الجسر أعلى من الطريق.

A careful MSA pronunciation is:

al-jisru aʿlā mina ṭ-ṭarīqi

A few notes:

• الجسر = al-jisr(u)
• أعلى = aʿlā
  
  • The ʿ stands for the Arabic letter ع, a throat sound that English does not have.
• من is basically min, but before الـ it is often pronounced mina for ease.
• الطريق is pronounced aṭ-ṭarīq(i), not al-ṭarīq, because ط is a sun letter, so the l of الـ assimilates.

In normal pausal reading, many speakers drop the final short case vowels.

Because in Arabic, the present tense of to be is usually not expressed in simple sentences like this.

So:

• الجسر أعلى من الطريق = The bridge is higher than the road

There is no separate word for is. This is completely normal in Arabic.

If you wanted the past, then Arabic would use a verb such as كان:

• كان الجسر أعلى من الطريق = The bridge was higher than the road

This is a nominal sentence.

Its structure is:

• الجسر = the subject/topic
• أعلى من الطريق = the predicate/comment about the subject

So literally, the pattern is:

the bridge + higher than the road

This is one of the most common sentence types in Arabic.

أعلى is an elative form, often called the Arabic comparative/superlative form.

Here, because it is followed by من, it means higher:

• أعلى من = higher than

So in this sentence:

• الجسر أعلى من الطريق = The bridge is higher than the road

The same word أعلى can also mean highest in other contexts, but with من it is clearly comparative: higher than.

Yes. In comparisons, من is the normal word used for than.

So:

• أعلى من الطريق = higher than the road
• أكبر من = bigger than
• أسرع من = faster than

This is one place where من does not translate as its basic meaning from, even though that is its usual dictionary meaning.

Because the sentence is talking about the bridge and the road, not just any bridge and any road.

• الجسر = the bridge
• الطريق = the road

Arabic can compare definite nouns with no problem:

• البيت أكبر من المدرسة = The house is bigger than the school
• هذا الجسر أعلى من ذلك الطريق = This bridge is higher than that road

So having الـ on both nouns is perfectly normal.

Because عالٍ and أعلى do different jobs.

• عالٍ = high
• أعلى = higher / highest

Compare:

• الجسر عالٍ = The bridge is high
• الجسر أعلى من الطريق = The bridge is higher than the road

So if you want a comparison, you normally need the elative form أعلى, not the basic adjective عالٍ.

In this kind of comparative structure, أعلى normally stays in the masculine singular form.

That is a very important rule.

When the elative is used in the pattern:

أفعل + من

it usually does not change to match gender or number.

For example:

• السيارة أسرع من الحافلة = The car is faster than the bus
• السيارات أسرع من الحافلة = The cars are faster than the bus
• البنت أكبر من أخيها = The girl is older/bigger than her brother

So even if the thing being described is feminine or plural, the comparative form often remains like أعلى, أكبر, أسرع, etc.

The fully vocalized form is:

الجِسْرُ أَعْلَى مِنَ الطَّرِيقِ

Here is what is happening:

• الجسرُ is nominative because it is the subject of the nominal sentence.
• أعلى is also nominative as the predicate, but its case ending is not visibly shown because it ends in ى.
• الطريقِ is genitive because it comes after the preposition من.

So even if you do not hear every ending in normal speech, the grammatical analysis is still there.

This is a very common question.

• أعلى من expresses a comparison
• فوق expresses position/location

So:

• الجسر أعلى من الطريق = The bridge is higher than the road
• الجسر فوق الطريق = The bridge is above the road / over the road

These are related ideas, but they are not identical.

A bridge might be above a road physically, and therefore also higher than it, but the grammar is different:

• أعلى من = comparative
• فوق = preposition of place

It can mean both, depending on the structure.

With من, it means higher than:

• الجسر أعلى من الطريق = The bridge is higher than the road

Without من, and depending on context, it can have a superlative sense such as highest:

• هذا أعلى جبل = This is the highest mountain
• الجبل الأعلى = the highest mountain / the higher mountain, depending on context

So in your sentence, because of من الطريق, the meaning is clearly higher, not highest.