Ruuhka vähentyy illalla.

The rush decreases in the evening.

Breakdown of Ruuhka vähentyy illalla.

• illalla: in the evening
• ruuhka: the rush
• vähentyä: to decrease

Questions & Answers about Ruuhka vähentyy illalla.

What exactly does ruuhka mean here? Is it one traffic jam, rush hour, or traffic in general?

Ruuhka literally means congestion, traffic jam, or rush‑hour traffic.

In this short, generic sentence, ruuhka is best understood as the rush‑hour traffic / the traffic congestion in general, not one specific jam.

Compare a few uses:

• Tiellä on ruuhka. – There is a (bad) traffic jam on the road.
• Aamulla on kova ruuhka. – In the morning there is heavy rush‑hour traffic.

So the word itself is singular, but depending on context it can refer to:

• one specific jam, or
• the general state of congestion, like in the target sentence.

Why is there no word for the or a before ruuhka? How do you know if it is the traffic or a traffic jam?

Finnish simply does not have articles like a/an or the.

• Ruuhka vähentyy illalla.
  → could be translated as The traffic decreases in the evening or Traffic gets lighter in the evening.

Whether you understand it as the traffic, rush‑hour traffic, or just traffic in general comes entirely from context, not from any special word in Finnish.

What grammatical form is ruuhka in, and why? Could it be ruuhkaa instead?

In Ruuhka vähentyy illalla, ruuhka is in nominative singular.

• It is the grammatical subject of the sentence, so it appears in the basic (nominative) form.

You could use ruuhkaa (partitive) in a different kind of sentence:

• Illalla on vähemmän ruuhkaa. – There is less traffic in the evening.

Here, ruuhkaa is partitive because it is an indefinite quantity (less of something).
In the original sentence the focus is on what the subject does (the congestion decreases), so the subject is nominative: ruuhka.

What form of the verb is vähentyy, and what is its dictionary (infinitive) form?

The verb form vähentyy is:

• present tense
• 3rd person singular
• of the verb vähentyä (to lessen, to be reduced, to decrease on its own).

So in a dictionary you will find vähentyä.

Roughly:

• vähentyä – to decrease (intransitive; something decreases by itself)
• ruuhka vähentyy – the traffic decreases / gets less.

Why does vähentyy end with -yy? How is it formed and pronounced?

The infinitive is vähentyä. When conjugated in the 3rd person singular present, verbs of this type typically form -tyy / -ttyy:

• syntyä → syntyy (to be born → is born)
• päättyä → päättyy (to end → ends)
• vähentyä → vähentyy (to decrease → decreases)

Spelling and pronunciation:

• y is a front vowel (similar to French u in lune).
• yy is a long version of that vowel.
• So vähentyy is pronounced with a long final vowel: vähentyy [ˈʋæhentyː].

The doubled vowel in Finnish generally marks vowel length, not a change of quality.

What is the difference between vähentyä, vähentää, and vähetä? When would I use each?

These are closely related verbs, but they differ mainly in transitivity and nuance:

1. vähentää – to reduce, to lessen something (transitive)

   • Requires an object; someone or something actively reduces something.
   • Hallitus vähentää veroja. – The government is cutting taxes.

2. vähentyä – to decrease, to be reduced (intransitive)

   • No object; something decreases by itself (or as a result of some action, but unstated).
   • Ruuhka vähentyy illalla. – The congestion decreases in the evening.

3. vähetä – also to decrease, to diminish (intransitive)

   • Very similar in meaning to vähentyä, often a bit more neutral/everyday.
   • Ruuhka vähenee illalla. – The traffic decreases in the evening.

In many everyday contexts, vähentyy and vähenee can both be used with almost the same meaning.
Vähentää, however, is clearly different because it normally takes an object.

Could I say Ruuhka vähenee illalla instead of Ruuhka vähentyy illalla?

Yes, Ruuhka vähenee illalla is also correct and natural.

• vähenee is the 3rd person singular present of vähetä.
• vähentyy is the 3rd person singular present of vähentyä.

Both verbs mean that the amount or intensity of something becomes less.
In many contexts the difference is slight; Ruuhka vähenee illalla and Ruuhka vähentyy illalla can usually be translated the same way in English.

What case is illalla, and how does it correspond to the English in the evening?

Illalla is the adessive singular form of ilta (evening).

• ilta – evening (nominative)
• illalla – (on) the evening, in the evening (adessive)

In time expressions, Finnish often uses the adessive to express at/on (a time of day):

• aamu → aamulla – in the morning
• päivä → päivällä – in the daytime
• ilta → illalla – in the evening
• yö → yöllä – at night

So illalla directly corresponds to English in the evening.

Why is it illalla and not illassa? What is the difference?

Both forms exist, but they are used differently:

• illalla – adessive; standard for time of day: in the evening.
• illassa – inessive; literally in the evening as in inside an evening (event, program).

Examples:

• Ruuhka vähentyy illalla. – The traffic decreases in the evening.
• Konsertin illassa oli hyvä tunnelma. – The concert evening had a good atmosphere.

So for general time expressions like in the morning/evening/night, Finnish uses aamulla, illalla, yöllä, not aamussa, illassa, yössä.

Can I change the word order to Illalla ruuhka vähentyy? Does that change the meaning?

Yes, Illalla ruuhka vähentyy is perfectly correct.

Word order in Finnish is relatively flexible. Changing it usually affects emphasis rather than basic meaning.

• Ruuhka vähentyy illalla.
  – Neutral: the subject ruuhka is the starting point.
• Illalla ruuhka vähentyy.
  – Puts a bit more emphasis on illalla, as if contrasting with some other time (for example, In the evening traffic decreases, but in the morning it is bad).

Both sentences still mean that in the evening, the congestion decreases.

Does vähentyy here talk about the present or the future? Could it mean will decrease?

Finnish uses the present tense very often where English might use either the present or future.

Ruuhka vähentyy illalla can be understood as:

• The traffic decreases in the evening (general statement), or
• The traffic will decrease this evening (future reference), depending on context.

There is no special future tense in Finnish; context plus adverbs like huomenna (tomorrow), ensi viikolla (next week), or illalla (this evening) usually make the time reference clear.

If I want to say In the evenings, the traffic usually gets lighter, how would I change the sentence?

To express a habitual action (in the evenings in general), Finnish often uses an adverb like iltaisin:

• Iltaisin ruuhka vähentyy.
• Iltaisin ruuhka vähenee.

Both can be translated as:

• In the evenings, the traffic (usually) gets lighter.

illalla often refers to a specific or known evening or to evening as a time on a given day, whereas iltaisin clearly signals a repeated, habitual situation.

How would I say There is less traffic in the evening using ruuhka?

A natural way to say that is:

• Illalla on vähemmän ruuhkaa.

Breakdown:

• Illalla – in the evening (adessive)
• on – there is / is
• vähemmän – less
• ruuhkaa – traffic (partitive; an indefinite amount)

So: Illalla on vähemmän ruuhkaa ≈ There is less traffic in the evening.

This sentence structure is different from Ruuhka vähentyy illalla, but expresses a very similar idea.