New research shows a scientific approach can optimize bike lane planning

University of Toronto, Rotman School of Management

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Sheng Liu is an Assistant Professor of Operations Management and Statistics at the University of Toronto's Rotman School of Management. His research interests lie in smart city operations (especially transport, last-mile logistics, and sustainable/climate-resilient infrastructure planning) and data-driven decision-making (the integration of predictive and prescriptive analytics). His research has been published in Management Science, Operations Research, Manufacturing & Service Operations Management, INFORMS Journal on Computing, and IEEE journals. He received a PhD in Operations Research from UC Berkeley in 2019, and a BSc in Industrial Engineering from Tsinghua University in 2014. He has contributed to the development of advanced decision-making tools for leading companies including Amazon, Lyft, JD.com, and CNPC.

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Credit: Rotman School of Management

Toronto – When it comes to opinions about bike lanes, few of us are stuck in neutral. Love them or hate them though, new research says a dose of scientific rationality can help locate them in the best places. Congestion is minimized while more people ditch the car in favour of emissions-free, two-wheeled commuting.

Working with two other academics, smart city researcher Sheng Liu pulled data and talked to city planners in Vancouver and Chicago to develop a model that can help municipalities choose optimal locations as they expand their cycling lane networks in response to growing demand.

“Our model provides a systematic decision-making tool for municipalities to design new bike lanes using existing data,” said Prof. Liu, an assistant professor of operations management and statistics at the University of Toronto’s Rotman School of Management. “It helps policymakers better quantify and evaluate the potential benefits and risks of bike lane construction. In particular, it can predict whether and where traffic will get better or worse and if emissions will go down.”

Bike lanes have taken off across North America, leading to reduced traffic fatalities, lower-cost access to private transportation and improved physical activity for cyclists. But, as many commuters have already concluded, “ignoring traffic dynamics when designing bike lanes can needlessly worsen congestion,” the researchers write. And there might not even be much of an uptick in cycling ridership.

Part of the problem is that city planners tend to rely on simplified planning approaches that can't account for all the factors that influence the impacts of locating a bicycle lane on a particular roadway, or multiple ones in a roadway system.

The researchers' model uses a city's traffic and commuter mobility data to predict how cycling and traffic congestion will behave and change according to where bicycle lanes are located. The model estimates how driving travel time changes according to vehicle volume and road features, the attractiveness of cycling or driving on a roadway according to predicted travel times and the presence of bike lanes and, based on all of that, plus a host of other variables, which roads in a network will have the most cycling use and least congestion if bike lanes are located there.

Applied to the city of Chicago, one of the most traffic-congested U.S. cities and where expansion of its cycling network is a major policy priority, the model estimated that adding 40 km of additional bicycle lanes in specific locations would increase cycling ridership from 3.6 per cent to 6.1 per cent in the city's downtown, while increasing driving time by no more than 9.4 per cent.

“As bike lanes expand, some roads may observe more congestion, and some roads may actually see improved traffic,” said Prof. Liu. “On the network level, we find that the overall travel time for all commuters is shorter under the proposed bike lane expansion plan. This implies lower emissions as well.”

Acknowledging that bike lanes can inspire heated debates, Prof. Liu advised that "we should let data speak and follow a scientific approach" to evaluate their effectiveness. "Simply taking out bike lanes from the streets would not solve our congestion problem and could likely make it worse."

The research was co-authored with Auyon Siddiq of the University of California, Los Angeles and Jingwei Zhang of Cornell University. It will appear in Management Science.

Bringing together high-impact faculty research and thought leadership on one searchable platform, the Rotman Insights Hub offers articles, podcasts, opinions, books and videos representing the latest in management thinking and providing insights into the key issues facing business and society. Visit www.rotman.utoronto.ca/insightshub.

The Rotman School of Management is part of the University of Toronto, a global centre of research and teaching excellence at the heart of Canada’s commercial capital. Rotman is a catalyst for transformative learning, insights and public engagement, bringing together diverse views and initiatives around a defining purpose: to create value for business and society. For more information, visit www.rotman.utoronto.ca

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Journal

Management Science

DOI

10.1287/mnsc.2022.00775 

Method of Research

Observational study

Subject of Research

People

Article Title

Planning Bike Lanes with Data: Ridership, Congestion, and Path Selection

 

Former NIJ director proposes new framework to enhance rigor, impact of criminal justice intervention evaluations

Approach can guide policymaking and program investments, yield more credible findings

Crime and Justice Research Alliance

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Experimental research is fundamental to criminology, but reaching consensus on rigorous evidence and using that evidence to determine what works remains an ongoing challenge to the field. In a new article, the former director of the National Institute of Justice (NIJ) within the U.S. Department of Justice’s Office of Justice programs, proposes a framework to situate both the role of rigorous evaluation and its results in a more robust understanding of the effectiveness of social programs. According to her new framework, the more deliberate the implementation of a social program, the more likely it will yield its intended impact.

