Sometimes you need indisputable proof to act upon even the clearest assumptions. If you’re a city council, spending public money on infrastructure to save local communities, this burden of proof is everything.
The idea the natural environment can be harnessed in urban infrastructure to manage climactic events and climate change is hardly novel. The concept of ‘green infrastructure’ – to help with flooding, heat, pollution, and soil quality – has been around for as long as urban farming and garden allotments, in the late 19th century.
But a smart city initiative in Chicago, in the US, has just published the results of an 18-month pilot to monitor and compare flood prevention measures, which show categorically the effectiveness of such infrastructure, which ranges from permeable pavement to landscaping elements like bioswales and planters.
In general, cities do not know the most effective ways to deploy and maintain these types of infrastructure, despite pumping public money in them. City Tech, born in 2015 from a merger between City Digital and the Smart Chicago Collaborative, has sought to make the business case definitive for civic authorities by shedding light on the effectiveness of each.
In Chicago, as in other cities around the globe, too much water in the city sewers will back up into basements, or lead to the release of sewer water into the river and other waterways.
Starting in late 2016, City Tech joined with the City of Chicago and Microsoft, as well as Los Angeles engineering firm AECOM and Massachusetts storm-water system provider Opti, to develop and deploy sensors at four green infrastructure locations around the city of Chicago.
The sites include porous asphalt and permeable pavers, in the Roseland and Chatham neighbourhoods on the city’s south side, a bioswale on Goose Island, and permeable pavers and infiltration planters in the Uptown district in the north of the city; each feature is designed to absorb water and delay its release into the city’s sewers.
The sensors collected micro-weather and soil moisture data, and sent it live to the Microsoft’s Azure IoT cloud. Since inception, data has been made available on the city’s open data portal. The pilot has tested the ability of the end-points to collect data and withstand their environments.
AECOM has reviewed a year’s worth of data and determined each structure’s effectiveness, defining success as a detectable and consistent increase in soil saturation during. Results have showed, categorically, green infrastructure reduces surges of water hitting the drainage system.
Bioswales and porous pavement is most effective at slowing the progress of water into city sewers, it found; the performance of green infrastructure is consistent, no matter the volume of rain. More than this, it found the cost of green infrastructure monitoring can be reduced through automated notification of when sensor maintenance is required; during the pilot, maintenance alerts were issued when equipment went offline.
Elizabeth Grossman, director of national partnerships and programmes in Microsoft’s cities team, says: “By harnessing cloud, data and mobile technologies, we can gather, share and analyse data in new ways that improve community safety, sustainability and quality of life.”
Bill Abolt, vice president of AECOM’s energy division, says: “Green infrastructure does more than manage flooding; it can make cities more liveable and resilient. The ability to track and verify the multiple benefits of green infrastructure is an important and exciting breakthrough nationally, and we are already looking for opportunities to incorporate the advanced monitoring into our projects.”
