Para llegar al campus, hubo que hacer un transbordo y validar el abono dos veces.

Hubo que + infinitive means it was necessary to... or ...had to be done.

So hubo que hacer un transbordo means something like:

• it was necessary to make a transfer
• we had to change lines
• a transfer was required

This structure is impersonal. It does not say exactly who had to do it. English often uses we had to, but Spanish can leave that unsaid.

Because haber que and tener que work differently:

• haber que + infinitive = an impersonal necessity; the focus is on what was necessary in general
• tener que + infinitive = a personal obligation; it tells you who had the obligation

Compare:

• Hubo que hacer un transbordo.
  = A transfer had to be made / It was necessary to change.
• Teníamos que hacer un transbordo.
  = We had to make a transfer.

In your sentence, the speaker is describing the travel situation rather than emphasizing we.

This is a preterite vs imperfect choice.

• hubo que presents the necessity as a completed past event
• había que presents it as ongoing, background, or habitual

Here, the sentence is about one specific trip to campus, so hubo que fits well:

• Para llegar al campus, hubo que...
  = To get to campus, it turned out that it was necessary to...

If you said había que, it would sound more like a general situation or background description:

• Para llegar al campus, había que hacer un transbordo.
  = To get to campus, you had to make a transfer / it was necessary to make a transfer

That version is also possible, but it feels less like a single completed episode.

Para + infinitive often expresses purpose or what was needed in order to do something.

So:

• Para llegar al campus = To get to campus / In order to get to campus

It sets up the situation first, and then the sentence explains what was necessary.

A native English speaker might want to translate it very literally, but in Spanish this opening is extremely natural.

Because a + el contracts to al.

So:

• a el campus → al campus

This contraction is required in normal Spanish, except with certain cases like proper names where the article is part of the name.

In Spanish, places often take a definite article where English may not emphasize one.

• llegar al campus = arrive at the campus / campus

Here el campus is treated as a specific place known to the speaker and listener.

Also, campus in Spanish is commonly used as a masculine noun:

• el campus
• los campus

Transbordo is a public-transport word meaning transfer, especially when you have to change:

• from one metro line to another
• from one bus to another
• from one train/service to another

So hacer un transbordo means to make a transfer or to change lines/services.

In Spain, this is very common transport vocabulary.

Spanish often uses hacer + noun where English might prefer a single verb or a shorter expression.

So:

• hacer un transbordo = make a transfer

This is a normal, natural way to say it in transport contexts.

You may also hear related expressions, but hacer un transbordo is straightforward and idiomatic.

In this sentence, abono means a travel pass, transport pass, or season ticket.

In Spain, abono is commonly used for a pass that lets you travel repeatedly for a period of time, such as:

• a monthly metro pass
• a youth transport pass
• a regional travel pass

So el abono here is not something like cash payment. It is the pass/card being used for transport.

Because with a transport pass, you may already have paid for the service in advance. What you still need to do is validate it, meaning:

• tap it
• scan it
• stamp it
• activate/check it at the gate or machine

So:

• pagar = to pay
• validar = to validate / tap in / have the pass registered

In Spain, validar is very common wording for public transport.

Spanish can say twice as dos veces.

Literally, it is two times:

• una vez = once
• dos veces = twice
• tres veces = three times

So validar el abono dos veces means to validate the pass twice.

Because it modifies the action validar el abono and sounds natural at the end of the clause:

• validar el abono dos veces

Spanish often places this kind of frequency expression after the verb phrase.

Other word orders may be possible in some contexts, but this one is the most neutral and natural here.

The comma separates the introductory phrase from the main clause:

• Para llegar al campus, = introductory context
• hubo que hacer un transbordo... = main statement

In English, this is similar to writing:

• To get to campus, we had to...

The comma helps readability. In short introductory phrases, Spanish punctuation can sometimes vary, but here it is very natural.

Because Spanish does not always need to state the subject, and here the structure is deliberately impersonal.

The sentence is not really about who did it; it is about what was required to get to campus.

That is why hubo que works well: it keeps the focus on the travel steps, not on the people.

In natural English, we would often supply we:

• To get to campus, we had to make a transfer and validate the pass twice.

But Spanish does not have to say nosotros here.