One of the unmistakable signs of winter in Copenhagen is the appearance of distinctive guards around the trees along the main streets. They protect them from salt and slush - a minor but symbolic element. This is because it marks the start of the winter maintenance season, in which bike paths are given priority.
The first snow not only makes it official to include Mariah Carey already, but also a collective surprise. Theoretically, it should also trigger the city's winter management system, but we know how it is - anyone who has tried to get around on foot or on a bicycle crossing the snow moguls on the side of the road is not happy about the snow. However, there is a place where equipment also goes out to the sidewalks and bike paths, and faster than on the roadways. This is Copenhagen and neighboring Frederiksberg, both of which boast an approach to winter street maintenance as part of their critical infrastructure.
bicycles always first
Success is enshrined in the fact that these municipalities divide all roads and routes into three levels of service, and the bicycle network here goes into the highest category. This means that snow removal and de-icing on bicycle routes are carried out around the clock, often faster than on automobile arteries. The goal is to ensure passability by 8:00 a.m., when statistically 400,000 residents get on their bikes.
If even a portion of them could not use a bicycle, public transportation would immediately be at capacity (as we are well aware, after all). Maintenance is therefore a transportation strategy to avoid traffic chaos.
With an extensive fleet of winter maintenance equipment at its disposal, the city sends both large road vehicles, medium-sized machines for larger sections, and the smallest ones - the most distinctive ones - sweepers and gritters that fit on bike paths. They are equipped with brushes at the front and salt spreading systems at the rear. They work almost continuously during snowstorms.
Although winter maintenance is an important part of city policy, winters in Denmark are becoming milder. Statistics show a marked decline in the number of days with snow covering more than half the country - from 33 days a year in 1961-1990 to just 3.6 days in 2019. In the last decade, the average is 8.3 days per year. Large plows have not been needed since the winter of 2012/2013. Nevertheless, the system remains prepared for rapid weather changes.
According to Anette Jerup Jørgensen, PhD in traffic sociology and a research consultant at the Danish Cyclists' Federation,
"The bicycle is the primary means of transportation for many Danes and is associated with freedom and flexibility. Therefore, weather is not seen as an obstacle. The advantages of cycling simply outweigh the inconvenience of riding in rain or snow."
In 2012, the city increased the annual budget for clearing snow from bike lanes by 2 million Danish kroner (270,000 euros). Although some Copenhageners still leave their bicycles at home, 80% of them still ride their bikes during the winter months.
More frequent snow removal and systematic sweeping are preventive measures, as poor maintenance standards are one of the factors that increase the risk of accidents, especially those involving cyclists. Regular removal of gravel, leaves, and in winter snow and ice - is the basis for safe bicycle infrastructure. This is probably one of the reasons why, despite the cold, short days and changeable weather, about 75% of Copenhagen cyclists continue to ride throughout the winter. When bike paths are cleared of snow and clean every day, cycling becomes the most predictable mode of transportation.
It is this normalization of daily cycling that has become one of the pillars of Copenhagen's mobility model. The infrastructure is supposed to be reliable at all times, even in winter.
salt, alternatives and restrictions
According to the regulations, winter maintenance covers different classes of routes. The paths most important to mobility must be maintained 24 hours a day. Lower classes include local, recreational or less trafficked routes. Any new bicycle development must include maintenance requirements. These standards are in addition to previously used standards for infrastructure widths and materials, infrastructure must also be designed for future maintenance work.
View this post on Instagram
The use of salt has been controversial for years, but there is currently no alternative that is as effective and economically viable for such a large-scale maintenance program. Admittedly, sprinkling with coffee is sometimes mentioned (it changes the PH of the soil), and other means, such as a solution based on beet juice (it's more expensive and smells very peculiar), are also being considered. That's why as early as 1985 there was official talk of the need to protect plants that were dying en masse due to salty soils and saltwater runoff from roadways*. A complete shift away from salt is unlikely, so the emphasis is shifting to protecting trees through proper planting site design, elevating planting beds, draining salt water into drains and using trunk guards, with it being better to plant fewer trees, but in conditions that give them a chance to survive, rather than duplicating an expensive replanting cycle.
It is worth mentioning, however, that although in Denmark the mass use of road salt intensified after 1960 (with the development of motorization and the increase in road maintenance standards), the other side of the coin soon became apparent, namely the serious side effects of roadside soil degradation, tree dieback and surface water pollution. Salt improves traffic safety in unstable winter conditions of fluctuating temperatures around zero, but it also causes costly damage to road surfaces and infrastructure, including bridges. In contrast, it was the economic crisis of the 1980s, along with the rising cost of repairs, that led to a halving of salt use and a renewed, more frequent use of sand, thereby forcing road users to accept slower driving.
Protecting trees with winter street maintenance
The City of Copenhagen takes into account the need to protect trees along major streets from the negative effects of snow removal measures when designing and maintaining road and bicycle infrastructure . In practice, this means installing guardrails to protect trees from salt and slush, but also ensuring adequate maneuvering space for maintenance equipment (this translates into minimum widths for streets and paths). The standard stipulates that the space above the route must be at least 2.8 meters high, allowing vehicles to pass without colliding with greenery or low branches. In addition, the minimum width of a bike path or bike lane located next to parked cars must be at least 2.0 meters. This standard is to ensure that grooming and snow removal can be performed without damaging trees or supporting infrastructure.
When planning new road projects or when renovating existing routes, the needs for care, winter maintenance and protection of greenery must be taken into account. Official guidelines ensure that bicycle and road infrastructure remains consistent, functional and compatible with elements of the urban landscape. As a result, trees growing along streets and bicycle routes are likely to survive.
Magdalena Milert
* Hvass, N. (1985). Defending street trees against road salt in Denmark. Journal of Arboriculture, 11(2), 61-64. accessed on: 14.12.2025.
