Kablo güzergâhı topraklama hattıyla birlikte gösterildi.

Because kablo güzergâhı is a very common Turkish noun-compound pattern: Noun + Noun-(s)I.

Here:

• kablo = cable
• güzergâhı = route/path, with the compound ending -ı

So kablo güzergâhı means cable route or route of the cable.

This same pattern appears in phrases like:

• otobüs durağı = bus stop
• su borusu = water pipe
• telefon hattı = telephone line

So the -ı here is part of the compound, not just an extra ending added randomly.

No. That is a very common learner confusion.

In this sentence, the -ı in güzergâhı is the compound marker, not the accusative case.

A useful test is this:

• kablo güzergâhı = the cable route
• kablo güzergâhını = the cable route (as a definite direct object)

So if this sentence were active and the cable route were the object, you would expect kablo güzergâhını.

But here the sentence is passive:

• Kablo güzergâhı ... gösterildi = The cable route ... was shown

So kablo güzergâhı is the thing being talked about, not an accusative-marked object.

It breaks down like this:

• topraklama = grounding / earthing
• hattı = line, wire, route, with the compound ending
• -yla = with, attached form of ile

So:

• topraklama hattı = grounding line / earthing line / ground wire
• topraklama hattıyla = with the grounding line

In full form, this could also be written as:

• topraklama hattı ile

But in normal Turkish, ile is very often attached to the previous word:

• hattı ile → hattıyla

Because the base phrase is not just hat. It is the compound topraklama hattı.

After that, ile is added:

• topraklama hattı ile

And in everyday written Turkish, ile often joins onto the word before it:

• hattı ile → hattıyla

The y is a buffer consonant, used because the word already ends in a vowel sound.

So:

• hattı ile and hattıyla mean the same thing
• hattıyla is simply the more compact, very common form

Yes, they overlap, but together they form a very common expression:

• ile birlikte = together with / along with

So:

• topraklama hattıyla birlikte = together with the grounding line

Using both sounds natural and often gives a slightly more explicit or formal feel.

You could say:

• Kablo güzergâhı topraklama hattıyla gösterildi.

That is also grammatical. Adding birlikte just makes the idea of together/along with clearer.

It can be broken down like this:

• göster- = show
• -il- = passive marker
• -di = past tense

So:

• gösterildi = was shown

This passive is very common in technical, formal, and written Turkish, especially when the person doing the action is not important or not mentioned.

So the sentence focuses on the result:

• The cable route was shown... rather than
• Someone showed the cable route...

Because Turkish normally prefers verb-final word order.

A neutral structure is often:

• topic/subject first
• other information next
• verb last

So here:

• Kablo güzergâhı = topic / thing being discussed
• topraklama hattıyla birlikte = accompanying information
• gösterildi = verb

This is very natural Turkish word order, especially in formal or technical writing.

There is no separate word for the in Turkish.

Turkish does not have a definite article like English the. Whether something is understood as a or the usually comes from context, structure, and meaning.

In a sentence like this, English naturally uses the:

• The cable route was shown together with the grounding line.

But Turkish simply says:

• Kablo güzergâhı topraklama hattıyla birlikte gösterildi.

They are not the same.

• ve = and
• ile birlikte = together with / along with

So ile birlikte shows accompaniment, not simple coordination.

For example:

• Ali ve Ayşe geldi = Ali and Ayşe came
• Ali, Ayşe ile birlikte geldi = Ali came together with Ayşe

In your sentence, the idea is that the cable route was shown in combination with the grounding line, not just that two separate things are listed.

The word is traditionally spelled güzergâh, with â.

In modern Turkish, the circumflex can indicate things like:

• a historically long vowel
• a difference in pronunciation
• a more standard/formal spelling in certain words

In everyday typing, many people may write güzergah without the circumflex, but in formal writing you will often still see güzergâh.

So:

• güzergâhı is the careful standard spelling
• güzergahı may also appear in less careful writing

An active version could be:

• Kablo güzergâhını topraklama hattıyla birlikte gösterdiler.
• They showed the cable route together with the grounding line.

Notice the change:

• passive: kablo güzergâhı ... gösterildi
• active: kablo güzergâhını ... gösterdiler

In the active sentence, the whole compound takes the accusative:

• güzergâhı → güzergâhını

That is another good way to see that the -ı in güzergâhı is not itself the accusative ending.