Traffic or transportation: movement of people and goods and the systems (roads, trains, buses) that carry them.
朝の通勤時間帯は交通が非常に混雑する。
Traffic is extremely congested during the morning commute.
新しい橋ができて、地域の交通が便利になった。
With the new bridge, transportation in the area became more convenient.
交通事故に気をつけて運転してください。
Please drive carefully to avoid traffic accidents.
Communication or exchange: the interchange of information, ideas, or people (often in a somewhat formal or literary register).
学者間の交通が活発になり、研究が進んだ。
Communication among scholars became active, advancing research.
戦前は海外との交通が限られていた。
Before the war, exchanges with overseas were limited.
Intercourse or social intercourse — interaction between people; a broad, somewhat literary usage.
国際的な文化交通は相互理解を深める。
International cultural intercourse deepens mutual understanding.