Cuando voy con mi hermana, el trayecto en tren se me hace más corto.

Because Spanish often uses the present tense to talk about something that happens regularly or whenever a situation occurs.

So Cuando voy con mi hermana means something like:

• When I go with my sister
• Whenever I go with my sister

It is not necessarily talking about one specific trip happening right now. It describes a habitual situation.

If it were about a specific past event, you would expect something like Cuando fui con mi hermana...

Cuando is used for when/whenever something happens. It introduces a time relationship.

• Cuando voy con mi hermana... = When/Whenever I go with my sister...

Si means if, so it would express a condition instead:

• Si voy con mi hermana... = If I go with my sister...

That changes the meaning. The original sentence is not presenting a condition; it is saying what happens on those occasions.

Trayecto usually means the journey segment, route, or trip from one place to another, often with emphasis on the stretch of travel itself.

In this sentence, el trayecto en tren refers to the train journey / the time spent on the train.

Compared with viaje:

• trayecto = the route or stretch of travel itself
• viaje = the trip more generally, often the whole experience

For example:

• El trayecto en tren dura dos horas = the train ride lasts two hours
• El viaje a Madrid fue estupendo = the trip to Madrid was great

Here, trayecto fits well because the sentence is about how long the train part feels.

El is used because the sentence refers to a specific, understood journey: the train journey that the speaker normally takes in that situation.

Spanish often uses the definite article where English might be more flexible.

So el trayecto en tren suggests:

• the train journey
• the journey by train
• the one we are talking about in this context

If you said un trayecto en tren, it would sound more like a train journey, less specific.

In Spanish, en + means of transport is the normal way to say by a vehicle:

• en tren = by train
• en coche = by car
• en autobús = by bus
• en avión = by plane

So el trayecto en tren literally means the journey in/on the train, but naturally it corresponds to the train journey or the journey by train.

This is a very common Spanish structure. Hacerse can mean to become, and with an indirect object pronoun it often means to seem / to feel to someone.

So:

• se me hace más corto = it feels shorter to me / it seems shorter to me

It is not saying the journey is objectively shorter. It is about the speaker’s perception.

Similar examples:

• La espera se me hizo eterna = the wait felt endless to me
• La clase se me hace larga = the class feels long to me

This is a very natural way in Spanish to talk about how time or an experience feels.

They do different jobs.

• me = to me
• se hace = part of the expression hacerse here

So the structure is basically:

• [something] se me hace + adjective

Meaning:

• [something] feels/seems + adjective to me

In this sentence:

• el trayecto en tren = subject
• se hace = feels/becomes
• me = to me
• más corto = shorter

A good way to understand it is:

• El trayecto en tren se me hace más corto
• The train journey feels shorter to me

With a conjugated verb, object pronouns usually go before the verb in Spanish.

So you get:

• se me hace

not

• se hace me

Spanish object pronouns such as me, te, le, nos normally come before a finite verb:

• me gusta
• te parece
• se me hace

They can attach to the end only with:

• infinitives: hacérseme in theory, though that would be unusual here
• gerunds: haciéndoseme, also not natural here
• affirmative commands

So in this sentence, se me hace is the standard order.

Más corto is the regular comparative form of corto:

• corto = short
• más corto = shorter

Spanish usually forms comparatives with:

• más + adjective
• menos + adjective

So:

• más largo = longer
• más difícil = more difficult
• más corto = shorter

In the sentence, it means the journey feels shorter than usual or shorter by comparison when the speaker goes with their sister.

Because corto agrees with trayecto, and trayecto is a masculine singular noun.

Agreement in Spanish means the adjective matches the noun in gender and number:

• el trayecto corto
• los trayectos cortos
• la ruta corta
• las rutas cortas

So in this sentence:

• el trayecto → más corto

If the noun were feminine, the adjective would change:

• la espera se me hace más corta

Yes. Several versions are possible, depending on what you want to emphasise.

For example:

• Cuando voy con mi hermana, el trayecto en tren se me hace más corto.
• Cuando voy en tren con mi hermana, el trayecto se me hace más corto.

Both are natural.

The original version highlights the train journey as a whole.
The alternative puts en tren earlier, inside the cuando clause, which can sound a bit more like when I travel by train with my sister.

Spanish word order is flexible, but different versions can slightly shift the focus.

Yes, you can, and it would sound natural.

The difference is mostly one of nuance:

• trayecto focuses more on the stretch of travel itself
• viaje is a broader word for the trip/journey

In many everyday contexts, both would work:

• El trayecto en tren se me hace más corto
• El viaje en tren se me hace más corto

The original with trayecto may sound a little more precise if you are talking specifically about the time spent traveling from A to B.

Yes, but Spanish usually omits subject pronouns unless they are needed for emphasis, contrast, or clarity.

So the normal version is:

• Cuando voy con mi hermana...

If you say:

• Cuando yo voy con mi hermana...

it sounds more emphatic, as if contrasting with someone else:

• Cuando yo voy con mi hermana, el trayecto se me hace más corto; cuando va él, no.

So yo is possible, but not necessary in the original sentence.

Yes, exactly.

Se me hace más corto does not mean the train journey actually takes less time. It means it feels shorter.

That is why this structure is so useful in Spanish. It expresses a subjective impression:

• La película se me hizo corta = the film felt short
• La reunión se me hizo larga = the meeting felt long

So in your sentence, the idea is that being with the speaker’s sister makes the journey seem shorter.