交差 and 合流: intersecting paths and joining flows
Compare two roads intersecting in front of a station with two rivers merging in a valley, without inferring whether paths remain separate or join after crossing.
Read where the two roads meet in 交差
交差 (こうさ) describes paths or other things intersecting. This example concerns the relationship between two roads, rather than people moving on them.
“二本の道が駅前で交差している。” says that two roads intersect in front of the station. 二本の道 identifies the roads and 駅前 gives the location; the sentence does not describe their continuation after that point.
Read the joining of flows in 合流
合流 (ごうりゅう) can describe flows joining and continuing together. In the river example, read the merging relationship as well as the meeting point.
“二つの川が谷の奥で合流する。” says that two rivers merge deep in the valley. Unlike the sentence about intersecting roads, this word expresses the joining of the two flows.
Do not settle what happens after an intersection
交差 alone does not tell you whether the paths continue separately or as one route. Crossing and merging can occur at the same complex location, so do not treat them as mutually exclusive types of place.
“駅前で友人と合流して会場へ向かった。” describes joining a friend and heading to the venue together. Do not import those people’s shared movement or a change of direction into the separate sentence about two roads intersecting.
Does “二本の道が駅前で交差している。” establish whether the two roads then join or remain separate?
Show the answer and why
No. It states that the two roads intersect there. It does not describe the later route structure or people moving together; the joining of two flows is explicit in the separate river example with 合流.