Characteristics of pedestrians descending on a stairway: A trajectory-based empirical analysis

•Microscopic movement characteristics of pedestrians on the stairs are analyzed.•Pedestrian lane formation on the stairs is quantified.•Spatial characteristic of the nearest neighbor on the stairs is investigated.•Pedestrian individual fundamental diagram on the stairs is derived.•The degree of congestion and intrinsic risk for stair movements is measured using congestion level and crowd danger.