La longa vico de veturiloj igis la policistinon paroli pli laŭte ol kutime.

The sentence follows this pattern:

subject + igi + object + infinitive

So here:

• La longa vico de veturiloj = the subject
• igis = the main verb
• la policistinon = the object
• paroli pli laŭte ol kutime = the action she was caused to do

A very common Esperanto pattern is:

X igas Y fari ion = X makes/causes Y do something

So this sentence is built in a very regular way.

Igi means to make, to cause, or to bring about.

In this sentence, igis is the past tense form, so it means made or caused.

Esperanto often uses igi to show causation:

• ridigi = to make someone laugh
• sidigi = to make someone sit
• trankviligi = to calm, to make calm

But igi can also appear as its own verb, as it does here:

• La bruo igis min foriri. = The noise made me leave.
• La novaĵo igis ŝin plori. = The news made her cry.

So igis la policistinon paroli means made the policewoman speak.

Because la policistinon is the direct object of igis.

The sentence is not saying that the policewoman is doing the main verb herself. The main verb is igis, and the thing doing that causing is la longa vico de veturiloj. The person affected by that causing is la policistinon, so she gets the accusative ending -n.

Compare:

• La hundo mordis la viron. = The dog bit the man.
• La bruo igis la viron krii. = The noise made the man shout.

In both cases, la viron is the object of the main verb.

After igi, the action that someone is caused to do is usually given in the infinitive.

So:

• igis la policistinon paroli = made the policewoman speak

Not:

• igis la policistinon parolas

That would be ungrammatical.

This is similar to English made her speak, not made her spoke.

Other examples:

• Ŝi igis min atendi. = She made me wait.
• La instruisto igis la infanojn sidi. = The teacher made the children sit.

Because laŭte is an adverb, and it describes how she spoke.

• laŭta = loud, as an adjective
• laŭte = loudly, as an adverb

Since it modifies the verb paroli, Esperanto uses the adverb ending -e:

• paroli laŭte = to speak loudly

If you used laŭta, it would need to describe a noun:

• laŭta voĉo = a loud voice
• laŭta sono = a loud sound

So in this sentence, pli laŭte means more loudly.

Pli ... ol ... is the regular Esperanto comparative pattern:

• pli = more
• ol = than

So:

• pli laŭte ol kutime = more loudly than usual

This works with adjectives, adverbs, and sometimes other expressions:

• pli granda ol = bigger than
• pli rapide ol = more quickly than
• pli bone ol = better than

It is a very direct system, much like English more ... than ....

Kutime means usually, normally, or as usual.

So pli laŭte ol kutime literally means more loudly than usually, which English expresses more naturally as more loudly than usual.

Esperanto often allows this kind of short comparison without repeating the full clause. The fuller idea would be something like:

• louder than she usually speaks

But Esperanto can simply say:

• pli laŭte ol kutime

This is very natural.

Vico means row, line, or queue, and de veturiloj tells you what the line consists of.

So:

• vico = line/queue
• de veturiloj = of vehicles

Esperanto often uses de for this kind of relationship, where English might use of or sometimes just a noun placed before another noun.

Examples:

• grupo de homoj = group of people
• glaso de akvo = glass of water
• amaso de libroj = pile of books

So la longa vico de veturiloj is a very normal way to say the long line of vehicles.

In Esperanto, adjectives agree with the nouns they describe in number and case.

Here:

• vico is singular and not accusative
• so the adjective is also singular and not accusative: longa

That is why we get:

• la longa vico

If the noun were plural, the adjective would also be plural:

• la longaj vicoj

If it were accusative, both would take -n:

• Mi vidis la longan vicon.

But in this sentence, la longa vico de veturiloj is the subject, so it does not take -n.

Policistinon can be broken down like this:

• polic- = police
• -ist- = person engaged in a profession or activity
• -in- = female
• -o = noun
• -n = accusative

So:

• policisto = police officer / policeman
• policistino = policewoman / female police officer
• policistinon = the accusative form of policistino

This is a very useful example of Esperanto word-building.

Because they are two separate noun phrases, and each one can be definite.

• la longa vico de veturiloj = the long line of vehicles
• la policistinon = the policewoman

Esperanto uses la much like English the. If both noun phrases are definite in meaning, both can take la.

There is nothing unusual about having la more than once in the same sentence.

Yes, to some extent. Esperanto word order is flexible, especially because the accusative -n helps show grammatical roles.

The neutral order here is:

• La longa vico de veturiloj igis la policistinon paroli pli laŭte ol kutime.

But other orders are possible for emphasis, such as putting the object earlier. Still, the standard order is the clearest and most natural for learners.

So while Esperanto allows flexibility, this sentence is written in a very normal, straightforward order: subject → verb → object → infinitive phrase.

Usually igi means make or cause, and it does not automatically imply physical force.

In this sentence, igis suggests that the long line of vehicles created a situation where the policewoman had to speak louder. It is more like caused than forcibly compelled.

If you want a stronger idea of forcing, Esperanto has verbs like:

• devigi = to force, compel
• trudi = to impose

So igis is a good neutral choice here: the situation caused her to speak more loudly.