Green track will help filter rainfall and reduce flooding, among other benefits.
Planting vegetation along light rail tracks could be a great way to add huge amounts of green space to urban areas with relatively low cost and effort.
Research from Western Sydney University in Australia has revealed that the equivalent of two football fields’ worth of green space could be added to the middle of Parramatta — a large regional hub in the west of Sydney in New South Wales (NSW), Australia.
In a viability study commissioned by Transport for NSW — the state’s public transport body — Western Sydney University researchers found that installing what will be Australia’s longest green track will have multiple benefits.
After receiving the team’s report, Transport for NSW constructed three separate sections of green track totalling 1.3 kilometres, as part of the Parramatta Light Rail project, which is expected to open in 2023. Lead researcher Sebastian Pfautsch, an associate professor from Western Sydney University’s School of Social Sciences, says that replacing hard surfaces such as concrete and bitumen with grasses and groundcover offered a rare opportunity to green Parramatta city, where land is in high demand.
“If you put it together, we are adding more than one hectare of green space in downtown Parramatta,” says Pfautsch. “It’s amazing.”
The team’s review of green track around the world found that it can make cities cooler, quieter and improve their air quality, which would be particularly beneficial around areas such as Cumberland Hospital in Westmead, a neighbouring suburb in western Sydney. They also found that greenery along light rail tracks not only provides habitat and biodiversity, it filters and reduces stormwater runoff.
The team’s report notes that in Parramatta, where annual rainfall is 960 millimetres, between 480–670 litres of stormwater would be retained yearly for each square metre of green track. Any runoff would be filtered by the vegetation and contain fewer pollutants than if it had fallen on hard surfaces such as concrete.
Workers laying green track in Parramatta.
Pfautsch says green tracks increase property values and the viability of businesses along the tracks, such as cafes, as they create pleasant streetscapes. The Parramatta Light Rail program director Anand Thomas adds that the “green track will make the light rail blend in better with the existing local landscapes”.
While green track is found all over the world, it has never been tried in a hot, dry climate like that of western Sydney. Pfautsch’s review found that green track is suitable in western Sydney if appropriate plant species are used. “We proposed ground covers which had low mowing, nutrient, and watering requirements,” says Vanessa Howe, a PhD student and co-author of the report. “The species are native to western Sydney and are pretty tolerant to being walked over,” she adds.
The team also identified the need for proper irrigation and maintenance. As temperatures in Parramatta may regularly reach the high 40 degrees Celsius in the next five to ten years, irrigation will be essential. “Without regular maintenance it will look ugly and people won’t like it,” says Pfautsch. He is confident that the Parramatta green track will become a model for the rest of Australia.
“The positives are so overwhelming and the risks are manageable once you have the right strategies. Green track is a good example for progressive, functional urban design,” says Pfautsch.
The team’s report — together with the first section of green track, based on Australian native species, Zoysia macrantha ‘Nara’ turf, which was laid in February 2022 — was extremely well received. It won two Australian Institute of Landscape Architects (AILA) NSW Awards for research communication and infrastructure as well as the 2022 AILA National Landscape Architecture Award for Infrastructure.
“Transport NSW has since broadened some sections of the green track by lining the track bed with shrubs and trees. This maximizes the surface area that can absorb stormwater, which can then be used by the shrubs and trees for transpiration cooling,” adds Pfautsch. “It’s very good green infrastructure design.”