Przez ten objazd musieliśmy zawrócić i wrócić na główną ulicę.

Here przez means because of / due to, not its more basic meaning through.

So przez ten objazd means something like:

• because of this detour
• due to this diversion

This use of przez is quite common in everyday Polish, especially in speech.

Examples:

• Przez deszcz spóźniliśmy się. = We were late because of the rain.
• Przez korki nie dojechałem na czas. = I didn’t arrive on time because of the traffic jams.

So in this sentence, it introduces the reason for what happened.

Because objazd is a masculine inanimate noun, and after przez you normally use the accusative case.

For masculine inanimate nouns, the accusative singular usually looks the same as the nominative singular:

• nominative: ten objazd
• accusative: ten objazd

So although the case changes grammatically, the form does not change here.

That is why you see:

• przez ten objazd

and not a different-looking form.

Objazd means detour, diversion, or an alternative route used when the normal road is blocked or unavailable.

It often appears on road signs. For example:

• Objazd = Detour
• Wyznaczony objazd = Marked detour

In this sentence, it suggests that because of the detour, the speakers had to change direction and get back to the main road.

Musieliśmy is the past tense of musieć (to have to / must) in the 1st person plural: we had to.

So:

• musieć = to have to
• musieliśmy = we had to

It is made from the past tense stem plus the personal ending:

• musieli-
  • -śmy

This form is used for a group that is:

• all male, or
• mixed gender

If the group were all female, it would be:

• musiałyśmy

So musieliśmy tells you both:

1. it happened in the past
2. the subject is we

Because after musieć in Polish, you normally use the infinitive of the action that had to be done.

So the structure is:

• musieć + infinitive

Examples:

• Muszę iść. = I have to go.
• Musieliśmy czekać. = We had to wait.
• Musieliśmy zawrócić. = We had to turn back.

In your sentence, there are two actions after musieliśmy:

• zawrócić
• wrócić

So literally the structure is:

• we had to turn around and return

They are related, but not the same.

• zawrócić = to turn back / turn around
• wrócić = to return / go back

In this sentence, the two verbs describe two stages:

1. zawrócić — first, they had to physically turn around
2. wrócić na główną ulicę — then, they returned to the main street

So it is not redundant. It is more like:

• we had to turn around and get back to the main road

That is a very natural sequence in Polish.

Both zawrócić and wrócić are perfective verbs here, which means they present the actions as completed, whole events.

• zawracać / zawrócić
• wracać / wrócić

In this sentence, the idea is not that they were in the middle of turning or returning, but that they had to complete those actions.

So perfective fits well:

• musieliśmy zawrócić i wrócić = we had to turn back and return

If you used imperfective forms, it would sound different and would focus more on process or repeated action, not on a single completed necessity.

Because with roads, streets, and similar places, Polish often uses na when talking about movement onto or back onto that route.

So:

• wrócić na główną ulicę = return to the main street / get back onto the main street

This is very natural in Polish, because a street is treated as a surface or route you move onto.

By contrast, do often means movement into a place or to a destination in a more general sense:

• do domu = home
• do miasta = to the city

With ulica, na is commonly the better choice when talking about getting onto the street itself.

This is the accusative singular because it follows na in a phrase of motion:

• na + accusative = movement to/onto something

The noun is:

• ulica = street

Its accusative singular is:

• ulicę

The adjective główna (main) has to agree with ulica in gender, number, and case:

• nominative: główna ulica
• accusative: główną ulicę

So:

• na główną ulicę = onto the main street

Yes, it could be phrased differently, but the original order is natural.

The sentence begins with the reason:

• Przez ten objazd... = Because of this detour...

Then it gives the result:

• musieliśmy zawrócić i wrócić na główną ulicę

You could also say:

• Musieliśmy przez ten objazd zawrócić i wrócić na główną ulicę.

But that is less natural in many contexts.

Starting with przez ten objazd is useful because it immediately sets up the cause. Polish word order is flexible, but the chosen order often shows what the speaker wants to emphasize.

Not really in this sentence.

If przez meant through, the sentence would suggest movement through the detour itself, but that does not fit well with the rest of the sentence:

• musieliśmy zawrócić i wrócić...

Here the meaning is clearly causal:

• because of this detour

Polish very often allows przez + accusative to express a negative or inconvenient cause:

• przez pogodę = because of the weather
• przez remont = because of the roadworks
• przez objazd = because of the detour

Because Polish usually does not need subject pronouns when the verb form already shows who the subject is.

Here musieliśmy already means we had to, so my (we) is unnecessary.

You could say:

• My musieliśmy zawrócić...

but that usually adds emphasis, for example:

• We had to turn back, not someone else.

In neutral sentences, Polish normally drops the pronoun.

It can suggest both, depending on context.

A very literal translation is:

• return to the main street

But in natural English, especially in a driving context, you might often say:

• get back onto the main road
• go back to the main street

That is because wrócić often implies returning to a route, place, or previous position, not just simply “coming back” in the abstract.

So in road context, get back onto is often the most natural interpretation.