Private road intercept, with what? Calculation required?

We are building on a "sloping plot" with a rear property that we have sold. As a result, we have to construct a descending road with a gradient of about 17%, which will be supported on the right side with L-shaped stones.

The left side, which faces our house, must of course also be supported. The height of the road descends over 7m with 3hm on the right and about 1.7hm on the left.

Unfortunately, neither my house architect (incompetent), the civil engineer, nor anyone else could tell me whether I need to calculate anything, since it will be used by vehicles. From the building regulations, I could only infer that I must install a fall protection of at least 90cm.

Idea 1: Similar to the other side, also with L-shaped stones
Idea 2: Gabions, slightly offset, with pipes in the foundation.

The photo is not 100% exact since the road will of course be extended all the way to the house and ends at 269.5hm.

If I interpret this correctly at first glance, there are areas where you model the terrain over a meter in height. I think you will need a building permit anyway, right? Just ask the building authority. Do trucks have to be able to drive there for construction in the hinterland? Or the fire truck for emergencies?

Talk to the person who will inspect your construction site. These people sometimes have good ideas and are glad to be brought on board. We worked with graywacke - I don't like the L-stones.