suffix
Suffix attached to nouns indicating movement or position along a linear feature such as a wall, river, road, or railroad. Often used with に (〜伝いに).
See also: 伝う
川伝いに歩いて行くと、小さな橋が見えた。
Walking along the river, I saw a small bridge.
線路伝いに駅まで歩いた。
I walked along the railroad tracks to the station.