Learn Hardcore Indonesian: Sopir diminta putar balik karena rambu menunjukkan jalan ditutup. - The driver was asked to make a U-turn because the sign shows the road is closed.

Yes, diminta is the passive form of meminta “to request/ask.” It literally means “was asked/requested.” The agent (who asked) is omitted; Indonesian often drops it when it’s obvious or unimportant (e.g., police/officials). You can add it with oleh:

Sopir diminta putar balik oleh polisi. = The driver was asked to turn back by the police.

Why is there no untuk before putar balik? Should it be “diminta untuk putar balik”?

Both are correct. With verbs of request, permission, advice, etc., untuk before the following verb is optional:

Sopir diminta putar balik.
Sopir diminta untuk putar balik. Using untuk often sounds a bit more formal or explicit; dropping it is very common in news and signs.

Is putar balik a verb? How else can I say “make a U-turn”?

Putar balik is a common verbal expression meaning “to make a U-turn/turn back.” Alternatives:

balik arah = reverse direction (very common in traffic context)
putar arah = turn around/change direction
More formal/explicit: memutar balik kendaraannya = turn the vehicle around.

Could I use disuruh instead of diminta? What’s the nuance?

diminta = “requested/asked,” more polite/neutral.
disuruh = “told/ordered,” stronger and more authoritative. In official announcements, diminta is preferred for a polite tone: Sopir diminta putar balik. If an officer is giving a direct order, disuruh would fit: Sopir disuruh putar balik.

Does rambu mean “traffic sign”? Do I need to say rambu lalu lintas?

Rambu by itself commonly means a (traffic) sign in context. Rambu lalu lintas is the full phrase “traffic sign(s),” used when you want to be explicit. Tanda is a generic “sign/symbol,” less specific to traffic.

Should I add bahwa after menunjukkan? Is rambu menunjukkan jalan ditutup okay?

Both are acceptable:

rambu menunjukkan (bahwa) jalan ditutup Adding bahwa makes the clause boundary crystal clear and sounds a bit more formal. Without bahwa is common and still clear here because of the passive clause “jalan ditutup.”

What’s the difference between ditutup, tertutup, and tutup in this context?

ditutup (passive verb): “is/was closed (by someone/authority).” Implies an action/decision. Common on signs: “Jalan Ditutup.”
tertutup (stative): “is closed/shut/covered.” Emphasizes state, not the actor: Jalan tertutup.
tutup (adjective/verb base): colloquial as predicate in signs/announcements: Jalan tutup (elliptical for “is closed”).

Why not jalannya ditutup or jalan itu ditutup? How do I show definiteness?

Indonesian doesn’t require an article. jalan ditutup already works as “the road is closed.” To be more specific/definite:

jalan itu/jalan tersebut ditutup = that/that particular road is closed.
jalannya ditutup can also mean “the road (in question) is closed,” but -nya often implies “its/the” and relies on prior context.

Can diminta mean “asked for,” like “the driver was asked for his license”? Is there ambiguity?

Yes, meminta/diminta can mean “ask for [something].” To avoid ambiguity and sound natural:

Sopir diminta menunjukkan SIM-nya. = The driver was asked to show his license. You do see “Sopir diminta SIM-nya” in casual use, but adding a verb like menunjukkan or using dimintai (e.g., Sopir dimintai keterangan) is clearer and more idiomatic.

Is the word order with karena okay? Could I put the reason first?

Yes. Current order is fine: main clause + karena-clause. You can also front the reason (add a comma):

Karena rambu menunjukkan (bahwa) jalan ditutup, sopir diminta putar balik.

Is rambu menunjukkan the best verb choice, or should I use menandakan?

Both work:

menunjukkan = “show/indicate” (very common, slightly more neutral).
menandakan = “indicate/signify” (fits well with signs/indicators). Examples: rambu menunjukkan/menandakan (bahwa) jalan ditutup.

Is berputar balik correct?

It’s understandable but uncommon. More natural options:

balik arah (very common)
putar balik
berbalik arah (also good) If you want a transitive form (explicitly turning the vehicle), use memutar balik (kendaraannya).

Why is there no comma before karena?

Indonesian doesn’t require a comma before karena when the reason clause comes after the main clause. You use a comma when the karena-clause is placed first:

Karena …, main clause.

Is supir an acceptable spelling?

The recommended, standard spelling is sopir. You’ll see supir in informal writing, but sopir is the form used in dictionaries and formal contexts.

Could I add sudah/telah to indicate the road is already closed?

Yes, to stress completion/result:

rambu menunjukkan (bahwa) jalan sudah/telah ditutup. This emphasizes that the closure has already taken effect.