Breakdown of Lähijunan saapuessa meidän pitää juosta laiturille.
me
we
juosta
to run
saapua
to arrive
pitää
must / have to
Questions & Answers about Lähijunan saapuessa meidän pitää juosta laiturille.
How does Lähijunan saapuessa mean "when the commuter train arrives"?
This is the active temporal construction, which is a concise way to say "when something happens" in Finnish. It uses the 2nd infinitive of the verb saapua (to arrive) in the inessive case, creating saapuessa. You can think of it as literally meaning "in the arriving of".
Why is the word for commuter train in the genitive case (lähijunan)?
In a temporal construction, the subject of the action (the thing doing the arriving) must be put into the genitive case. Because the train is the one arriving, lähijuna becomes lähijunan. Together with the verb, it literally translates to "in the commuter train's arriving".
Why is it "meidän pitää" instead of "me pitää"?
This is a quick refresher on necessity sentences. Verbs that express having to do something, like pitää or täytyy, require the person who must do the action to be in the genitive case. Therefore, the pronoun me (we) becomes meidän.
Why do we use the allative case laiturille (onto the platform) instead of the illative case laituriin (into the platform)?
In Finnish, a platform or pier (laituri) is treated as an open, flat surface rather than an enclosed space. When you move towards or onto an open surface, you use the outer location cases, so "to the platform" takes the allative case (-lle).