Correct reading of kanji

Hi Guys,
In the following statement: Hokkaido shinkansen between new Aomori and new Hakodate

What is the correct reading of the kanji 間. is it かん、ま、あいだ ？

北海道新幹線の新青森―新函館間

ほっかいど しんかんせん しんあおもり － しんは こだて ？

That's not a statement, it's a noun phrase... but...

The correct reading is かん, because it's a suffix being attached to a kanji compound word and only かん acts as a suffix like that.

When you have 何々の間 then you have a more subtle situation where you need to use context and meaning (especially of the actual phrase in place of 何々) to understand the reading of 間.