“Deliberate implementation can enhance our understanding of what constitutes an effective intervention and what factors explain each outcome,” says Nancy La Vigne, a criminologist who previously directed the NIJ and authored the article, which is published in the Journal of Experimental Criminology. La Vigne is an expert whose work is promoted by the NCJA Crime and Justice Research Alliance, which is funded by the National Criminal Justice Association.

“This information is essential in guiding policymaking and program investments by government agencies and philanthropy,” adds La Vigne. “It yields more credible findings for decision makers, boosts the likelihood of successful replication, and helps bridge the evidence-to-action divide.”

The impetus for the current debate in criminology over the role of rigorous evaluation is a 2023 article by researcher Megan Stevenson in the Boston University Law Review. Stevenson argued that rigorous evaluations, which she defines solely as randomized controlled trials (RCTs), frequently yield null results and that interventions previously found to be effective often fail to replicate. Stevenson suggested that the null results are because the criminal justice system requires systemic changes, which are unable to be captured by RCTs. Reaction by the criminology community fueled a robust debate over the role, definition, and value of rigorous research in public forums.

In her article, La Vigne notes that absent from the debate was any recognition of the importance of researchers and programmatic partners having a shared understanding of the local context and quality of criminal justice interventions. She introduces the Titanium Law of Evaluation, which emphasizes the importance of deliberate implementation, as defined by adherence to model fidelity and application to local context, elements that are often inadequately addressed in evaluations of criminal justice interventions.

La Vigne advocates for using an ongoing feedback loop, based on psychologist Kurt Lewin’s Action Research Model, in which researchers routinely share findings about opportunities to improve implementation fidelity that are often necessitated by local contexts and other factors. Sharing this information during the evaluation enables program implementers to make midcourse corrections to improve the robustness of the intervention and its likelihood of yielding desired impacts.

She uses two case studies—one of the Honest Opportunity Probation with Enforcement program in Hawaii, designed to implement swift and certain sanctions for people on probation who have substance use disorders, and the other of Center for Employment Opportunities, one of the largest employment programs for people re-entering society after incarceration in the United States—to illustrate the importance of measuring implementation fidelity, making mid-course corrections, and adapting programs to local contexts to foster desired outcomes.

La Vigne concludes that the Titanium Law emphasizes the need for a nuanced understanding of implementation processes, promoting collaborative evaluations that consider both fidelity and local context—both key components of implementation science. She recommends integrating these principles into criminology curricula and fostering partnerships between researchers and practitioners to improve evaluation outcomes.

“The Titanium Law of Evaluation elevates a vital but often overlooked component of current evaluation practice: focusing on adapting program components to local contexts and ensuring implementation fidelity, rather than focusing solely on the theory that underlies an intervention,” explains La Vigne. “By doing so, adherence to the Titanium Law can promote both successful implementation as well as successful replication in different settings, all in the interests of public safety.”

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Journal

Journal of Experimental Criminology

DOI

10.1007/s11292-024-09650-9 

Article Title

The Titanium Law of Evaluation: Increasing the impact and replicability of safety and justice interventions through deliberate implementation and adaptation

 SPAGYRIC HERBALISM

This research is absolutely nuts – for better health care

A University of Chicago Pritzker Molecular Engineering PhD student has created a new material from tree nuts with a broad number of medical applications that benefit patients

University of Chicago

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University of Chicago Pritzker School of Molecular Engineering PhD candidate Changxu Sun holds up a small malva nut and a submerged one to demonstrate how much it swells in water. Sun is harnessing this “natural hydrogel” to create new medical devices.

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Credit: University of Chicago / Chuanwang Yang

A nut used in herbal tea has become a hydrogel perfect for a variety of biomedical uses in new research from the University of Chicago Pritzker School of Engineering (UChicago PME) and UChicago Chemistry Department.

A paper published today in Matter created a malva nut hydrogel for medical uses ranging from wound care to ECG readings. The research doesn’t rely on the rumored health benefits of the nuts – in China, they’re known as the sore throat remedy Pangdahai (PDH) – but for their ability to swell in water.

“You never saw the fruit from a tree expand in that kind of volume,” said first author Changxu Sun, a UChicago PME PhD student.

