In this situation, are you obliged to use the sound signal to warn children not to run into the roadway?

In the video, you are driving along a small street in a town next to a park; on the left, adults with children are walking on the grass by the edge of the roadway, and the road ahead of you is clear. You do not have to use the horn to warn the children. The answer is: no.

The Road Traffic Act allows you to use the horn only when it is necessary to warn of danger and prohibits misusing it; in a built-up area using the horn is prohibited, unless it is necessary because of immediate danger. The children are walking under the care of adults and are not running onto the roadway - there is no immediate danger, so there is no reason to sound the horn; the horn could frighten them and cause exactly what you want to avoid. Instead of a signal, you use caution: you slow down, increase your distance from the kerb, keep your foot over the brake and watch the group, because a child may pull away from an adult and run onto the roadway after a ball or a friend. You will use the horn only when a child actually starts moving towards the roadway and a warning can prevent an accident.

Legal basis: Art. 29 para. 1 and para. 2 point 1 and 2 and Art. 3 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)