ascending staircase; stairs going up
Refers to a staircase that goes upward, often contrasted with 下り階段 (descending staircase).
駅の上り階段はいつも混んでいる。
The ascending staircase at the station is always crowded.
Compound of 上り (のぼり, 'ascending') + 階段 (かいだん, 'stairs').