appearance diesel engine equipment locomotive machinery marshalling-yard mobility motion move moving power rails railway railway-yard restoration restoration-yard strength Copenhagen Denmark escalator HDR metro Nyberg staircase subway train transport tube under ground urban advice alert announcement appropriate-behavior appropriate-behaviour aware awareness be-careful beware black care careful caution communicating communication concern danger dangerous directions forklift informing listen Look looking lookout moving-machinery observant rain rain-drops red risk risks safety sign signs trams warning warning-sign watch watch-out work workplace yellow city city square group pedestrians people shadows strolling students sun light sunny sunshine walking competing competition grass leaf looser race snail snailrace snails summer summerday winner commuting movement passenger scene scenery speed travel tunnel Underground architecture downward empty escalators metal progress solution stair stairs step steps transportation upward down going going down going up stairway travelling UP walk biker bikers motorbike Motorbikes motorcycle motorcycles ride rider Riders road