Learn Hardcore Korean: dahaengida, beoseureul an nohchyeoseo jesigane dochakhaesseo. - Thank goodness, I didn’t miss the bus and arrived on time.

다행이다: “It’s a relief / That’s fortunate.” Neutral plain exclamation; common even in casual talk.
다행이에요: Polite.
다행입니다: Formal-polite.
다행이야: Intimate casual.
다행히: Adverb “fortunately,” used before a clause (e.g., 다행히 버스를 안 놓쳤어). Don’t say “다행히다.”
Intensifier: 천만다행이다 (“what a huge relief”).

Why is "다행이다" in present tense while "도착했어" is past?

Korean states your current evaluation in the present: “It is a relief” about a past result (“arrived”). This mix is natural: present feeling + past event.

Is the comma after "다행이다" natural? Could it be a period?

Yes; it marks a pause. Many would simply use a period: 다행이다. 버스를 안 놓쳐서 제시간에 도착했어. Both are fine.

Why is "버스를" marked with -를/을? Can I drop it?

놓치다 is transitive (“to miss”), so the missed thing takes -를/을: 버스를 놓치다. In casual speech you can omit it: 버스 안 놓쳐서… (still natural).

"안 놓쳐서" vs "놓치지 않아서" — what’s the difference?

Same meaning. 안 + verb is shorter and more colloquial. -지 않아서 is slightly more formal/emphatic. Either works here.

Why use "-서" (놓쳐서)? Could I use "-니까," "-기 때문에," or "-고"?

-아서/어서: natural cause → result (“so/and therefore”).
-니까: also “because,” a bit more explicit/insistent.
-기 때문에: formal/explanatory.
-고: simply “and”; 안 놓치고 도착했어 lists events rather than highlighting causality. All are possible; nuance shifts from natural consequence (-서) to explicit reasoning (-니까/-기 때문에).

How did "놓치어서" become "놓쳐서"?

Regular contraction: stem ending in ㅣ + 어서 → 여서. 놓치-어서 → 놓치어서 → 놓쳐서.

Can I say "못 놓쳐서" instead of "안 놓쳐서"?

No. 못 = “cannot/unable to.” 못 놓쳤다 means “I couldn’t miss it (even if I wanted to),” which is odd. Use 안 놓쳤다 for “didn’t miss.” If inability is intended, change the verb: 버스를 못 탔어 (“couldn’t get on the bus”).

What does "제시간에" mean, and are there alternatives?

제시간 = “the proper/scheduled time”; -에 = “at.” Alternatives:

정시에 (“on the dot,” more formal/schedule-focused)
시간 맞춰 (colloquial “on time/as scheduled”)

Does "도착하다" need a particle? Why "제시간에 도착했어"?

도착하다 is intransitive. With places you use -에 (e.g., 학교에 도착했어). Here 제시간에 uses -에 as “at (that time).”

Are the politeness levels consistent? How do I say this politely or formally?

The original is casual. Polite: 다행이에요. 버스를 안 놓쳐서 제시간에 도착했어요. Formal: 다행입니다. 버스를 놓치지 않아서 제시간에 도착했습니다. Honorific for the subject: 도착하셨어요/도착하셨습니다.

Could I replace "다행이다" with "다행히"?

Yes, with restructuring: 다행히 버스를 안 놓쳐서 제시간에 도착했어. 다행히 is an adverb; 다행이다 is a standalone evaluation.

Is the word order fixed? Can the reason come after the result?

Korean prefers reason first: …안 놓쳐서 제시간에 도착했어. Putting it after is possible but less natural; a clearer afterthought uses 왜냐하면/-거든: 제시간에 도착했어. 왜냐하면 버스를 안 놓쳤거든.

Any nuance differences among "버스를 놓치다," "버스를 못 탔어," and "정거장을 지나쳤어"?

버스를 놓치다: missed the bus (it left before you boarded).
버스를 못 탔어: couldn’t get on (reason unspecified).
정거장을 지나쳤어: passed the stop (stayed on too long/went past); not a substitute for “missed the bus.”

Pronunciation tips for tricky parts?

놓쳐서 → roughly “no-cheo-seo” (the ㅎ isn’t pronounced separately).
다행이다 → “da-haeng-i-da.”
제시간에 → “je-si-gan-e.” Say it smoothly: 다행이다, 버스를 안 놓쳐서 제시간에 도착했어.

Is "제시간에" written as one word or two?

Write it as one word: 제시간(에). You may see 제 시간 informally, but 제시간 is the standard form meaning “the proper time.”