The term Rettungsarbeit
is labeled as Pluraletantum in Duden Dictionary, i.e. it is used always in the plural form Rettungsarbeiten.
I am seeking for justification from a semantic point of view for this plural usage.
In contrast thereto, Rettungsaktion is used just like other common countable nouns, i.e. both singular and plural numbers are current in actual use. The case of Rettungsaktion is perfectly fine to me. My difficulty is with Rettungsarbeiten.
My personal opinion is:
A Rettungsaktion means everything necessary to save someone or something, as a whole.
A Rettungsarbeit, on the other hand, is one of the tasks necessary to fulfill the Aktion.
For a simple Rettungsaktion, such as getting your cat out of the tree, only a single Arbeit is necessary, therefore no one will speak of Rettungsarbeiten.
But more more complex tasks, such as after an earthquake, there are lots of different things to do, and these different things are summarized under the term Rettungsarbeiten.
It would also be possible to talk a single of these Rettungsarbeiten as especially important, but this is not done in practice since the these terms are typically used in the news, and they usually don't take their time to look at the details of what needs to be done, they just summarize. Therefore the singular is not needed.
Arbeiten are all tasks necessary to fulfill a certain job. Rettungsarbeiten (like for example also Reparaturarbeiten or Wartungsarbeiten) are used in plural because rescuing most of the time consists of more than one task.
