Cities & sustainability IV 2026-

Concrete with a human touch: Can we make infrastructure that repairs itself?
Mouna Reda, Post doctorate fellow, Department of Civil Engineering, McMaster University;
Samir Chidiac,Professor, Civil Engineering, McMaster University
(The Conversation) As winter approaches, Canada’s roads, bridges, sidewalks and buildings are facing a familiar problem: cracks caused by large temperature swings. These cracks weaken infrastructure and cost millions to repair every year.
But what if concrete could heal itself like human skin, keeping our structures, roads and bridges strong and saving millions of dollars?
Concrete is made by mixing cement, water, aggregate and other chemicals used to enhance its properties. As cement reacts with water, it forms a paste that binds everything together.
During this process, changes in volume, improper placement and finishing, and later environmental factors can create cracks. These cracks allow water, other liquids, gases and harmful chemicals to penetrate the concrete, compromising its strength over time.
This challenge has led researchers to eagerly explore what can be done to heal these cracks. In our research, we are researching how self-healing concrete can make infrastructure more durable.
Self-healing concrete
Traditional concrete is able to mend small cracks when water triggers leftover cement in a process known as autogenous healing. This process, however, is very slow and limited to narrow cracks. Since concrete is man-made, it has limited ability to “self-heal” without a little extra help. This led researchers to develop what is called autonomous healing. 8 December 2025
Lessons From the Rise and Fall of the Pedestrian Mall
Car-free shopping streets swept many U.S. cities in the 1960s and ’70s, but few examples survived. Those that did could be models for today’s “open streets.”
(Bloomberg) The pedestrian mall landscape is far different today than it was for cities in the 1970s. While pandemic-related fears of social gatherings and the decline of brick-and mortar-retail present new challenges, most U.S. cities today are no longer hemorrhaging residents to the suburbs, and a decades-long urban crime decline — notwithstanding a recent violence uptick some cities have seen — has helped ease the kinds of public safety fears that doomed so many of the first generation of pedestrian malls. Many downtowns and central business districts now have more full-time residents than they did in decades past, a density boost that bodes well for this new wave of shared streets. Officials must weigh many factors as they bring their urban centers back to “normal,” but they should remember that, for many, normal means experiencing the city via a car-free public space. 9 September 2021

28 April
Highlights from Bloomberg CityLab 2026 in Madrid
Madrid’s balancing act
“There’s a word that defines the future of the city, and that allows us to guarantee our growth, which is balance — balance in the ability to attract and retain talent … and at the same time to know that if we lose our identity, then we will lose our soul.”
José Luis Martínez-Almeida, Mayor of Madrid
As we reported this week, the Spanish capital is walking a fine line as it attracts luxury tourism while trying to retain the longtime laid-back culture that makes the city special. On Tuesday, the mayor echoed the sentiment of people quoted in our story: that the city risks losing its soul.
Aging in place – 86 years
Madrid has the longest life expectancy in the European Union, according to José Fernández, a member of Madrid’s city council and a leader of local efforts to support policies for healthy aging.
Getting ahead of the AI boom
“We don’t want to move fast and break things. We want to move fast and make things without leaving anyone behind.”
Sadiq Khan, Mayor of London
Kahn said the city is already using AI to predict congestion, deal with poor housing conditions and speed up cancer diagnoses. Now, he’s looking to ensure residents have the skills to use the technology safely, while preparing for potential disruption of the job market.
Eliminating blight, block by block
11,851 The number of vacant properties in Baltimore, Maryland, as of April 2026, down from 15,672 in December 2020 — a reduction of nearly 25%, according to Mayor Brandon Scott. He credited the reduction to a community-facing program aimed at tearing down or renovating empty homes and beautifying blocks.

8 April
Editor’s note: This is the second publication in a three-part series that seeks to provide local leaders across the public, private, and civic sectors with tools to advance inclusive downtown recovery in small and mid-sized regions.
Tackling the paradox of underutilized land in small and mid-sized city downtowns
Tracy Hadden Loh, Hanna Love, and Bethany Krupick
(Brookings) You can’t make more land. Even after generations of infrastructure expenditures aimed at overcoming this limitation via highways, commuter rail, and streetcars, downtown land in places large and small remains disproportionately valuable due to regional accessibility and concentration of legacy assets.
Yet many American downtowns and Main Streets are plagued by a paradox: Land and buildings sit underutilized or vacant next to some of the most expensive real estate in their regions. This report attempts to explain that paradox and identify actionable and inclusive recommendations for resolution through on-the-ground research insights from four American small and mid-sized cities (SMCs)—Akron, Ohio; Birmingham, Ala.; Cincinnati; and Richmond, Va.—that are actively working to advance equitable downtown revitalization in a time of uncertainty and change.
30 July 2025
Editor’s note: This report is the first in a three-part series seeking to fill this gap by surfacing insights from downtown recovery efforts in four small and mid-sized cities:
Small and midsized downtown recovery: Overcoming obstacles and uplifting innovative solutions in four regions
Tracy Hadden Loh and Hanna Love
Over the last five years, many have fretted about the risk of America’s largest downtowns falling into a “urban doom loop,”predicting that pandemic-era declines in office work, retail activity, and tax revenue would inevitably prompt a fiscal death spiral for municipalities. These concerns are only now beginning to subside for some of the nation’s largest “superstar cities” due to promising rebounds in downtown residential activity, weekend foot traffic, and tourism.
Yet the national media has given less attention to the recovery trajectory of small and midsized city (SMC) downtowns,1 even though 1 in 4 Americans live in these cities. Many of these downtowns have a long history of confronting challenges that mirror—but precede—the pandemic-era “doom loop,” including population decline, high concentrations of vacant buildings, and precarious fiscal health.

