Is my interpretation of this phrase correct? ええ、道の横を川が流れているんです

Question

ええ、道の横を川が流れているんです。(context)

So, as I understand it, the sentence says that the river flows across the horizontal (axis?) of the street. Is that correct? I'm really confused by this way of expressing that A crosses B. Since it feels very complicated and unnatural to me, I'm afraid that I don't understand it correctly, even more so because in context of the dialogue, they don't really pick up that information further down.

This also poses a problem for me because を appears in a function I didn't really encounter so far.

When used in context of directions, I found it as a marker for going along something "道を行く" or inside of something "公園を散歩する", sometimes also in the function of crossing something like 交差点を渡る。 But this feels like a mix because its like going along the horizontal of the street.

Answer 1

In the dialogue, サントス doesn't understand what 「川沿い」 (along the river) means so the passerby explains that 「道の横を川が流れている」 (a river runs next to the road).

In the sentence, 「を」 indicates that 「道の横」 is the object of "river running" so it might seem weird in a word-to-word translation such as "river runs the side of a road".

Answer 2

In fact, 道の横 means along the track. According to the dialogue you provided you can see that when the passenger said 川沿いに行くと… Santos doesn't understand so (s)he changes his/her words to 道の横に川が流れる (A river goes along the path) その川に沿って行って (follow this river).

This is the 4th definition of 横:

４ 物のかたわら。脇。「―の席に座る」「―を見る」