Zamknięcie parkingu po wypadku było ważne.

Zamknięcie is a verbal noun formed from the verb zamknąć (to close / to shut).

So:

• zamknąć = to close
• zamknięcie = the closing / closure

In this sentence, zamknięcie parkingu means the closure of the parking lot or closing the parking lot.

Polish often uses verbal nouns this way, just like English can say:

• Closing the parking lot was important
• The closure of the parking lot was important

So the sentence begins with a noun phrase because the subject is not an action in verb form, but the event/concept of closing.

Because zamknięcie requires the thing being closed to appear in the genitive case.

So:

• parking = parking lot / car park
• zamknięcie parkingu = closing of the parking lot

This is very common with verbal nouns in Polish. Compare:

• otwarcie sklepu = opening of the shop
• zniszczenie miasta = destruction of the city
• zamknięcie drzwi = closing of the door

So parkingu is the genitive singular form of parking.

The preposition po here means after, and when po means after, it takes the locative case.

So:

• wypadek = accident
• po wypadku = after the accident

This is a fixed pattern:

• po obiedzie = after lunch
• po pracy = after work
• po meczu = after the match

Even though the locative is often introduced with in/on/about, with po it commonly means after.

Because the subject zamknięcie parkingu po wypadku is grammatically neuter singular.

The key word is zamknięcie, and nouns ending in -cie are typically neuter. So the verb and adjective must agree with that noun:

• zamknięcie = neuter singular
• było = was (neuter singular past form)
• ważne = important (neuter singular form)

Agreement in Polish works like this:

• masculine: był ważny
• feminine: była ważna
• neuter: było ważne
• non-masculine personal plural: były ważne

So the form is determined by zamknięcie, not by parkingu or wypadku.

The dictionary form is ważny (important).

Adjectives change to match the noun they describe. Here are the singular forms:

• masculine: ważny
• feminine: ważna
• neuter: ważne

Since zamknięcie is neuter, we use ważne.

Yes. Parking is a normal Polish noun, borrowed from another language but fully established in modern Polish.

In Polish, parking usually means:

• parking lot
• car park

Its forms include:

• nominative: parking
• genitive: parkingu
• locative: parkingu

So zamknięcie parkingu is completely natural Polish.

Yes. Both are good ways to understand it.

The Polish sentence is somewhat flexible in English translation because zamknięcie can be rendered as:

• the closure
• closing

So possible translations include:

• Closing the parking lot after the accident was important.
• The closure of the parking lot after the accident was important.

The exact English wording depends on style, but the Polish meaning stays the same.

This is a very useful question.

Both come from to close, but they emphasize different things:

• zamknięcie = the closing, closure, a completed act/result
• zamykanie = closing, the process of closing

Very roughly:

• zamknięcie drzwi = the closing of the door / the fact that the door got closed
• zamykanie drzwi = the act/process of closing the door

In your sentence, zamknięcie parkingu sounds natural because it refers to the fact that the parking lot was closed, especially as a significant event after the accident.

Yes. Polish word order is more flexible than English, although different orders can change emphasis.

The neutral version here is:

• Zamknięcie parkingu po wypadku było ważne.

You could also say:

• Po wypadku zamknięcie parkingu było ważne.

This puts more focus on after the accident.

Because Polish uses case endings, the grammatical roles are still clear even when the order changes. However, not every order sounds equally natural, and the original sentence is a very normal one.

Not exactly.

Ważne means important, not literally necessary.

So the sentence says that closing the parking lot was important, not necessarily that it was absolutely required.

If you wanted necessary, Polish would more likely use:

• konieczne = necessary
• niezbędne = essential

So compare:

• było ważne = was important
• było konieczne = was necessary

That distinction matters in both Polish and English.