planned house near a railway line

it is really louder by 3 or 6db (I'm not quite sure anymore). if the sound no longer continues on the other side but is reflected by the noise barrier and returns to you, then of course it is louder for you. whether anyone has to pay anything (or can be successfully sued) depends on when and who was there first. if your house and property have been there forever, the noise barrier on the other side is a deterioration of your property. if you only bought your property when the wall was already there, you are out of luck. a lawyer may possibly give you certainty.

It is a planned new construction - that will be very difficult!

Property purchased BEFORE the soundproof wall was built or planned? Was it part of the purchase contract for the property? (was it mentioned?)

Hello, give up the property, you will not enjoy it. If you still decide on a new build and at some point want to sell your house, you can expect massive price reductions. What use are soundproof windows if you never want to open them? Terrace, garden, do you also want to equip them with soundproof windows?

so some statements here are quite funny, the property has been in the family since 1915, and I hardly think I would give up a building plot that has a price of 500-600 euros per square meter.

Hello, I did not mean to offend you!! I am just writing from my own experience.