Where others saw gooey tea residue, Sun saw possibility.

“It is a remarkable discovery from a remarkable student,” said Sun’s principal investigator, University of Chicago Chemistry Prof. Bozhi Tian. “Changxu looked at herbal tea and saw a world of sustainable biomedical applications ready to be built.”

From tea...

In traditional Chinese medicine, malva nuts are known as Pangdahai, often used in tea as a sore throat remedy, similar to adding ginger or lemon. A sniffling person pops the small, dried nut in hot water and watches the magic unfold.

“Originally, it’s an oval shape one centimeter in width. Once you soak it in the water, it will expand about eight times in volume and 20 times by weight, turning into a gelatinous mass, like a jelly,” Sun said. “After you drink the beverage, you’re left the jelly as a waste. People usually throw that out.”

For comparison, rice swells by about three times by weight when cooked. Chia seeds swell to 10 times their weight when added to water; the snow fungus used in many Asian soups has a similar rate.

But the malva nuts’ 20-fold increase leaves them all behind. Sun and Tian saw potential in the gelatinous food waste thrown out with yesterday’s tea.

“We said, ‘Okay, that's a natural hydrogel,’” Sun said.

... to hydrogel

Hydrogels are gooey water-based substances noted for their many applications in health care. As soft and water-loving as human tissue itself, hydrogels are used in wound care, fighting infection and spurring healing beyond what a bandage can do. They’re used in drug delivery systems, implantable bioelectronics like pacemakers, tissue repair, ECG and EKG readings, and other uses.

Turning nuts into medical devices takes more work than just popping them in tea.

First, the nuts are crushed in a blender and then run through a centrifuge to extract as much of the soft, expanding polysaccharide hydrocolloid as possible while getting rid of the hard structural lignins that give nuts their shells.

They then freeze-dry the hydrocolloid solution, removing all the water to create a dry scaffolding of pure malva nut polysaccharide. Picture a dried-out kitchen sponge popping back into shape under the kitchen tap.

“If we hydrate those scaffolds again, that becomes a gel,” Sun said.

The team began testing their malva nut hydrogel in a variety of medical uses, from wound care to biomonitoring.

“We found it demonstrated superior performance and qualities compared to commercial ECG patches. And then we also applied to the tissue surface in vivo, demonstrating great recording of biosignals,” Sun said. “We wanted to show people should shift their attention into the unexplored properties and unexplored resources of natural plants.”

Sun hopes the new, naturally derived hydrogel will provide a new source of powerful but less-expensive medical resources across the globe, but particularly in the Southeast Asian nations where the malva tree grows.

“They’re low-income countries. Their healthcare systems are always limited by this lack of resources,” Sun said. “Here we have a local, native material that can be used to create valuable healthcare solutions while providing these impoverished areas some economic stability.”

That doesn’t sound nuts at all.

Citation: “Sustainable Conversion of Husk into Viscoelastic Hydrogels for Value-Added Biomedical Applications,” Sun et al, Matter, February 17, 2025. DOI: 10.1016/j.matt.2025.102002.

Malva nuts, known in Chinese as the sore throat remedy Pangdahai, expand about eight times in volume and 20 times by weight in water. For comparison, rice swells by about three times by weight when cooked and chia seeds swell to 10 times their weight.

Credit

University of Chicago / Chuanwang Yang

Journal

Matter

DOI

10.1016/j.matt.2025.102002 

Article Title

Sustainable Conversion of Husk into Viscoelastic Hydrogels for Value-Added Biomedical Applications

Article Publication Date

17-Feb-2025

 

Wildfires in the Andes cause severe soil degradation and hinder ecosystem recovery

A new study reveals the extreme vulnerability to wildfires of one of the planet's most arid regions: the Arequipa shrublands of Pichu Pichu, in the Andean Mountain range of Peru.

Universidad Miguel Hernandez de Elche

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Polylepis forest (dark vegetation) in the area affected by the Pichu Pichu wildfire in September 2018.

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Credit: Jorge Mataix Solera.

In September 2018, a wildfire burned nearly two thousand hectares of shrubland on the Pichu Pichu volcano, an ecologically significant area in the Peruvian Andes. Unlike Mediterranean ecosystems, where vegetation has evolved strategies to withstand fire, the volcanic soils of Arequipa—one of the driest regions in the world—are not adapted to wildfire disturbances. A Miguel Hernández University of Elche (UMH) research team collected and analyzed soil samples from the burned area at 3,700 meters above sea level to understand how these fragile ecosystems respond to fire disturbances.

