Büyük şehirde ulaşım sorunu var.

Şehirde means in the city or at the city depending on context.

The ending -de is the locative case suffix. It shows location and often corresponds to English in, on, at.

• şehir = city
• şehirde = in the city

In Turkish, case endings are attached directly to the noun, so it is written as one word.

This suffix changes form because of two sound rules:

1. Vowel harmony decides between -de / -te and -da / -ta
   The last vowel of şehir is i, which is a front vowel, so the suffix uses e:

   • şehir + de

2. Consonant harmony decides between d and t
   Since şehir ends in r, which is a voiced consonant, the suffix uses d, not t.

So:

• şehirde = correct

Because Turkish adjectives normally come before the noun they describe, just like in English.

• büyük şehir = big city

Also, Turkish adjectives do not change form for singular/plural or for gender. So büyük stays büyük no matter what noun follows it.

Turkish does not have articles like English a/an and the.

So büyük şehirde can mean:

• in a big city
• in the big city

The exact meaning depends on context.

That is very normal in Turkish. The language often leaves definiteness unstated unless something else in the sentence makes it clear.

Because ulaşım sorunu is a very common Turkish noun-compound pattern.

• ulaşım = transportation
• sorun = problem
• ulaşım sorunu = transportation problem

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

• ulaşım sorunu
• literally something like its transportation problem
• but in real usage it simply means transportation problem

This is not usually translated as a possessive phrase in English. It is just how Turkish builds many noun combinations.

Similar examples:

• trafik sorunu = traffic problem
• su şişesi = water bottle
• okul müdürü = school principal

Here, no.

It may look like the accusative because the form is the same, but in this sentence sorunu is part of the noun compound ulaşım sorunu.

Why we know it is not accusative:

• var is not a transitive verb taking a direct object in the usual way
• the phrase ulaşım sorunu is a fixed noun phrase meaning transportation problem

A useful comparison:

• Büyük şehirde ulaşım sorunu var.
  = There is a transportation problem in the big city.

• Ulaşım sorununu çözdük.
  = We solved the transportation problem.

In the second sentence, sorununu really is accusative, because it is the direct object of çözdük.

Var means there is, there exists, or sometimes has depending on the structure.

In this sentence:

• Büyük şehirde ulaşım sorunu var.
• = There is a transportation problem in the big city.

Turkish often uses var and yok to talk about existence:

• var = there is / there are
• yok = there is not / there are not

So this sentence is an existence sentence, not a standard action sentence.

Because Turkish does not always use an explicit verb like English is in the present tense.

In many noun-based statements, Turkish simply puts the elements together, or uses words like var and yok when talking about existence.

So instead of saying something like there is with a normal verb, Turkish often uses:

• var = exists / there is
• yok = does not exist / there is not

That is why var is enough here.

A very literal breakdown is:

• büyük = big
• şehirde = in the city
• ulaşım sorunu = transportation problem
• var = exists / there is

So the sentence is roughly:

• In the big city, a transportation problem exists.

That sounds unnatural in English, but it helps show how Turkish builds the meaning.

Yes, Turkish word order is more flexible than English, but some orders sound more natural than others.

This version:

• Büyük şehirde ulaşım sorunu var.

is natural and neutral.

It puts the location first, then the thing that exists, and ends with var, which is very common in Turkish existential sentences.

Other word orders are possible, but they may sound more marked, more literary, or more focused on a particular part of the sentence.

These are important for English speakers:

• ü: a front rounded vowel, similar to German ü or French u
  It does not exist naturally in standard English.

• ş: pronounced like English sh

• ı: a vowel with no exact English equivalent
  It is not the same as i. It is a deeper, more central/back sound.

So in this sentence:

• büyük has ü
• şehirde has ş
• ulaşım has ş and ı

Getting i and ı, and u and ü, clearly separated is very important in Turkish because they can change meanings.