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Under the Viaduct,

Neglected spaces no longer

A bridge can be a road but also a roof. An elevated rail line can be used to hang lighting and signage for a rain-protected bike path underneath. Unfortunately, such multi-faceted solutions aren’t all that common. All it takes is a 20-minute walk around downtown Sydney to see how rarely the room beneath viaducts are considered in design. At best, these spaces are left gloomy and idle. At worst, they become magnets for vandalism and crime.

But does this always have to be the case?

We don’t think so. And we’ve spent the last two years trying to prove it. Under the Viaduct is a multi-disciplinary research project that pulls together experts from ours structures, landscaping, urban planning and lighting teams to dream up better uses for these underpasses that run like scars across our cities. The research was funded by Arup University in Australasia and conducted between our offices in Melbourne, Sydney, London, Johannesburg and New York.  

Project Summary


2 years to complete the research

5Arup offices collaborated

7enquiry-by-design exercises conducted

Our recently published discussion paper, put together in partnership with the New South Wales Roads and Maritime Services (RMS), offers some suggestions on how we might inject social purpose into these once neglected corners of our cities.

Key to our research is an approach called enquiry-by-design. We began by scoping case studies, from Addis Ababa’s elevated Light Rail Train to the raised highway and highway junctions of The WestWay in London. We then held a number of workshops to explore what works and what doesn’t. The WestWay is a thriving example of how a viaduct undercroft can be reclaimed and filled with galleries, green spaces and cafes. In Addis Ababa, such opportunities have yet to be captured.

Learn more about our research into turning neglected spaces into useful places.

One of the keys to this is envisioning how these spaces can help to activate the adjacent areas in which they’re located. That might be through pedestrian and cycle networks, public realm improvements like art or lighting, or even how these spaces might be occupied by buildings – offices, artist studios or maybe even homes. ”

Matt Lally Matt Lally

Throughout these workshops we consulted with stakeholders to determine how certain outcomes had come about and how we might reimagine these spaces more creatively going forward. Can we infill the space beneath a rail line with a community garden? How about placing low-rent market stalls beneath the sheltered overhang of an elevated highway? We’ve presented a number of possible solutions, each matched to the most appropriate viaduct type (which we’ve categorised into one of four major typologies.)

Read our Under the Viaduct: Neglected spaces no longer report

How we activate existing viaduct spaces is important

But it’s also crucial that we begin to design these purposeful spaces into new infrastructure projects going forward. To consider this problem, we met with a number of key New South Wales (NSW) government departments over the duration of the project. 

We wanted to make sure we fully understood the design, procurement, management and maintenance processes behind major transport infrastructure projects in order to get a better understanding of technical, institution or policy challenges that currently exist. Effective solutions need to benefit everyone – from community to government to industry. We set out to create a set of practical recommendations that can satisfy all three. ”

Safiah Moore Senior Planner

The need for multi-purpose infrastructure is more pressing than ever.

Urbanisation is a global trend and land is becoming increasingly rare and expensive. Sydney is swelling at approximately a million people per decade. We need to insure that the hundreds of rails, roads and bridges being built as part of the NSW’s current transport infrastructure boom serve a social purpose beyond simply acting as a way to get from A to B?


Maximising the way we use urban space isn’t only efficient – it has the potential to make our communities safer and healthier. Removing graffiti from streets has been shown to reduce crime by as much as 30%. Providing communities with active transport options can boost their physical and mental wellbeing. While injecting green spaces into the neglected corners of our cities has been shown to increase civic pride, it has the added benefit of increasing biodiversity, mitigating floods and providing climate resilience.

The opportunities may be endless but imagination is the first step.