The results, published in the Spanish Journal of Soil Science, indicate that four years after the fire, vegetation and soil combustion, combined with post-fire erosion, have caused a severe loss of soil organic carbon (SOC)—a key element for soil fertility. “The Peruvian Andes are not prepared for wildfires,” warns UMH professor Jorge Mataix Solera, a scientist with more than thirty years of experience studying post-fire soil recovery. Mataix emphasizes that fire is a natural ecological force, but its effects vary significantly depending on the ecosystem. The study’s findings indicate that Pichu Pichu’s soil has undergone significant physical and chemical degradation after the fire, hindering ecosystem recovery. Furthermore, post-fire erosion has triggered additional degradation, reduced clay content, and weakened soil structure.

Post-Fire Water Repellency and Soil Vulnerability

One of the challenges identified in these arid soils is their natural tendency to repel water, a phenomenon influenced by organic matter characteristics and high sand content. This water repellency persisted after the fire, exacerbating erosion. Without vegetation to retain moisture, water runs off the surface rather than infiltrating the soil, accelerating erosion. “While well-structured and evolved soils, such as Mediterranean soils, have a high water-holding capacity, young volcanic Andean soils, which are naturally sandy, lose this ability after fire-induced organic matter loss,” explains UMH researcher Minerva García Carmona.

“This is why understanding the effects of fire on these young and fragile soils is crucial,” García adds, “especially considering the role of plants, which form the combustible material in wildfires and influence soil degradation.”

Key Plant Species and Their Influence on Post-Fire Soil Degradation

The study focused on two native plant species with a critical role in the ecosystem: Berberis lutea, known as "palo amarillo del Perú," and Parastrephia quadrangularis, or "tola." Researchers examined whether fire had different effects on soils depending on the dominant vegetation. The results revealed that areas dominated by Berberis lutea experienced greater soil degradation. “This is likely because it is a larger plant with higher biomass, which intensified combustion effects,” García clarifies.

The UMH research team has extensive experience studying wildfire impacts on Mediterranean forests, which have developed resilience strategies due to their long history of fire exposure. However, their findings in Pichu Pichu confirm that volcanic soils in Arequipa naturally retain less water and are particularly vulnerable to fire degradation. This highlights the increasing threat wildfires pose to these ecosystems.

A Fragile Ecosystem in the Andean Volcanic Belt

Pichu Pichu is located in the central volcanic zone of the Andes. UMH researchers collected soil samples at approximately 3,700 meters above sea level, where annual precipitation averages just 385 mm, concentrated over three to four months. This makes the Arequipa region a "cold desert," with temperatures ranging from 4 to 18°C. The vegetation consists mainly of highly drought-adapted shrubland.

Due to limited precipitation, the Andean Volcanic Belt is a crucial water source for surrounding areas. “Although Pichu Pichu is dominated by shrubland, its foothills support forests that host a rich diversity of plant and animal species,” explains a UMH professor. These foothills include queñua forests (Polylepis), whose endemic species in Peru are currently endangered.

The Rise of Wildfires in Peru and Climate Change Implications

In Peru, most wildfires occur between July and October. In September 2024, the satellite monitoring project Queimadas recorded an all-time high of 7,037 wildfire hotspots in the country. “In a region like Arequipa, located in a desert environment, understanding soil response under new fire regimes is essential for assessing ecosystem resilience to climate change,” explains a UMH researcher.

Mataix believes that the more we learn, the better we can help design prevention strategies and post-fire treatments to mitigate the effects of rising temperatures and intensified droughts. “This is as crucial in Peru as it is in Spain or California,” Mataix concludes. “Although fire is a natural phenomenon, the climate crisis is exacerbating these events, and we must do everything possible to restore and protect these ecosystems.”

Burned Berberis lutea after the Pichu Pichu wildfire in September 2018.

Credit

Jorge Mataix Solera.

Berberis lutea on the Pichu Pichu volcano (Arequipa, Peru).

Credit

Tatiana Salazar.

Parastrephia quadrangularis on the Pichu Pichu volcano (Arequipa, Peru).

Credit

Lunsden Coaguila.

Shrubland landscape on the Pichu Pichu volcano (Arequipa, Peru).

Credit

Jorge Mataix Solera.

First centimeters of loamy sand soil sampled on the Pichu Pichu volcano (Arequipa, Peru).

Credit

Jorge Mataix Solera

Journal

Spanish Journal of Soil Science

DOI

10.3389/sjss.2025.13983 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Soil Degradation Evidence Following a Wildfire in Arequipa’s Andean Region, Peru