Hoy el tren de cercanías llega con retraso, así que voy a la universidad en autobús.

In Spain, el tren de cercanías usually means a commuter train or suburban rail train.

• tren = train
• de cercanías = for nearby areas / commuter-area service

So this is not just any train. It refers to the kind of train people often use to travel between a city and surrounding towns.

In Spain, Cercanías is also the name of a well-known commuter rail service, so learners often see this expression a lot.

Spanish often uses de + noun to describe the type or function of something.

So:

• tren de cercanías = commuter train
• literally, something like train of local/nearby services

This structure is very common in Spanish:

• tren de alta velocidad = high-speed train
• zumo de naranja = orange juice
• parada de autobús = bus stop

Using de here is just the normal Spanish way to specify what kind of train it is.

Llega con retraso is a very natural way to say that a train is arriving late or running late.

• llega = arrives / is arriving
• con retraso = with delay / late

Spanish often uses con retraso for transport:

• El vuelo llega con retraso.
• El tren sale con retraso.

You could also hear things like:

• El tren está retrasado = the train is delayed
• El tren llega tarde = the train arrives late

But llega con retraso sounds especially normal for trains, flights, and other services.

Both can relate to lateness, but they are not used in exactly the same way.

• tarde often means late
• con retraso means delayed or with a delay

Examples:

• Llego tarde. = I’m arriving late.
• El tren llega con retraso. = The train is arriving with a delay / is delayed.

For public transport, con retraso is often more idiomatic because it sounds like an official or service-related delay.

Because in Spanish, the present tense is very often used for:

• things happening right now
• things happening around now
• planned or real current situations

So in this sentence:

• Hoy el tren de cercanías llega con retraso = Today the commuter train is delayed / arrives late
• voy a la universidad en autobús = I’m going to university by bus

This is very similar to English, where we might also say:

• Today the train is late, so I’m going by bus.

Spanish does not need a separate continuous form here.

Yes, you could, but it changes the feel slightly.

• llega con retraso = neutral, general, very natural
• está llegando con retraso = more focused on the action right now, as if the arrival is in progress

For schedules, transport updates, and general statements, Spanish often prefers the simple present:

• El tren llega con retraso.

So the original sentence sounds very natural.

Así que means so, therefore, or so then.

It links a cause and a result:

• the train is delayed
• así que I go to university by bus

It is a very common connector in everyday Spanish.

They do different jobs.

• porque = because
• así que = so

Compare:

• Voy en autobús porque el tren llega con retraso.
  = I’m going by bus because the train is delayed.

• El tren llega con retraso, así que voy en autobús.
  = The train is delayed, so I’m going by bus.

So porque introduces the reason, while así que introduces the result.

The verb ir uses a before a destination:

• voy a casa
• voy al centro
• voy a la universidad

Here:

• voy = I go / I’m going
• a = to
• la universidad = the university

So a is required because it marks where you are going.

Because universidad normally takes an article when talking about the place as a destination:

• voy a la universidad
• estoy en la universidad

Spanish often uses the definite article in places where English may not:

• Voy al hospital.
• Está en la oficina.
• Vamos a la playa.

So a la universidad is the normal form.

Spanish only contracts:

• a + el = al
• de + el = del

But there is no contraction with la, los, or las.

So:

• a + el colegio = al colegio
• a + la universidad = a la universidad

That is why the sentence keeps a la.

Because en + means of transport usually appears without an article when you mean by that means of transport.

So:

• en autobús = by bus
• en tren = by train
• en coche = by car
• en metro = by metro

If you say en el autobús, it usually means on the bus or in the bus, referring to a specific bus as a place, not simply the method of transport.

Compare:

• Voy a la universidad en autobús. = I go to university by bus.
• Voy leyendo en el autobús. = I read while on the bus.

Normally, no. For means of transport, Spanish usually uses en:

• en autobús
• en tren
• en avión

Using por here would sound unnatural in standard Spanish.

Yes, autobús is completely standard in Spain.

You may also hear:

• bus or bús in some contexts, but autobús is the safer standard word for learners
• autocar for a coach / long-distance bus, depending on context

For Spain-focused Spanish, autobús is the best default choice here.

Putting Hoy first gives the sentence a natural time frame right away: Today...

Spanish word order is flexible, so you could also say:

• El tren de cercanías llega con retraso hoy...

But Hoy at the beginning sounds very natural because it sets the scene immediately.

It can also add a slight emphasis: today, specifically, the train is delayed.

It is very normal and helpful.

A comma is commonly used before connectors like así que because it separates the first idea from the result:

• Hoy el tren de cercanías llega con retraso, así que voy a la universidad en autobús.

Without the comma, the sentence would be harder to read. So the punctuation in the original sentence is good standard writing.

The accent marks show stress.

• así: stress on the last syllable
• autobús: stress on the last syllable
• universidad: no written accent, but the stress naturally falls according to Spanish stress rules

Very roughly:

• a-SÍ
• au-to-BÚS
• u-ni-ver-si-DAD

Accent marks matter in Spanish, so it is important to keep them in writing.

Yes. In Spanish, the simple present often covers both meanings, and the context tells you which one is intended.

• Voy a la universidad todos los días. = I go to university every day.
• Hoy voy a la universidad en autobús. = Today I’m going to university by bus.

In this sentence, hoy makes it sound like a specific trip today, so I’m going to university is the most natural interpretation.