Dynamic Balance Evaluation of Urban Public Safety and Smart Sustainable Development —Based on the Entropy Three Parallel Two-Stage Dynamic DDF Model

Cities are often imagined as engines of progress, where smart technology and green design promise a future of efficiency and comfort. Yet, beneath the sleek interfaces of digital apps and the promise of sustainable growth lies a more fundamental reality: a city cannot function if its basic life-support systems fail. Before a city can be "smart" or "sustainable," it must first be safe. This means ensuring that the roads hold up, the water flows cleanly, and the food supply remains secure. When these foundational pillars crack, the advanced layers of urban life—whether they are high-speed data networks or carbon-neutral initiatives—can collapse instantly. The challenge for modern urban planners is not just to build these systems, but to balance the constant push for development with the equally urgent need for safety, ensuring that one does not undermine the other.

A team of researchers from Fujian Normal University in China set out to measure exactly how well cities are managing this delicate balance. They focused on thirty provincial regions across China, examining the years from 2017 to 2023. Their goal was to see if the drive to build "smart sustainable cities"—places that use technology to improve life while protecting the environment—was happening in harmony with the work of keeping people safe. To do this, they looked at two main areas. The first was public safety, which they broke down into three critical lifelines: the safety of infrastructure like roads and bridges, the safety of water systems, and the safety of the food supply. The second area was the city's overall smart and sustainable development, which they measured by looking at social well-being, economic health, environmental quality, cultural life, and the daily habits of residents.

The researchers used a sophisticated method to weigh these factors together, treating safety as the foundation that supports development. They found that, overall, most of the regions studied have not yet achieved a true balance between keeping people safe and moving toward a smart, sustainable future. Instead of a steady, even progress, the data showed a pattern where regions with lower efficiency tended to cluster together, while the few high-performing regions were scattered and isolated. The study revealed that the relationship between safety and development is not static; it changes over time. Between 2017 and 2021, the balance improved, but then it took a sharp turn for the worse. The researchers identified 2021 as a turning point. After this year, the overall level of balance declined significantly. This drop appears to be the result of a "perfect storm" of events, including the lingering economic and social effects of the pandemic and severe climate events like extreme heat and drought in 2022, which strained resources and forced cities to choose between immediate safety fixes and long-term development goals.

Perhaps the most revealing finding was how different types of safety affected the city's progress. The researchers discovered that food safety was the biggest bottleneck. In many places, the systems for ensuring food is safe and available were the weakest link, holding back the entire city's ability to become smarter and more sustainable. When a city struggles with food safety, it often has to spend its energy and money on fixing problems after they happen, rather than investing in the future. Water safety showed a different pattern; it acted like a threshold. Having enough safe water is a basic requirement, but simply meeting that minimum standard did not automatically lead to better smart development. It was necessary, but not enough on its own. Meanwhile, infrastructure safety, such as the condition of roads and public transport, showed that having safe infrastructure did not guarantee a smart city. Some regions had excellent roads and transport systems but still lagged in their digital and sustainable transformation, suggesting that physical safety and digital progress do not always move forward together.

The study also highlighted a troubling trend in how cities react to crises. When a major shock occurred, such as a natural disaster or a pandemic, resources were often pulled away from long-term smart development to address immediate safety threats. This created a seesaw effect: when safety governance went up, smart development often went down, and vice versa. The researchers observed that cities were not yet learning to integrate safety into their development plans from the start. Instead, they were treating safety as a separate, reactive task. The authors suggest that for cities to truly thrive, they need to stop treating safety and development as separate goals. They propose a new approach where safety is woven into the entire lifecycle of a city, from the initial planning of a building to the daily management of its water and food systems. By shifting from fixing problems after they occur to preventing them before they start, cities can build a foundation that supports both immediate safety and long-term, smart growth. The path forward, according to the study, lies in recognizing that safety is not just a barrier to development, but the very ground upon which a sustainable future must be built.