Snowstorms Reshape Sapporo: Study Maps Urban Mobility Under Extreme Weather

A study published by Muroran Institute of Technology researchers shows how Sapporo’s 2022 snowstorms fractured the city’s mobility into small, localized clusters, shrinking large networks and exposing the risks of its monocentric design. The findings highlight the need for clearer warnings, resilient infrastructure, and disaster planning that reflects real mobility patterns.

A new study by researchers at the Division of Sustainable and Environmental Engineering, Muroran Institute of Technology, explores how Sapporo’s urban mobility network responded to extreme weather. Led by Tran Vinh Ha and Mikiharu Arimura, the team analyzed mobile spatial statistics data provided by NTT Docomo to trace millions of trips before, during, and after the city’s historic snowstorms in February 2022. Their findings reveal how severe snowfall fractured Sapporo’s mobility into localized clusters, shrinking large networks into small islands of movement, while exposing the vulnerabilities of a city designed around a single central hub.

Tracking a City Through Data

Unlike earlier mobility studies focused on individual trips or average travel distances, this research treated Sapporo as a dynamic network. Districts became nodes, trips formed links, and communities appeared where movements converged. Using the Infomap algorithm, the researchers identified clusters of travel and revealed how they changed under normal and adverse weather. On weekdays, the city was dominated by a handful of large communities tied to work and school. Weekends and holidays splintered into dozens of smaller groups, reflecting leisure trips to parks, malls, and entertainment zones. When snowstorms struck, the number of communities increased, but their size diminished sharply as residents curtailed long-distance travel. At the peak of the first storm, the city’s largest community lost nearly half its size, a striking sign of fragmentation.

First Storm Hits Hard, Second Shows Adaptation

The two storms unfolded between February 6–7 and February 21–23, 2022. The first blizzard had the more severe effect, compressing travel into compact clusters and drastically shrinking the network. By the second storm, however, the disruption was less pronounced. The researchers suggest this was partly due to adaptation: road authorities were quicker with snow removal, commuters avoided peak snowfall periods, and awareness of risks was higher. Despite this resilience, mobility still shrank compared to normal conditions, with weekdays becoming more compact and weekend leisure trips scaled back. The contrast between the two events shows how cities can learn to cope, but also how the initial impact of extreme weather reveals their greatest weaknesses.

The Fragile Heart of a Monocentric City

Mapping the disrupted networks highlighted which places carried disproportionate weight. On weekdays, Sapporo Station, the government district, and Susukino entertainment area served as vital arteries. On weekends, commercial hubs such as Aeon Mall or university campuses became central in smaller networks. During storms, these hubs turned into bottlenecks: their closure risked collapsing entire subnetworks. Critical links were usually radial roads connecting outer districts to the center, and their obstruction left the monocentric design dangerously exposed. Unlike polycentric cities that spread activity across multiple hubs, Sapporo’s single core made it efficient in good weather but fragile in blizzards.

Warnings Ignored, Economic Ripples Felt

One striking discovery was the limited effect of official warnings. The Sapporo District Meteorological Observatory issued advisories and even severe alerts predicting poor visibility and traffic disruption. Yet mobility levels stayed high. Researchers believe vague language such as “exercise caution,” lacks the force of explicit commands like “do not drive.” Combined with the social and professional pressures of commuting, many residents stayed on the move despite the risks. The storms also had serious economic effects. Visits to shopping malls and recreational sites dropped by up to 40 percent, reducing consumer activity. Long-distance trips into the central business district plummeted, though the CBD itself remained relatively stable thanks to the subway system. Still, suspended flights and severed links to New Chitose Airport struck a blow to tourism and business, underscoring how local mobility failures ripple into the wider economy.

Planning for Future Resilience

The authors conclude that policymakers must rethink resilience strategies. Japan’s emergency road network, designed with earthquakes in mind, does not fully address snow-related disruption. Facilities such as shelters, hospitals, and rescue centers should be placed with real mobility communities in mind, since travel clusters often cut across administrative borders. Maintaining strong connections between the city center and its peripheries, or even building ring roads, could prevent collapse. Commercial hubs should be seen not only as retail spaces but also as vital nodes in the social and transportation fabric. While the study analyzed only twelve days of data and lacked hourly resolution, its message is clear: snowstorms do more than slow traffic, they rewire the city’s structure of movement.

In Sapporo, the storms fractured a sprawling network into isolated pockets of activity, exposing the limits of a monocentric design. For residents, the snow meant canceled outings, curtailed travel, and disrupted routines. For planners, it highlights the urgent need for smarter warnings, resilient infrastructure, and disaster strategies grounded in how people actually move when nature takes control.