1. A method for ascertaining at least one road-related information item, comprising: ascertaining, by a processing device, a position of a location on a road, starting from which a mobile user device of a communication network crossed the road, based on position data of the user device; ascertaining, by the processing device, a speed of the user device at least one of before the crossing, during the crossing, and after the crossing; ascertaining, by the processing device, a waiting time during which the user device had to wait at the location before the user device crossed the road; and ascertaining, by the processing device, a position of a light signal system as the road-related information item, based on the ascertained waiting time and the ascertained position; based on the ascertained user device speed, ascertaining, by the processing device, which type of traffic-light system, selected from a plurality of traffic-light system types, the light signal system is, the plurality of traffic-light system types including a pedestrian traffic light and a light signal system for vehicles; and updating a digital map with the road-related information item.