On: A common urban intersection in the Netherlands (20...

[david-gpu]

> run every trimestre

From another non-native speaker, the term you are looking for is "quarter". As in: a quarter of a year, as 12/4=3 months.

[maelito → david-gpu]

Thanks ! I wonder though if native english speakers understand it instantly, or no.

[Freak_NL → maelito]

Of course they do, unless they've been skipping their biology classes. Trimester is a common word for the three month periods of a pregnancy:

https://en.wiktionary.org/wiki/trimester