渋谷で電車をのりかえなければならない。

indicates location of action; at; in; indicates time of action; indicates means of action; cause of effect; by; and then; so; indicates continuing action; indicates certainty, emphasis, etc.

train; electric train

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to transfer (trains); to change (bus, train); to change one's mind; to move on to (e.g. a new love interest); to change methods; to change one's way of thinking