ibeon gyotongsagoui pihaega saenggakboda keosseoyo.

이번 means this time, this instance, or this recent one.

In 이번 교통사고, it means this traffic accident / this recent traffic accident.

A useful nuance:

• 이 = this
• 번 = occurrence, time, instance

So 이번 is often used for something happening on this occasion or in this case, not just something physically near the speaker.

Examples:

• 이번 시험 = this exam
• 이번 주 = this week
• 이번 사고 = this accident / this incident

의 shows a relationship between two nouns. Here it is similar to of in English:

• 교통사고 = traffic accident
• 피해 = damage, harm, losses
• 교통사고의 피해 = the damage/harm from the traffic accident

So this is not just literal possession. It is more like:

• damage caused by the accident
• the accident’s damage/impact

In natural English, we usually would not say the traffic accident’s damage, but Korean often uses 의 for this kind of noun connection.

피해 means damage, harm, loss, or injury suffered.

It is a broad word. Depending on context, it can include:

• physical damage
• financial loss
• injuries
• casualties
• overall harm caused by an event

So in this sentence, 피해가 컸어요 does not only mean that something was physically large. It means the accident had serious consequences or extensive damage.

For example:

• 태풍 피해 = damage from a typhoon
• 홍수 피해 = flood damage
• 피해를 입다 = to suffer damage/harm

Because 피해 is the thing being described by 컸어요.

The core structure is:

• 피해가 컸어요
• The damage was big/severe.

So 가 marks 피해 as the grammatical subject.

You can think of the sentence like this:

• 이번 교통사고의 피해가 = as for the damage from this traffic accident
• 생각보다 컸어요 = it was bigger/more serious than expected

This is very natural in Korean because descriptive verbs like 크다 often describe the subject directly.

생각보다 means than I thought, than one thought, or more naturally than expected.

It is made from:

• 생각 = thought
• 보다 = than

So literally it is something like than thought, but in natural English it usually becomes:

• more than expected
• bigger than expected
• worse than I thought

In this sentence:

• 생각보다 컸어요 = It was bigger/more serious than expected

This expression is extremely common:

• 생각보다 어려워요. = It’s harder than I thought.
• 생각보다 맛있어요. = It’s tastier than I expected.
• 생각보다 멀어요. = It’s farther than I thought.

컸어요 is the past polite form of 크다 (to be big).

Formation:

• 크다
• → 커요 (present polite)
• → 컸어요 (past polite)

So:

• 크다 = to be big / large
• 컸어요 = was big

In this sentence, 크다 does not only mean physical size. It often means:

• great
• severe
• serious
• extensive

So 피해가 컸어요 means:

• the damage was serious
• the damage was extensive
• the impact was greater than expected

Yes, if translated too literally, the damage was big can sound a little unnatural in English. But in Korean, 크다 is very commonly used with things like:

• 피해가 크다 = the damage is great/severe
• 영향이 크다 = the influence is large/significant
• 차이가 크다 = the difference is big
• 충격이 크다 = the shock is great

So 크다 often expresses degree or severity, not just physical size.

That is why a natural English translation here is usually:

• The damage from this traffic accident was greater than expected.
• The impact of this traffic accident was more serious than expected.

Because it is talking about the result or extent of a specific accident, viewed as a completed situation.

• 컸어요 = was big / turned out to be serious

Korean often uses the past tense when reporting what was found or how something turned out in a past event.

Compare:

• 피해가 커요. = The damage is big/serious.
  (more general or present-state sounding)
• 피해가 컸어요. = The damage was big/serious.
  (reporting on that accident/event)

So the past tense fits naturally when discussing a particular accident that already happened.

Yes, potentially.

피해 is broad enough to cover different kinds of harm:

• human injuries
• deaths/casualties
• property damage
• economic loss

So depending on context, the sentence may suggest:

• there were more injuries/casualties than expected
• the physical/economic damage was worse than expected
• the overall harm was more serious than expected

If Korean specifically wanted to focus only on casualties, it might use more specific words such as:

• 사상자 = casualties
• 부상자 = injured people
• 재산 피해 = property damage

But 피해 leaves it broad.

Yes, absolutely. That is usually the most natural way to understand it.

Even though 컸어요 literally comes from to be big, English often prefers:

• The damage was worse than expected
• The damage was more serious than expected
• The impact was greater than expected

So when learning this sentence, it is better to focus on the meaning and collocation:

• 피해가 크다 = damage is severe/extensive

rather than translating each word too literally.

Yes, but the nuance would change.

The original:

• 이번 교통사고의 피해가 생각보다 컸어요.

This simply presents the damage as the subject of description.

If you say:

• 이번 교통사고의 피해는 생각보다 컸어요.

Then 는 gives more of a topic or contrast feeling, something like:

• As for the damage from this traffic accident, it was greater than expected.

That version is also possible, especially if you are comparing it with something else, such as:

• injuries vs. property damage
• this accident vs. another accident
• what people expected vs. what actually happened

So 가 is a neutral, straightforward choice here.