Dolmuş durağı çok kalabalık olunca, ben yürümeyi tercih ediyorum.

This is because Turkish often uses a noun compound where English would use X stop or stop for X.

• dolmuş = shared minibus
• durak = stop
• dolmuş durağı = dolmuş stop / the stop for dolmuşes

In this type of compound, the second noun usually takes the 3rd person possessive suffix:

• otobüs durağı = bus stop
• tramvay durağı = tram stop
• taksi durağı = taxi stand

So durak becomes durağı here. This does not necessarily mean his/her stop in this sentence; it is just the normal compound pattern.

Dolmuş is a very common Turkish word for a type of shared minibus or shared taxi that follows a route. It is a cultural vocabulary item, so learners often notice it quickly.

In this sentence, dolmuş durağı means the place where people wait for that vehicle.

Kalabalık can function as both a noun and an adjective, and here it behaves like an adjective meaning crowded.

So:

• Dolmuş durağı çok kalabalık = The dolmuş stop is very crowded.

Turkish often uses adjectives directly after the subject, without needing a separate word like English crowded place. The structure is very natural.

Olunca comes from the verb olmak (to be, to become, to happen) plus the suffix -ınca / -ince / -unca / -ünce.

Here it means something like:

• when it is
• when it becomes
• since it is
• whenever it is

So:

• Dolmuş durağı çok kalabalık olunca = When/whenever the dolmuş stop is very crowded

The exact English translation depends on context, but the basic idea is that this first clause gives the condition or situation that leads to the speaker’s choice.

You can say two separate clauses, but olunca connects them more clearly and naturally.

Compare:

• Dolmuş durağı çok kalabalık olunca, ben yürümeyi tercih ediyorum.
  = When/if the stop is crowded, I prefer to walk.

• Dolmuş durağı çok kalabalık, ben yürümeyi tercih ediyorum.
  = The stop is crowded; I prefer to walk.

The version with olunca shows a stronger cause/time relationship between the two parts. It tells us that the crowdedness is the reason or trigger for the preference.

Yes, Turkish often drops subject pronouns because the verb ending already shows the person.

So tercih ediyorum already means I prefer.

That means this sentence could also be:

• Dolmuş durağı çok kalabalık olunca, yürümeyi tercih ediyorum.

The pronoun ben is optional here. It may be used for:

• emphasis
• contrast
• clarity in context

So ben adds a slight sense of as for me, I prefer walking.

This is a very common question. The verb tercih etmek usually takes its object in a noun-like form, and here that object is walking.

• yürümek = to walk / walking as a dictionary form
• yürümeyi = walking, as a definite direct object

Breakdown:

• yürü- = walk
• -me is part of the infinitive base here
• -y- = buffer consonant
• -i = accusative case

So yürümeyi tercih ediyorum literally means something like I prefer the act of walking.

This pattern is very common:

• yüzmeyi seviyorum = I like swimming
• kitap okumayı tercih ederim = I prefer reading books

Turkish has many expressions made from a noun + etmek.
Tercih is a noun of Arabic origin meaning preference/choice, and tercih etmek means to prefer / to choose.

This pattern is very common in Turkish:

• yardım etmek = to help
• kontrol etmek = to check
• fark etmek = to notice
• tercih etmek = to prefer

So ediyorum is the conjugated part of the expression.

Ediyorum is in the present continuous form (-iyor), but in Turkish this form is often used not only for actions happening right now, but also for current habits or general personal tendencies.

So here it likely means:

• I prefer to walk
• I tend to walk
• I usually choose to walk

It does not necessarily mean the speaker is literally making the choice at this exact moment.

Yes, and the nuance changes slightly.

• tercih ediyorum often sounds like a current, real-life habit or tendency
• tercih ederim can sound a bit more general, habitual, or sometimes stylistically neutral/formal

So both are possible, but:

• Dolmuş durağı çok kalabalık olunca, yürümeyi tercih ediyorum.
  = When the stop is crowded, I prefer to walk.

• Dolmuş durağı çok kalabalık olunca, yürümeyi tercih ederim.
  = When the stop is crowded, I prefer to walk / I would prefer to walk.

The first one often feels a little more immediate and conversational.

Çok here means very.

So:

• kalabalık = crowded
• çok kalabalık = very crowded

This is another place where Turkish is simple and direct: çok can intensify adjectives without any extra changes.

Examples:

• çok güzel = very beautiful
• çok pahalı = very expensive
• çok kalabalık = very crowded

Turkish very often puts the time/condition/reason clause first, especially with forms like olunca.

So this order is very natural:

• Dolmuş durağı çok kalabalık olunca, ben yürümeyi tercih ediyorum.

It sets up the situation first, then gives the result.

You could also reverse the order in some contexts, but the given version is more typical and smoother for everyday Turkish.

The comma is helpful, but in informal writing Turkish punctuation can be somewhat flexible.

Here the comma separates:

• the dependent clause: Dolmuş durağı çok kalabalık olunca
• the main clause: ben yürümeyi tercih ediyorum

So the comma improves readability, especially for learners, but the grammar itself does not depend on it.

Yes. In real usage, -ınca/-ince can sometimes feel like when, once, if, or since/because, depending on context.

In this sentence, English might naturally interpret it as:

• When the dolmuş stop is very crowded, I prefer to walk.
• If the dolmuş stop is very crowded, I prefer to walk.
• Since the dolmuş stop gets very crowded, I prefer to walk.

So the form itself is broad enough to cover both time and cause-like meanings. Context tells you which English phrasing sounds best.