asa ha kaisoku yori kakuekiteisya no hou ga suite irukoto ga arimasu.

は marks 朝 as the topic: as for the morning / in the morning.

So 朝は sets the scene for the whole sentence:

• As for the morning, ...
• In the morning, ...

If you used 朝に, that would mark morning more directly as a time point, but in this sentence は sounds natural because the speaker is contrasting or describing what happens in the morning as a general tendency.

• 快速 = rapid train / quick service
  It skips some stations.
• 各駅停車 = local train / train that stops at every station

Breaking down 各駅停車:

• 各駅 = each station / every station
• 停車 = stopping

So 各駅停車 literally means a train that stops at every station.

This is a very common comparison pattern:

• A より B のほうが ...
  = B is more ... than A

In this sentence:

• 快速より = than rapid trains
• 各駅停車のほうが = local trains are more ...

So:

• 快速より各駅停車のほうが空いている = Local trains are less crowded than rapid trains

Even though English often says less crowded, Japanese uses more open/emptier:

• 空いている = uncrowded / not full / emptier

In the pattern A より B のほうが, the のほう is part of the grammar.

Here, ほう means something like side or option.
So 各駅停車のほう literally means the local-train side / the local-train option.

That is why you get:

• 快速より各駅停車のほうが...

You should think of のほうが as a set phrase in comparisons, not as something you need to translate word-for-word every time.

The が marks the thing being described by the adjective.

In:

• 各駅停車のほうが空いている

the part 各駅停車のほう is the thing that is 空いている.

So:

• 各駅停車のほうが = the local-train option is the one that...
• 空いている = is less crowded

This is why が appears there.

空く is the dictionary form of the verb, meaning to become empty / to open up / to be less crowded.

空いている describes the resulting state:

• is empty
• is open
• is less crowded

In train context, 空いている usually means:

• not crowded
• less crowded
• has more space

So here it does not mean the train is completely empty. It means there are times when the local train is less packed.

Here, ～ことがあります means:

• there are times when ...
• sometimes ...
• it may happen that ...

So:

• 空いていることがあります = there are times when it is less crowded = it is sometimes less crowded

This use of ことがあります expresses that something happens occasionally, not always.

They are doing different jobs.

1. 各駅停車のほうが

This が marks what is being compared and described:

• the local train is less crowded

2. 空いていることがあります

This が is part of the pattern ことがあります:

• there are times when ...

So the two が particles are not a mistake. They belong to different parts of the sentence.

If you say just:

• 朝は快速より各駅停車のほうが空いています it sounds like a more direct statement:
• In the morning, local trains are less crowded than rapid trains.

But the original sentence is softer and less absolute:

• 朝は快速より各駅停車のほうが空いていることがあります
• There are times when local trains are less crowded than rapid trains in the morning.

So ことがあります adds the meaning of sometimes / on some occasions.

Yes, effectively.

Japanese often omits words that are obvious from context. Here, both 快速 and 各駅停車 refer to types of trains, so something like 電車 is understood.

So the comparison is really between:

• 快速（電車）
• 各駅停車（電車）

English usually has to say rapid trains and local trains, but Japanese can leave 電車 unstated.

It depends on context.

空いている can mean:

• empty
• vacant
• available
• not crowded

Examples:

• 席が空いている = the seat is empty / available
• 店が空いている = the shop is open or not crowded, depending on context
• 電車が空いている = the train is not crowded

In this sentence, because it is talking about train types in the morning, 空いている means less crowded / not as packed.

No. The phrase ～ことがあります specifically prevents that strong meaning.

It means:

• sometimes
• there are cases when
• it can happen that

So the sentence is saying:

• In the morning, local trains can sometimes be less crowded than rapid trains.

It is an observation, not a universal rule.

Japanese and English organize this idea differently.

Japanese order:

• As for mornings, than rapid trains, local trains, more, are less crowded, there are times when

Natural English:

• In the morning, local trains are sometimes less crowded than rapid trains.

So when reading Japanese, it helps to group it like this:

• 朝は = in the morning
• 快速より = than rapid trains
• 各駅停車のほうが = local trains
• 空いている = are less crowded
• ことがあります = sometimes / there are times when

That makes the sentence much easier to follow.