall construction, however there is always residual noise that impacts on the wellbeing of residents.
“By integrating sound capturing systems of residual noise with microphones we can change the typical noise heard on highways into something more melodic,” he says. “This process, known as noise transformation, captures residual noise which is then fed back through a computer-based algorithm and played back through a speaker array to mix with environmental sounds.”
Another research team at the University of Melbourne has turned waste tyres into concrete road barriers, with the main aim to address the significant environmental problem of waste tyres in Australia.
According to the Victorian Waste Management Association, Australia generates over 56 million tyres eachyear, with 60 per cent of end-of-life tyres being disposed of improperly in landfills or through illegal dumping.
The team’s project involved the creation of a sustainable rubberised concrete mixture design for road barriers, collaborating with Tyre Stewardship Australia and Saferoads.
The road barrier mixture has a higher impact resistance compared to traditional concrete, and has significant benefits over existing road barriers including reduced severity of driver injuries and deaths on impact, longer life cycles for manufacturers of concrete barriers, and a lower carbon footprint.
The world’s first full-scale rubberised concrete barrier crash test was conducted in 2022, where 16 rubberised concrete road barriers were tested against a vehicle crashing at a speed of 100 km/hr. The test led to the approval for building and using the new rubberised concrete barriers in Australia.
Another industry initiative uses recycled plastic to manufacture new plastic barriers, with the goal of meeting the nation’s ambitions to reduce the amount of plastic waste. More than 10,000 barriers, equating to more than 500 tonnes of high-density polyethylene plastic, have been repurposed and which would have otherwise goneto landfill.
The use of recycled waste, sustainable materials and green infrastructure can also offer solutions for many other applications requiring safety, aesthetics and pollution reduction.
For example, in public spaces such as footbridges, greened fall protection systems could improve air quality and reduce noise, while maximising safety and reducing the risk of climbing.
Green façades can also act as a natural barrier which provides insulation, improves air quality, reduce noise pollution and enhances the aesthetics of a building.
In interior spaces, green barriers can also be used, with climbing plant systems providing both safety and a structure for indoor greenery to grow, improving air quality and health by absorbing indoor pollutants.
By adopting green infrastructure, sustainable construction materials, energy efficient designs, and integrating natural elements into urban spaces, the sector has the ability to make real change in the built environmentwhile still meeting building safety standards.