So + adj + uncountable noun or plural noun there is（）much traffic that maybe i cannot get to school on time.

So + adj + uncountable noun or plural noun there is（）much traffic that maybe i cannot get to school on time.

Hello! There is such a structure. For example: so large apples is also used in this topic

Can adj + be added in the middle of so that?
Why are there so many students that XXX

There are so many students that quite of the cafeteria runs out of food

Is so + adj + A + noun interchangeable with such + A + adj + noun?

Yes,
so pretty a girl = such a pretty girl
Remember, so modifies adjectives and such modifies nouns
Let's abbreviate them separately
So pretty, such a girl
The two emphasize the difference
But it's interchangeable
On uncountable nouns
so hot milk = such hot milk
Here, the article is omitted, the usage is the same
Don't worry, my explanation is absolutely correct