23 March
How port cities like Singapore shaped the world
(CBC Ideas) Port cities are where worlds collide. They are a place of cultural, economic, political and religious contact. They’ve existed for millennia and facilitated the birth of empires and the rise of a globalized economy. Without port cities, our world would look very different. In the first episode of our series on how port cities shaped the world as we know it, UBC journalism professor Kamal Al-Solaylee visits Singapore — a constantly-evolving port city whose maritime roots go back to the 13th century.

9 February
Antarctica’s newest research station holds a lesson for snowy cities
The Discovery Building features a wind deflector that prevents snow from piling up next to the building. It could change how we build in harsh climates.
(Fast Company) Perched on the southern edge of Adelaide, an island on the Antarctica Peninsula, the Discovery Building spans two stories and nearly 50,000 square feet. It is clad in highly insulated metal composite panels and topped with a mono-pitch roof that slopes in just one direction, so snow slides right off instead of piling up.
Most notably: it sports an innovative feature called a wind deflector, which protrudes on the leeward edge of the building (the one sheltered from the prevailing wind) and prevents snow from piling up right next to the building. So far, the system has most commonly been used above doors to clear snow that would otherwise fall adjacent to the building, but the architects say it’s never been used at this scale before. The feature could change the way we design buildings for harsh climates.
The Discovery Building was designed by British firm Hugh Broughton Architects, which, over the past decade, has a gained a reputation for designing buildings that exist in extreme conditions. In 2013, the firm completed Halley VI, a raised building that sits on a floating ice shelf. Mounted on hydraulic legs with retractable skis, the station was specifically designed to be relocated if the ice shelf showed signs of breaking off, which it did in 2017. The entire base was successfully moved 14 miles inland.

5 February
Milan Olympics Housing Is Built for Easy Reuse
New athlete accommodations for this year’s winter games will convert to student dorms, helping to cut emissions.
Takeaways by Bloomberg AI
Milan’s new athletes’ village, designed by architects Skidmore, Owings and Merrill, was built to meet a discrete need after the games have ended: addressing the city’s shortage of student housing.
The village takes a significant step forward in sustainability, with features such as greener processes, photovoltaic panels, and prefabricated buildings, and its units can be easily repurposed for student housing.
The complex will increase the city’s student housing capacity by 6%, but locals are concerned that the prices, ranging from €592 to €1,065 per month, will make it unaffordable for many students and contradict the city’s goal of providing more affordable housing.

14 January
How street vendors and waste pickers can help cities manage growth
Gisèle Yasmeen, JW McConnell Professor of Practice, Max Bell School of Public Policy; Julian Tayarah and Umme Salma Master’s Students, Public Policy, McGill University
(The Conversation) The Milan Urban Food Policy Pact recently renewed global commitments to sustainable and equitable urban food systems. The pact has been signed by 330 cities around the world that have pledged to improve food production and distribution and to reduce waste.
Cities are now home to 45 per cent of the world’s 8.2 billion people, and that figure is expected to rise to 68 per cent by 2050. As they grow, cities are becoming key to shaping a sustainable future. Across the world, urbanization affects how food is grown, distributed and consumed, and cities are primary drivers of change in food systems.
As the Committee on World Food Security reaffirmed in October 2025, without intentional policy, this growth will not fuel the needed transformation to keep food systems sustainable.
Street foods and vendors are an essential component of the urban foodscape, providing affordable nutrition and critical income for many city residents. However, vendors are frequently met with hostility from municipal authorities who cite traffic and public health concerns.
In addition, at least one-third of food produced globally spoils, ending up in landfills, and wasting valuable resources, energy and labour. Urban waste pickers can play a vital role in reducing waste.
In many cities, waste pickers collect, sort and sell discarded materials like plastic, metal and paper for recycling or reuse. While waste pickers are more common in the cities of low and middle-income countries, they are also a feature of urban areas in wealthy countries.
… A 2020 study estimated that nearly 60 per cent of all plastic collected for recycling was undertaken by informal waste pickers.
Much of this plastic is related to food and beverage packaging discarded in urban areas. The United Nations Environment Program recommends that the estimated 20 million waste pickers around the world become an integral part of municipal waste management.

2025

23 December
Reducing household waste poses serious challenges in residential high-rises
Lisa Kowalchuk, Associate Professor of Sociology, University of Guelph
(The Conversation) Like much of the western world, Canada is facing a crisis in waste disposal as landfills reach their capacity. In Ontario, a live countdown gives municipal landfills just eight more years before they are full. We urgently need to reduce our garbage.
The scramble for a solution has governments considering and even approving questionable alternatives like incineration and opening new or dormant landfills in rural areas.
Colleagues and I conducted a study between 2022 and 2024 with a non-profit service provider called the St. James Town Community Corner in Toronto, and found an overlooked opportunity for greater waste diversion among renters in multi-residential buildings.
Our research team included Trisha Einmann, a PhD candidate in sociology at the University of Guelph, Alaa Mohamed, a client engagement worker with The Neighbourhood Organization and Aravind Joseph, a former co-ordinator with The Neighbourhood Organization.
St.James Town is a vibrant, densely populated neighbourhood with a high proportion of immigrants, racialized people and those with lower-than-average household incomes. At its core are 19 rental towers of 14 to 30 storeys that house about 18,500 people.
Policymakers must bring multi-residential buildings fully into the effort to divert household waste from landfill, so that communities like St. James Town can be part of the solution.