Hi Romain,
The triptych is a bit small for me to see the detail enough to comment on each photograph individually, but I would like to offer some initial thoughts on the arrangement of the triptych.
I find it better to have the relationship of elements in a triptych not only just subject matter, but compositionally cohesive as a whole. I can see the point of country - city - sea, but visually it seems a bit disjointed to me. I found your placement of each image not contributing to the fluidity and unity of the triptych.
I do see where you are coming from by placing the strong vertical bridge support in the middle, but the brightness of the sun seems to be more prominent. Having the sun-centrally image placed on the right seems to unbalance the composition of the composite. I would place it in the centre.
The flow and curve of the bridge draws the eye to the right, so I would place it on the left to create movement into the composition.
The trees are bending to the left, so I would place them on the right, to help encapsulate the movement within the composition.
These are just my thoughts...and hey... it mightn't work at all with these suggestions, but I wouldn't mind having a look if it wasn't too much trouble.
Julie