Having long designed to ensure infrastructure in the built environment is fail-safe, engineers are now leaning toward the concept of fail-soft.
In Infrastructure Australia’s Resilience Principles document, there are several mentions of the fact that resilient infrastructure and communities are not just robust and fail-safe, but are also safe to fail.
At first, these terms seem contradictory. However, as engineers are increasingly realising they can’t design out risk completely, they’re developing solutions that allow for adaptation and fast recovery, broadening the definition of fail-safe.
“Different shocks and stresses have come to the fore,” Samantha Peart, Global Head of Sustainability for Hassell, said. “Previously, we’ve had a lot of focus on designing out risk, as opposed to adaptation. But now, adaptation is becoming more of a focus as science tells us the actions we’ve taken thus far are not mitigating the risks.
“What’s the difference between designing out risk and designing for adaptation? It’s rarely that black-and-white, but take flooding as an example – one approach builds barriers to keep water out; the other accepts its inevitability to a certain extent and asks how spaces can adapt, absorb and even benefit from it.”
An excellent example of such a build is what has become known as the Dream Drain in Brisbane’s Hanlon Park. Once a concrete stormwater channel creating a scar across a nondescript piece of land between residential areas, it is now a biodiverse, 600 m creek meandering its way through a revitalised public park.
Soon after the project’s completion, Alan Hoban, Bligh Tanner’s Director Civil & Water told create, “We think it might be the most significant creek naturalisation project in Australia.”
Rather than trying to move water away as quickly as possible, the new creek and park instead anticipates being flooded by ensuring the softer landscape can accommodate and recover without catastrophic damage.
“The area has a 30 km² urbanised catchment upstream of it,” Hoban said. “You don’t need much rain in that catchment to cause flash flooding through the site.”
“We had four decent-sized floods during construction … So we didn’t even get to completion before we had it tested thoroughly. An open construction site with quite a number of flood events was a challenge and a frustration.”
The fail-soft space – which community members now treasure for its greenery and cycleways, its biodiversity benefits including bird life, fish in the stream and hundreds of varieties of vegetation, and the fact that children now have a healthy place to play – has added immeasurable value to the area.
What Infrastructure Australia says
In the Resilience Principles paper, Infrastructure Australia describes safe-to-fail as meaning “anticipate(s) failures and designed strategically to ensure failure is contained and minimised”.
Infrastructure and buildings should be able to absorb events, it said. They should be “prepared and ready to respond”.
“Well-constructed and well-managed systems that lessen the impact of all hazards on communities and infrastructure services” epitomise resilience, the paper said. “Systems should: anticipate and proactively plan for future shocks and stresses, and provide services and infrastructure tailored to community needs and preferences, at reasonable cost.”
Along these lines, Brisbane’s Hanlon Park doesn’t just enable a new level of flood resilience. It also provides amenity for the community and an ecosystem in which nature can thrive.
Components of resilient projects, according to the report, include:
- Resist: Robust, fail safe and safe-to-fail
- Absorb: Prepared and ready to respond
- Accommodate: Spare capacity, variety and sufficient reserves
- Recover: Restoration and response
- Transform: Future focused, foresight and reflective
- Thrive: Integrated, flexible, innovative and inclusive
- Effective: Production of desired or intended result, place-based planning and engagement
- Timely: Accountability, transparency and promptness
Gardiners Creek Corridor: A grand plan
On a different scale to Hanlon Park, but with a similar vision, the City of Stonnington is progressing a renaturalisation master plan along almost nine kilometres of densely populated Melbourne.
“Gardiners Creek – Kooyongkoot is a significant waterway within Stonnington that provides an important biodiversity corridor, highly valued open space, is a key commuter route, delivers recreation hubs, Indigenous heritage and public transport links,” the City of Stonnington said.
The master plan, the council said, “is a unique opportunity for the City of Stonnington to set a new benchmark for waterway health, biodiversity initiatives and active transport and recreation infrastructure that will deliver positive long-lasting community outcomes.”
The catchment has been heavily affected by flooding, which itself has caused further infrastructure damage, the master plan said.
“The management of this over the past decades has been through concreting and canalisation of the creek at many locations along the water corridor and tributaries.
“A major contributing factor of creek flooding over the past decades has been the major reduction in the amount of permeable surfaces, such as grass and gardens. This is due to the increased development and paved surfaces throughout the catchment due to growth in population, density of living and urban development.”
The master plan concept is to create green infrastructure, including golf course redesign that acts as wetlands – a rainwater storage and harvesting system – reducing peak flooding, providing urban cooling, and adding to the amenity and biodiversity of the area.
The new way forward for resilient engineering
Resilience is not so much about fighting against the inevitable such as water, wind, fire and heat, but is instead about living with and recovering fast from these forces, and thriving in their wake.
Projects taking on such challenges, including Hanlon Park and Gardiners Creek, are increasingly proving that fail-soft, or safe-to-fail, solutions are not an admission of defeat, nor a second-rate option.
In fact, when executed well, safe-to-fail solutions in the built environment could prove to be the finest form of engineering – a true co-existence of the built environment, community and nature.
