Vi var tvungna att åka taxi, eftersom tåget inte kom.

Swedish usually uses vara tvungen att + infinitive to express necessity in the past. So Vi var tvungna att åka taxi is the natural way to say We had to take a taxi.

Måste is mainly used for present-time necessity, and it normally does not give a clear completed-past meaning in a sentence like this. That is why var tvungna att is preferred here.

Because tvungen behaves like an adjective and agrees with the subject.

The forms are:

• tvungen for singular common gender
• tvunget for singular neuter
• tvungna for plural

Since vi means we, the plural form tvungna is used.

That is part of the fixed pattern vara tvungen att + infinitive.

So:

• Jag är tvungen att gå
• Hon var tvungen att ringa
• Vi var tvungna att åka taxi

In English, this corresponds to to in had to go / was forced to go, but in Swedish the att is required in this construction.

Åka is commonly used for traveling by some kind of vehicle or transport. So åka taxi means go by taxi or take a taxi.

You would not normally use gå here, because gå means walk or go on foot. Since a taxi is a vehicle, åka is the natural verb.

After verbs of travel like åka, Swedish often uses the transport word without an article:

• åka buss
• åka tåg
• åka bil
• åka taxi

So åka taxi means travel by taxi in a general way. Swedish often treats the means of transport as an uncounted travel method in this pattern.

Yes. Both are possible, but they feel slightly different.

• åka taxi focuses on the mode of transport
• ta taxi means take a taxi, and is also very common
• ta en taxi can sound a little more concrete, as if you are choosing or hailing one taxi

So Vi var tvungna att åka taxi and Vi var tvungna att ta taxi are both natural.

Eftersom means because or since. It introduces the reason for the first part of the sentence.

So the structure is:

• Vi var tvungna att åka taxi = what happened
• eftersom tåget inte kom = why it happened

It introduces a subordinate clause, and that affects word order.

Because after eftersom, Swedish uses subordinate clause word order.

In a subordinate clause, inte normally comes before the finite verb:

• eftersom tåget inte kom

In a main clause, it would be:

• Tåget kom inte

So this is a very important Swedish pattern:

• main clause: verb before inte
• subordinate clause: inte before the verb

Tåget means the train, with the definite ending -et.

That is used because the sentence is talking about a specific train that the speakers were expecting. If you said ett tåg, it would mean a train, which sounds much less specific and would not fit the situation as well.

Kom is the past tense of komma, and in everyday Swedish it is very common to use komma for something arriving or showing up.

So tåget inte kom literally looks like the train did not come, but in natural English the idea is often the train didn’t arrive or the train didn’t show up. This is normal Swedish usage.

Not always. Swedish often allows both versions:

• Vi var tvungna att åka taxi, eftersom tåget inte kom.
• Vi var tvungna att åka taxi eftersom tåget inte kom.

The comma here mainly marks a pause and can be a style choice. In a short sentence like this, leaving it out is also perfectly normal.