Temos de fazer um desvio para evitar o trânsito.

Temos is the we form of the verb ter in the present tense.

• eu tenho = I have
• tu tens = you have
• ele/ela tem = he/she has
• nós temos = we have

In this sentence, though, temos is part of the expression ter de + infinitive, which means to have to / to need to.

So temos de fazer means we have to do or we need to do.

Because Portuguese uses the structure ter de + infinitive to express obligation or necessity.

So:

• temos de fazer = we have to do
• tenho de sair = I have to leave
• ela tem de estudar = she has to study

You cannot normally drop the de here.
Temos fazer would be incorrect.

Yes. Both are understood and used.

However, in European Portuguese, ter de + infinitive is often felt to be the more standard or typical way to express obligation:

• Temos de fazer um desvio
• Temos que fazer um desvio

Both mean the same thing in most everyday situations: we have to make/take a detour.

For a learner of Portuguese from Portugal, ter de is a very good pattern to learn and use.

Because Portuguese often omits subject pronouns when the verb ending already makes the subject clear.

Here, temos clearly shows we, so nós is not necessary.

• (Nós) temos de fazer um desvio

Both are possible, but the version without nós sounds more natural in many contexts.

You would add nós mainly for emphasis, contrast, or clarity:

• Nós temos de fazer um desvio, eles não.

Fazer um desvio means to make/take a detour.

• desvio = detour, diversion, deviation
• fazer um desvio = to go by a different route than planned

In road or travel contexts, it is a very natural expression.

So this is not a literal do a deviation in English. The natural English equivalent is take a detour or make a detour.

Yes. Desvio is a masculine noun, so it takes um in the singular indefinite form:

• um desvio = a detour
• o desvio = the detour
• desvios = detours

This is just something you have to learn with the noun.

Para + infinitive expresses purpose: to, in order to, so as to.

So:

• para evitar o trânsito = to avoid the traffic

This is a very common Portuguese structure:

• Estudo para aprender. = I study to learn.
• Saí cedo para não me atrasar. = I left early so I wouldn’t be late.

Here it tells you why they have to make the detour.

Portuguese often uses the definite article where English would not.

So o trânsito is the natural way to say traffic in this kind of sentence.

• evitar o trânsito = avoid traffic
• o trânsito está terrível = traffic is terrible

For English speakers, this can feel strange at first, because English often uses the noun without an article in a general sense. Portuguese is simply more likely to include it here.

Usually, no.

In this sentence, trânsito means traffic, especially road traffic.

That is important because an English speaker might guess from the similarity that it means transit in the sense of public transport. Normally it does not.

• trânsito = traffic
• transportes públicos = public transport

So evitar o trânsito means avoid the traffic, not avoid transit.

Because after para, Portuguese normally uses the infinitive to express purpose.

• para evitar = to avoid

The form evitando is the gerund, meaning something more like avoiding, and it does not fit naturally here to express purpose.

Compare:

• Fizemos um desvio para evitar o trânsito. = We made a detour to avoid the traffic.
• Fomos evitando o trânsito. = We kept avoiding the traffic.

So in this sentence, para evitar is the correct structure.

A careful European Portuguese pronunciation is roughly:

Temos de fazer um desvio para evitar o trânsito.

Stress falls mainly on:

• TE-mos
• fa-ZER
• des-VI-o
• e-vi-TAR
• TRÂN-si-to

A rough English-friendly approximation is:

TEH-moosh duh fuh-ZER oong duzh-VEE-oo puh-ruh ee-vee-TAR oo TRAN-see-too

A few useful notes:

• s in temos sounds like sh in European Portuguese before a consonant-like sound in connected speech.
• de is often reduced and unstressed.
• um is nasal, so it does not sound exactly like English oom or uhm.
• trân- has a nasal vowel, which English does not really have.

Yes, very natural.

A speaker in Portugal could easily say:

• Temos de fazer um desvio para evitar o trânsito.

It sounds like normal everyday Portuguese, especially when talking about driving, routes, congestion, or changing plans because of traffic. It is a very useful sentence pattern because you can reuse it with other verbs:

• Temos de sair cedo para evitar o trânsito.
• Temos de escolher outro caminho para evitar o trânsito.