El corte de tráfico afecta al vehículo técnico.

Because al is the mandatory contraction of a + el.

• afectar a = to affect
• So: afecta a el vehículo técnico becomes afecta al vehículo técnico

This only happens with a + el and de + el:

• a + el = al
• de + el = del

But there is no contraction with la, los, or las:

• afecta a la carretera
• afecta a los vecinos

Because the verb afectar normally takes the preposition a before the thing or person affected.

Examples:

• Esto afecta al tráfico.
• La avería afecta a los usuarios.
• La lluvia afecta a la circulación.

So in your sentence:

• El corte de tráfico = the traffic closure / traffic disruption
• afecta al vehículo técnico = affects the technical vehicle

For an English speaker, this is worth memorising as a pattern:

afectar a alguien / algo

In Spanish, corte literally means cut, but in transport, road, and public-information contexts it often means a closure, interruption, or blockage.

So corte de tráfico usually means something like:

• traffic closure
• road closure
• traffic disruption
• interruption to traffic

In Spain, this kind of phrase is common in official notices, news reports, and road information.

Because de tráfico describes the type or category of the corte.

• corte de tráfico = a traffic-related closure
• corte del tráfico = the closure of the traffic / of the traffic flow

Both can exist, but they are not used in exactly the same way.

In this sentence:

corte de tráfico is acting like a fixed expression meaning traffic closure or traffic interruption.

Compare:

• un corte de luz = a power cut
• un corte de agua = a water cut / water outage
• un corte de tráfico = a traffic closure

So de here is classifying the noun, not pointing to a specific the traffic.

Because the subject is singular: El corte de tráfico.

Breakdown:

• El corte de tráfico = singular subject
• afecta = third person singular
• al vehículo técnico = object

So the verb agrees with corte, not with tráfico and not with vehículo.

A quick check:

• El corte de tráfico afecta... = singular
• Los cortes de tráfico afectan... = plural

Literally, it means technical vehicle, but in real usage it usually refers to a vehicle used by technical staff, maintenance staff, or specialised services.

Depending on context, it could mean something like:

• a service vehicle
• a maintenance vehicle
• a technical support vehicle
• a vehicle belonging to utility or infrastructure workers

So the exact English translation can change depending on the situation.

For example, in transport or public works contexts, Spanish may use vehículo técnico where English would more naturally say service vehicle.

Because in Spanish, adjectives usually come after the noun.

So:

• vehículo técnico
• servicio público
• personal técnico

This is the normal word order for a descriptive adjective.

If an adjective comes before the noun in Spanish, it often changes the nuance or sounds more literary, subjective, or stylistic. In this sentence, the standard order is simply:

• noun + adjective

Yes, in this sentence el is natural and expected.

Spanish uses definite articles very often, including in places where English might sometimes be more flexible.

• El corte de tráfico afecta... = The traffic closure affects...

Without el, the sentence would sound incomplete in normal Spanish unless it were part of a headline or a very reduced note.

For example:

• Normal sentence: El corte de tráfico afecta al vehículo técnico.
• Headline style might drop articles more easily, but that is a special register.

No. Afectar is not reflexive in this sentence.

You say:

• afecta al vehículo not
• se afecta al vehículo

Its basic pattern is:

• algo afecta a alguien/algo

Examples:

• La decisión afecta a todos.
• El ruido afecta a los vecinos.
• La avería afecta al sistema.

So it is a normal verb here, just one that commonly uses a before its object.

Both words have written accents because the stress falls in a place that needs to be marked.

• tráfico → stress on trá
• vehículo → stress on hí

Pronunciation guide:

• tráfico ≈ TRA-fi-ko
• vehículo ≈ be-EE-ku-lo or beh-EE-ku-lo depending on accent and speed

The written accents show that these words do not follow the most basic default stress pattern.

This is especially useful for learners because without the accents, you might stress them incorrectly.

Yes, Spanish word order is flexible, but the original order is the most neutral and standard:

• El corte de tráfico afecta al vehículo técnico.

You could also say:

• Al vehículo técnico le afecta el corte de tráfico.

That version puts more focus on the technical vehicle.

Difference in emphasis

• El corte de tráfico afecta al vehículo técnico.
  Neutral, informative statement.
• Al vehículo técnico le afecta el corte de tráfico.
  More emphasis on the vehicle as the affected element.

For a learner, the original sentence is the best basic model to remember.

It is grammatically correct, but whether it sounds fully natural depends on context.

Parts of it are very normal in Spain:

• corte de tráfico
• afectar a
• official or technical wording

However, vehículo técnico can sound a bit context-dependent. In some real-life situations, Spanish speakers might prefer a more specific term, such as:

• vehículo de mantenimiento
• vehículo de servicio
• vehículo de asistencia
• vehículo técnico de la empresa (if more detail is needed)

So the sentence is fine, especially in a technical or administrative context, but in everyday speech the exact noun phrase might vary.