The UIAA mountaineering and climbing accidents case law database now includes reports from 20 different cases. These are drawn from accidents which took place in 14 different countries and on five continents.
The latest featured case study concerns a slackline accident which occurred on a public sports ground in Germany.
Case Study: Karlsruhe – Slackline Accident on Public Sports Ground
In this judgment, the Higher Regional Court of Karlsruhe clarified the scope of the German “traffic safety obligations” (Verkehrssicherungspflichten) applicable when individuals install recreational equipment in public spaces. The case concerned a slackline tensioned at knee height between two trees in a city park, creating a hidden obstacle for other users of the shared path. A cyclist, unable to detect the slackline from a reasonable distance, collided with it and sustained injuries.
The Court held that the person who installed the slackline had created a foreseeable source of danger and therefore bore a duty to ensure that the installation was either clearly visible or appropriately secured. Because no warning measures were taken and the slackline constituted an unexpected hazard for third parties, the installer was found liable for the accident under § 823(1) BGB. (general civil liability).
The decision reinforces the principle that even informal, non-commercial outdoor recreation is subject to traffic safety obligations whenever third parties may encounter unforeseen risks. The ruling underscores that those who introduce obstacles into public environments must prevent avoidable harm regardless of the recreational, voluntary or non-professional context of the activity.
Summary of the Facts
The events took place in a public park in Karlsruhe, where the defendant had installed a slackline between two trees at approximately knee height. The slackline was positioned across a grassy area adjacent to a path routinely used by pedestrians and cyclists. Due to the angle of approach and the color and height of the line, it was not visible to users of the path until they were very close to it.
A cyclist entered the park and followed the shared path in normal daylight conditions. As she approached the grassy area, she did not perceive the slackline and collided with it, being thrown from her bicycle and sustaining injuries. Emergency services were called, and she later sought compensation for medical expenses, pain and suffering, and material losses.
The injured cyclist (claimant) brought a civil action against the person who had installed the slackline (defendandt), alleging that it constituted a hidden and unexpected obstacle in an area open to public use. The defendant argued that slacklining was a common recreational activity in parks and that the cyclist should have been attentive to her surroundings.
In first instance, the court ruled in favor of the cyclist, finding that the slackline installer had breached their traffic safety obligations by creating a foreseeable hazard without implementing any warning measures. The defendant appealed the decision to the Higher Regional Court of Karlsruhe (Oberlandesgericht Karlsruhe), which upheld the lower court’s findings and confirmed liability.
Reasoning Summary
The Higher Regional Court of Karlsruhe based its judgment on the German doctrine of traffic safety obligations (Verkehrssicherungspflichten). The Court held that anyone who introduces a potential hazard into a public space must take reasonable precautions to prevent foreseeable harm. This duty applies irrespective of whether the activity is recreational or non-commercial.
Relying on expert evidence, the Court found that the slackline, set at knee height and difficult to detect from a distance, constituted a hidden and unexpected obstacle for users of the park’s shared path. Because the installer failed to take basic precautionary measures—such as ensuring sufficient visibility or providing warnings—the Court concluded that he breached his duty of care under § 823(1) BGB.
The Court rejected the defendant’s arguments that slacklining is a common practice not requiring safety measures and that the cyclist should have been more attentive. It held that the cyclist could not reasonably anticipate such an obstacle and that no contributory negligence applied. The appellate court therefore confirmed the first-instance judgment and upheld the defendant’s liability.
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In addition to the synopsis above, the UIAA Legal Affairs Commission – responsible for managing the database – highlight the following areas as part of its complete case report – the legal framework/analysis; summary of the facts; summary of the arguments of the parties; a reasoning summary; as well as the LAC’s own reflections on the judgement which is as follows:
This judgment clearly illustrates how general traffic safety rules apply when recreational activities take place in public spaces. The Court confirmed that a slackline stretched across a shared-use path constitutes a traffic obstruction and that users must ensure their equipment does not create hidden hazards for others.
A significant aspect of the decision is the emphasis on visibility and avoidability. Expert reconstruction showed that the slackline was practically undetectable until very close, which led the Court to reject any contributory negligence. The case highlights the value of technical evidence when assessing the foreseeability of an obstacle.
From a practical standpoint, the ruling clarifies that leaving a slackline unmarked and unattended in a public area can amount to gross negligence, even if the activity itself is low-risk. It reinforces that outdoor users must consider their impact on all other users of a shared environment.
LAC notes that the reasoning aligns with other cases in the database involving unexpected obstacles or unsafe setups in shared spaces, underscoring the importance of adequate marking, supervision, and hazard awareness in recreational settings.
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To access the database please click here.
The database also provides the opportunity for users to submit cases for inclusion.
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Main photo: Slackline, for illustrative purposes only. Credit: Shutterstock