Dolmuş çok kalabalıksa bazen yürümeyi tercih ediyorum.

Dolmuş is a very common Turkish word for a shared minibus/taxi that follows a set route. It is a form of public transport in Turkey.

So in this sentence, dolmuş is the thing that might be crowded.

Kalabalık means crowded.

The ending -sa / -se adds the meaning if. So:

• kalabalık = crowded
• kalabalıksa = if it is crowded

Here, the sentence is saying:

• Dolmuş çok kalabalıksa... = If the dolmuş is very crowded...

The -sa/-se ending is often called the conditional ending.

This is a buffer consonant.

The base form is yürümek = to walk.
To turn it into a noun-like form that can be the object of tercih etmek, Turkish uses -me/-ma plus a case ending:

• yürüme = walking / the act of walking
• yürümeyi = walking (as a definite object)

The buffer -y- appears because Turkish usually inserts y between two vowels:

• yürüme + i → yürümeyi

This is very normal in Turkish grammar.

Because tercih etmek usually takes a noun or noun-like object, not the plain dictionary infinitive.

So Turkish says:

• yürümeyi tercih ediyorum = I prefer walking / I prefer to walk

Here is the structure:

• yürümek = to walk
• yürüme = walking
• yürümeyi = walking (object form, with accusative)

This is very common in Turkish:

• gitmeyi seviyorum = I like going / I like to go
• okumayı tercih ediyorum = I prefer reading / I prefer to read

Tercih etmek is a common Turkish compound verb.

• tercih = preference / choice
• etmek = to do / to make

Together, tercih etmek means to prefer.

In the present continuous / present habitual form:

• tercih ediyorum = I prefer / I am preferring

Many Turkish verbs are built this way with a noun + etmek:

• yardım etmek = to help
• dikkat etmek = to pay attention
• tercih etmek = to prefer

Bazen means sometimes.

In this sentence:

• Dolmuş çok kalabalıksa bazen yürümeyi tercih ediyorum.
• If the dolmuş is very crowded, I sometimes prefer to walk.

Its position is flexible, but it usually goes before the verb or before the part it modifies. Turkish word order is often more flexible than English, as long as the verb stays near the end.

For example, these are also possible depending on emphasis:

• Bazen dolmuş çok kalabalıksa yürümeyi tercih ediyorum.
• Dolmuş çok kalabalıksa yürümeyi bazen tercih ediyorum.

The original sentence sounds natural.

Because çok means very here and modifies the adjective kalabalık.

• çok kalabalık = very crowded

So:

• Dolmuş çok kalabalıksa = if the dolmuş is very crowded

Turkish usually places adverbs like çok before the adjective or verb they modify.

In form, ediyorum is the Turkish present continuous. But in real usage, this form often covers both:

• I am preferring
• I prefer
• I tend to prefer

So in this sentence, the most natural English translation is:

• I sometimes prefer to walk

Turkish very often uses the -iyor form for present-time habits and general tendencies, not only actions happening right now.

Because Turkish often expresses to be without a separate verb in the present tense.

So:

• Dolmuş kalabalık. = The dolmuş is crowded.
• Dolmuş kalabalıksa... = If the dolmuş is crowded...

The idea of is is built into the structure rather than expressed with a separate word like English is.

A useful breakdown is:

• kalabalık = crowded
• -sa = if

In practice, the meaning is:

• kalabalıksa = if it is crowded

You may also think of it as attaching the conditional ending to a predicate. Turkish often compresses ideas that English expresses with separate words.

Yürümeyi is in the accusative case.

Breakdown:

• yürüme = walking
• yürümeyi = the walking / walking (as the object)

The accusative is used because tercih etmek is taking a specific object: the act of walking.

This is very common with verbal nouns in Turkish:

• yemek yemeyi seviyorum = I like eating food
• erken kalkmayı tercih ediyorum = I prefer getting up early

Yes, that is close in meaning, but the most natural understanding is:

• If the dolmuş is very crowded, I sometimes prefer to walk.

Because bazen has scope over the main action tercih ediyorum, the idea is that this happens on some occasions.

So the sentence suggests a repeated tendency, not just one specific event.

Not completely. Turkish word order is flexible, but the neutral pattern usually puts the verb at the end.

Original:

• Dolmuş çok kalabalıksa bazen yürümeyi tercih ediyorum.

Possible alternatives:

• Bazen dolmuş çok kalabalıksa yürümeyi tercih ediyorum.
• Dolmuş çok kalabalıksa yürümeyi tercih ediyorum bazen.
  This is possible, but less neutral and more marked.

The original sentence is natural and clear. The final verb tercih ediyorum is a strong clue to the structure.

A fairly literal version would be:

• If the dolmuş is very crowded, sometimes I prefer walking.

A more natural English translation is:

• If the dolmuş is very crowded, I sometimes prefer to walk.

Turkish often uses structures that sound slightly more noun-based or compressed than natural English.