Learn Hardcore Hungarian: Ennek a környéknek olyan jó a tömegközlekedése, mint a másiknak. - Public transport in this neighbourhood is as good as in the other one.

Breakdown of Ennek a környéknek olyan jó a tömegközlekedése, mint a másiknak.

Why is it ennek a környéknek, not just ez a környék?

Because this sentence does not use this neighborhood as a plain subject. It uses it as the possessor of tömegközlekedése.

So the idea is structurally like:

ez a környék = this neighborhood
ennek a környéknek a tömegközlekedése = this neighborhood’s public transport

In Hungarian, a possessor is very often marked with -nak/-nek, so környék becomes környéknek.

Also, when a demonstrative goes with a noun, Hungarian normally uses:

So ennek a környéknek is the correct possessed/oblique form of ez a környék in this structure.

Why do both ennek and környéknek seem to show the same case?

This is a very common Hungarian pattern: when a demonstrative modifies a noun, the demonstrative usually matches the noun’s case.

Compare:

So here:

This doubling is normal Hungarian grammar, not emphasis.