ما دام الممر فارغا، ينقل عامل النقل الحمولة.

In this sentence, ما دام means as long as or so long as.

It introduces a condition that continues over a period of time:

• ما دام الممر فارغًا = as long as the corridor is empty

This is different from:

• إذا, which usually means if / when
• طالما, which can also mean as long as, but ما دام is especially common when the idea is tied to a continuing state

Grammatically, ما دام is built from the verb دام (to continue / last) together with ما. In usage, learners should usually treat ما دام as a set expression meaning as long as.

Yes. دام is a verb, and in this pattern it behaves like one of the verbs that can take a subject and a predicate, somewhat like كان and its sisters.

So in:

• ما دام الممر فارغًا

you have:

• الممر = the subject of دام
• فارغًا = its predicate

Because دام belongs to the كان-type family, its predicate is put in the accusative.

That is why you get:

• الممر → nominative
• فارغًا → accusative

Because it is the predicate of دام.

The verb دام, in this use, works like كان:

• the subject stays nominative
• the predicate becomes accusative

So:

• الممرُ = nominative subject
• فارغًا = accusative predicate

A fully vocalized version would be:

• ما دامَ الممرُّ فارغًا

This is a very common thing for learners to notice, because in English we just say the corridor is empty, but in Arabic the grammar is marking the adjective differently because of the verb pattern.

Because it is the subject of دام in the clause ما دام الممر فارغًا.

In the كان-type structure:

• the noun being described is nominative
• the description is accusative

So:

• الممرُ = the corridor/corridor-way → nominative
• فارغًا = empty → accusative

If full case endings are written, it would be:

• الممرُّ

In normal unvowelled writing, that ending is not shown.

What you see in plain script can hide the case ending.

The fully vocalized form is:

• فارغًا

Without vowel marks, Arabic often writes this simply as:

• فارغا

That final ا is the accusative tanwīn alif used with many indefinite singular nouns and adjectives.

So this is not a different word. It is still فارغ (empty), but here it is in the indefinite accusative form:

• فارغٌ = nominative
• فارغًا = accusative
• فارغٍ = genitive

The imperfect (ينقل) is used here for a present-time or habitual meaning.

Depending on context, it can mean things like:

• he transports
• he is transporting
• he carries/moves
• he does transport

In a sentence like this, it often expresses a general or repeated action under a condition:

• As long as the corridor is empty, the transport worker moves the load.

So the imperfect is natural because the sentence describes what happens whenever that condition is true.

The subject is عامل النقل.

So the main clause is:

• ينقل عامل النقل الحمولة

Literally, the verb comes first, then the subject, then the object:

• ينقل = transports/moves
• عامل النقل = the transport worker
• الحمولة = the load/cargo

This is a normal Arabic VSO pattern:

• Verb – Subject – Object

Even though ينقل by itself can mean he transports, the explicit subject is then added right after it: عامل النقل.

It is an iḍāfa construction, often called a genitive construct.

It consists of:

• عامل = worker
• النقل = transport / transportation

Together:

• عامل النقل = the transport worker or worker of transport

Important iḍāfa points:

1. The first noun (عامل) does not take ال
2. The second noun (النقل) is in the genitive
3. The whole phrase becomes definite because the second noun is definite

So although عامل has no ال, the whole phrase can still mean the transport worker.

Because it is the second noun in the iḍāfa and it is making the whole phrase definite.

Compare:

• عامل نقل = a transport worker / a worker of transport
• عامل النقل = the transport worker / the transportation worker

In an iḍāfa, definiteness is usually determined by the second noun. Since النقل is definite, the entire phrase عامل النقل is definite.

Also, because it is the second term of an iḍāfa, النقل is grammatically genitive, even if the case ending is not written in ordinary text.

الحمولة is the direct object of ينقل, because it is the thing being moved or transported.

So in:

• ينقل عامل النقل الحمولة

the structure is:

• ينقل = verb
• عامل النقل = subject
• الحمولة = direct object

The direct object in Arabic is normally accusative.

A fully vocalized form would be:

• الحمولةَ

Because the noun is definite, there is no tanwīn.

In ordinary unvowelled writing, nominative and accusative often look the same, so learners have to identify the function from sentence structure.

Because Arabic commonly uses verbal sentences, where the order is:

• Verb – Subject – Object

So:

• ينقل عامل النقل الحمولة

is a very natural Arabic order.

Arabic could also use a subject-first structure in some contexts, but verb-first is very common, especially in neutral written style.

For learners, it helps to recognize two separate parts in the full sentence:

1. ما دام الممر فارغًا = conditional/time clause
2. ينقل عامل النقل الحمولة = main verbal clause

Not in this structure.

After دام (like after كان), the predicate is usually an indefinite noun or adjective:

• الممر فارغًا = the corridor is empty

Using الفارغ here would usually not be the normal way to say it in this sentence.

So Arabic prefers:

• الممر فارغًا

rather than:

• الممر الفارغ

The form الممر الفارغ is instead a noun phrase meaning:

• the empty corridor

That is a different structure from saying:

• the corridor is empty

In careful, formal MSA, the full pronunciation would be something like:

• ما دامَ الممرُّ فارغًا، ينقلُ عاملُ النقلِ الحمولةَ.

But in less formal reading, many speakers reduce or drop some final case endings, especially in pause.

So for learning purposes:

• It is important to understand the grammar
• It is useful to practice the full endings
• But you will often hear less-than-fully-inflected pronunciation in real life

In other words, the endings matter a lot for grammar, even when they are not always fully pronounced in everyday formal speech.