في حال حادث مروري، يوثق السائق الآخر موقع الحادث.

في حال is a common formal expression meaning in the event of, in case of, or if there is.

• في = in
• حال literally means state or condition

But together, في حال often works like a set phrase rather than being translated word-for-word.

So in this sentence, it introduces the situation under which the action happens.

A fully vocalized version would be:

فِي حالِ حادثٍ مُروريٍّ، يُوَثِّقُ السّائِقُ الآخَرُ مَوقِعَ الحادِثِ.

This helps show the grammar more clearly:

• حالِ: genitive after في
• حادثٍ: genitive
• مروريٍّ: adjective matching حادثٍ
• يُوَثِّقُ: verb
• السائقُ الآخرُ: subject, nominative
• موقعَ: direct object, accusative
• الحادثِ: genitive because it is the second part of an iḍāfa phrase

In normal Arabic writing, these short vowels are usually omitted.

Because Arabic adjectives normally come after the noun they describe.

So:

• حادث = accident
• مروري = traffic-related

Together, حادث مروري means traffic accident.

Also, the adjective must agree with the noun in:

• gender
• number
• definiteness
• case

Here both are singular, masculine, indefinite, and genitive.

مروري is a nisba adjective, meaning an adjective formed from a noun to mean related to that noun.

It comes from مرور, which is related to passing / traffic.

So:

• مرور = traffic
• مروري = traffic-related

That is why حادث مروري means a traffic accident.

يوثق is the imperfect form of the verb وثّق.

• past: وثّق = documented
• imperfect: يوثّق = documents / is documenting

In this kind of formal or procedural sentence, the imperfect often has a general or instructional sense. So it can mean something like:

• documents
• is to document
• should document
  depending on context

So even though it is grammatically the imperfect, its meaning in official language can feel like an instruction.

Because verb-first order is very common in Modern Standard Arabic.

This sentence uses:

• يوثق = the verb
• السائق الآخر = the subject
• موقع الحادث = the object

So the pattern is VSO: verb–subject–object.

You could also say:

السائق الآخر يوثق موقع الحادث

That would still be correct, but it gives the subject a bit more emphasis.

Because الآخر is an adjective describing السائق, and in Arabic adjectives must match the noun in definiteness.

So:

• السائق الآخر = the other driver
• سائق آخر = another driver

This is a very important pattern in Arabic:

• definite noun -> definite adjective
• indefinite noun -> indefinite adjective

The difference is mainly definiteness:

• آخر = another / a different
• الآخر = the other

Examples:

• سائق آخر = another driver
• السائق الآخر = the other driver

In your sentence, it is السائق الآخر because the meaning is a specific other driver, not just any other driver.

Because Arabic often expresses of using an iḍāfa construction.

Here:

• موقع = site / location
• الحادث = the accident

So:

موقع الحادث literally means site of the accident.

There is no separate word for of. Arabic simply puts the two nouns together.

A useful point:

• the first noun in an iḍāfa usually does not take ال
• the second noun determines whether the whole phrase is definite

So because الحادث is definite, موقع الحادث means the accident site, not just an accident site.

Because the first mention introduces the accident as something not yet identified:

• حادث مروري = a traffic accident

After that, the sentence refers back to that same accident:

• موقع الحادث = the site of the accident

This is similar to English:

• a traffic accident
• then later the accident site

Once the thing has been introduced, it becomes specific.

Here it is active.

• يُوَثِّقُ = he documents / he records
• passive would be يُوَثَّقُ = it is documented

So in this sentence, السائق الآخر is doing the action.

This matters because the spelling without vowel marks can sometimes look ambiguous to learners, but in context the meaning is clearly active.

It would become:

في حال حادث مروري، توثق السائقة الأخرى موقع الحادث.

The changes are:

• يوثق -> توثق because the subject is feminine singular
• السائق -> السائقة
• الآخر -> الأخرى

So Arabic shows the gender in both the noun and its adjective, and often in the verb as well.