Der Zugausfall unterbricht die Reisekette.

Zugausfall is a masculine noun, so its basic dictionary form is der Zugausfall.

In this sentence, der Zugausfall is the subject — the thing doing the action of interrupting — so it is in the nominative case. For a masculine noun in the nominative singular, the article is der.

A quick comparison:

• der Zugausfall = nominative masculine
• den Zugausfall = accusative masculine
• die Zugausfall = not correct for this noun

So der Zugausfall unterbricht ... means the train cancellation/disruption interrupts ...

Yes. Zugausfall is a compound noun, which is very common in German.

It is made from:

• der Zug = train
• der Ausfall = cancellation, failure, outage, disruption

Together, der Zugausfall means something like:

• train cancellation
• cancellation of a train
• sometimes more generally train disruption

German often combines nouns into one word where English would use two or more words.

Reisekette is a feminine noun, so its dictionary form is die Reisekette.

In this sentence, it is the direct object of unterbricht, so it is in the accusative case. For feminine singular nouns, the article is die in both the nominative and the accusative.

So:

• nominative: die Reisekette
• accusative: die Reisekette

That is why the form does not change here.

It is another compound noun:

• Reise = journey, trip, travel
• Kette = chain

So literally it means travel chain or journey chain.

This is often used for the sequence of connected parts in a trip, for example:

• getting to the station
• taking the train
• changing trains
• continuing to the destination

So the word suggests that a journey consists of linked steps, like links in a chain.

Because the subject is der Zugausfall, which is third person singular.

The infinitive is unterbrechen = to interrupt.

In the present tense:

• ich unterbreche
• du unterbrichst
• er/sie/es unterbricht
• wir unterbrechen
• ihr unterbrecht
• sie/Sie unterbrechen

Since der Zugausfall is like er grammatically, German uses:

• der Zugausfall unterbricht

No. In this meaning, unterbrechen is inseparable.

So you do not split it:

• correct: Der Zugausfall unterbricht die Reisekette.
• not correct: Der Zugausfall bricht die Reisekette unter.

That is important because many German prefix verbs are separable, but unterbrechen meaning to interrupt is not.

You can also see this in forms like the past participle:

• unterbrochen not untergebrochen

Because German main clauses normally follow the V2 rule: the finite verb comes in the second position.

Here the sentence is:

• Der Zugausfall | unterbricht | die Reisekette

Position 1: Der Zugausfall
Position 2: unterbricht

This is standard German word order for a statement.

You could also move another element to the front, but the verb would still stay second:

• Die Reisekette unterbricht der Zugausfall.
  This is grammatical, but much less natural here.

The articles help you.

• der Zugausfall = nominative masculine → subject
• die Reisekette = accusative feminine here → object

Also, the meaning of the verb helps:

• the train cancellation interrupts
• the travel chain is interrupted

So:

• subject: der Zugausfall
• object: die Reisekette

In German, case marking often tells you who is doing the action and who is receiving it.

Yes. A very natural passive version would be:

Die Reisekette wird durch den Zugausfall unterbrochen.

That means: The travel chain is interrupted by the train cancellation.

Notice the changes:

• die Reisekette becomes the grammatical subject
• durch den Zugausfall expresses the cause/agent
• den Zugausfall is accusative after durch

Both versions are correct, but the original active sentence is more direct.

It is understandable and correct, but it sounds a bit more like:

• transport planning
• customer information
• logistics
• formal travel language

In everyday speech, people might more often say something simpler depending on context, such as:

• Die Reise wird unterbrochen.
• Die Verbindung ist unterbrochen.
• Der Zugausfall stört die Weiterreise.

So Reisekette is a real word, but it is somewhat technical or formal in tone.

The plurals are:

• der Zugausfall → die Zugausfälle
• die Reisekette → die Reiseketten

Examples:

• Mehrere Zugausfälle unterbrechen den Verkehr.
• Digitale Tickets sollen Reiseketten vereinfachen.

Notice the umlaut in Zugausfälle.

A simple pronunciation guide would be:

dehr TSOOK-ouse-fall oon-ter-BRIKHT dee RYE-zuh-ket-tuh

A few helpful points:

• Zug begins with ts, not a z sound like in English zoo
• au in Ausfall sounds like ow in cow
• ch in unterbricht is the soft German ich sound
• Reise sounds roughly like RYE-zuh
• kette has a short e and a clear double tt

Yes, depending on the exact nuance.

Possible alternatives:

• stört = disturbs, disrupts
• verzögert = delays
• behindert = hinders
• unterbricht = interrupts, breaks the continuity

So:

• Der Zugausfall stört die Reisekette. = a bit more general
• Der Zugausfall verzögert die Reise. = focuses on delay
• Der Zugausfall unterbricht die Reisekette. = emphasizes that the chain of travel is broken

So unterbricht is a strong, precise choice if you want to show that the journey flow is broken.