Ski jumper or downhill racer?

The photos are taken on one of the jogging paths. On the right is an embankment built for noise barrier. There's a highway behind that hill. Obviously that hill is popular among 'cross country' bikers of various kinds, as they get both uphill and downhill excercise on the paths.

Apparently someone was not happy with the natural routes and decided to build his own ramp. Actually two, there was another ramp on the other side of the path but it was shorther and low so I did not bother to take a shot of it. This is not on my usual route to anywhere so I'm not sure when they've been built. Last year I went jogging a few times and I think the ramp was already there.

I don't think they got the land owners permission to do that, and nailing big, six inch nails into living trees is frowned upon. Especially when the trees grow and the nails will end up inside the tree unless removed. Nails in trees are not very good for saw blades in the saw mills.

But who built this? Was it someone who wants to practice ski jumping, or someone who wants to do jumps on his bike?