kuukou he iku nara, kono kaisoku ni noreba norikae ga sukunai wake da.

Here なら sets up a condition or topic-like assumption: if you're going to the airport / if it’s a case of going to the airport.

It often sounds like the speaker is responding to an already relevant idea. So compared with a plain conditional, なら can feel like:

• If you’re going to the airport, then...
• As for getting to the airport, then...

It is less about a purely hypothetical condition and more about taking a situation as given and commenting on it.

Both へ and に can be used with 行く.

• 空港へ行く focuses a bit more on direction toward the airport.
• 空港に行く focuses a bit more on the destination.

In many everyday sentences, the difference is small, and both would be natural. Here へ is perfectly normal.

快速 is a noun referring to a rapid train or rapid service.

So この快速 means this rapid train or this rapid service.

In train-related Japanese, service types are often treated like nouns:

• 快速 = rapid
• 急行 = express
• 特急 = limited express

The verb 乗る uses に for the vehicle or thing you get on.

So:

• 電車に乗る = ride/get on the train
• バスに乗る = ride/get on the bus
• この快速に乗る = take this rapid train

This is just the normal particle pattern for 乗る.

乗れば is the -ba conditional form of 乗る.

• dictionary form: 乗る
• conditional: 乗れば

It means if you ride/take or if you get on.

So この快速に乗れば means if you take this rapid train.

Because they are doing two different jobs.

• 空港へ行くなら = if you're going to the airport
• この快速に乗れば = if you take this rapid train

So the sentence structure is basically:

• If the goal is going to the airport, then if you take this rapid train, ...

This is natural in Japanese. The first part sets the overall situation, and the second part gives the practical method within that situation.

乗り換え means a transfer or changing trains.

It comes from the verb 乗り換える, which means to transfer or to change from one train/bus/etc. to another.

In this sentence, 乗り換え is being used as a noun:

• 乗り換えが少ない = there are few transfers / you have fewer transfers

With 少ない, the thing that is few is commonly marked with が.

So:

• 人が少ない = there are few people
• 仕事が少ない = there is little work
• 乗り換えが少ない = there are few transfers

In other words, 少ない works like few / not many, and the item being described is marked with が.

わけだ adds an explanatory or logical-conclusion feeling. It is like saying:

• that means...
• so...
• it follows that...
• which is why...

So the sentence is not just stating a fact mechanically. It sounds like the speaker is drawing a conclusion from the situation.

For example, the nuance is something like:

• If you're going to the airport, then taking this rapid means you'll have fewer transfers.
• So, if the destination is the airport, this rapid is the one to take since it reduces transfers.

No. 少ない means few or not many, not none.

So 乗り換えが少ない means:

• there are few transfers
• you will have fewer transfers
• the number of transfers is small

If the speaker wanted to say no transfers, they would say something like:

• 乗り換えがない = there are no transfers

Japanese often leaves out the subject when it is obvious from context.

In this sentence, the understood subject is probably something like:

• you, if the speaker is giving advice
• or a general person, as in if one is going to the airport

So Japanese does not need to say あなたは unless there is a special reason to emphasize it. Omitting the subject is very natural here.