El autobús tarda treinta minutos en llegar al campus si no hay tráfico.

Tardar means to take time or to be slow in doing something.

In this sentence, El autobús tarda treinta minutos... literally means The bus takes thirty minutes...

A very common pattern is:

• tardar + amount of time + en + infinitive

For example:

• Tardo diez minutos en llegar. = I take ten minutes to arrive.
• Se tarda una hora en coche. = It takes an hour by car.

So tarda is the third-person singular present form, matching el autobús.

After tardar, Spanish normally uses en + infinitive to say how long it takes to do something.

So:

• tarda treinta minutos en llegar = it takes thirty minutes to arrive

This is a fixed and very common structure:

• Tardo cinco minutos en vestirme. = I take five minutes to get dressed.
• Tardamos dos horas en terminar. = We took / take two hours to finish.

Without en llegar, the sentence would feel incomplete if you want to say what takes thirty minutes.

Because a + el contracts to al in Spanish.

So:

• a el campus → al campus

This contraction is required almost all the time.

The only common contraction with an article in Spanish is:

• a + el = al
• de + el = del

Examples:

• Voy al centro.
• Llego al campus.
• Vengo del trabajo.

In Spanish, llegar usually goes with a when you say the destination:

• llegar al campus
• llegar a casa
• llegar a Madrid

So en llegar al campus means in arriving at / to the campus, which in natural English becomes to get to the campus or simply to arrive at the campus.

One useful detail:

• With casa, Spanish usually says llegar a casa, not a la casa, unless you mean a specific house.

Hay means there is / there are, so no hay tráfico means there is no traffic.

Spanish uses hay to talk about existence:

• Hay un problema. = There is a problem.
• No hay clase hoy. = There isn’t class today.
• Hay mucho tráfico. = There is a lot of traffic.

Estar is used more for location or state, not for simple existence.

So:

• No hay tráfico = There is no traffic.
• Not no está tráfico

Because tráfico is being used in a general, uncountable sense, like traffic in English.

So:

• no hay tráfico = there’s no traffic

This is similar to:

• Hay agua. = There is water.
• No hay tiempo. = There is no time.
• Hay comida. = There is food.

If you add an article, the meaning changes or becomes more specific:

• el tráfico = the traffic, traffic in general as a concept, or specific traffic being discussed

But after hay, it’s very common to leave mass nouns without an article.

Because this is a real, possible condition: if there isn’t traffic.

Spanish uses si + present indicative for normal real conditions in the present or future:

• Si no hay tráfico, llegamos pronto.
• Si tengo tiempo, voy contigo.

So here:

• si no hay tráfico = if there is no traffic

You do not use the subjunctive after si in this kind of sentence.

Yes, absolutely.

Spanish can put the si-clause at the beginning or at the end:

• El autobús tarda treinta minutos en llegar al campus si no hay tráfico.
• Si no hay tráfico, el autobús tarda treinta minutos en llegar al campus.

Both mean the same thing. The difference is mainly one of focus or style.

If the si-clause comes first, a comma is normally written:

• Si no hay tráfico, ...

If it comes second, no comma is usually needed:

• ..., si no hay tráfico.

Because after tardar, the duration comes directly:

• tardar + amount of time + en + infinitive

So:

• tarda treinta minutos en llegar
• tardo dos horas en hacerlo

You do not say tarda en treinta minutos in this structure.

Compare:

• Tarda treinta minutos en llegar. = It takes thirty minutes to arrive.
• Llega en treinta minutos. = It arrives in thirty minutes.

Those are different structures.

Yes, and it would be natural, but the emphasis is slightly different.

• El autobús tarda treinta minutos en llegar al campus focuses on the amount of time the journey takes.
• El autobús llega al campus en treinta minutos focuses more on the result / arrival within that time.

In many everyday situations, they are very close in meaning.

Still, tardar + tiempo + en + infinitive is especially useful because it is a very common Spanish way to say it takes X time to do Y.

In Spanish, it is very normal for the thing making the journey to be the subject:

• El autobús tarda treinta minutos...
• El tren tarda una hora...
• El vuelo tarda dos horas...

English can do this too:

• The bus takes thirty minutes.

So although it may feel a little different from It takes thirty minutes by bus, the Spanish structure is completely standard.

Campus is used in Spanish as a noun meaning campus, and it is normally masculine:

• el campus
• al campus

This is just something you learn with the noun. Many borrowed nouns in Spanish take a grammatical gender, and campus is commonly masculine.

The accent marks show which syllable is stressed.

• autobús → stress on the last syllable: au-to-BÚS
• tráfico → stress on the first syllable: TRÁ-fi-co

These accents follow Spanish spelling rules and help with pronunciation.

A learner should especially notice that:

• autobús is not stressed like English AU-to-bus
• tráfico is not tra-FI-co

The written accents tell you exactly where the stress goes.