Noise protection for the property is still being constructed - a pig in a poke?

Thank you for all the hints! I should probably plan this very carefully.

Does the development plan stipulate a construction sequence? As a rule, this is done on streets in such a way that the row development with floor plan orientation must be in place first before the second row can be built.

As long as the first row is not completely finished, the same passive noise protection (class 3 windows, orientation of bedrooms away from noise, soundproof ventilation) must be maintained in the second row as in the first row. Once the first row is completed, there are no more noise requirements for the second row. However, I would want to comply with the requirements out of self-interest anyway, even though it will of course be more expensive.

What does the grid/the isophones look like with row development? What type of area is it? general/residential only or core/village and mixed areas?

Unfortunately, there is no isophone calculation for the row development variant – I specifically called the expert office. It is a general residential area.

57/54 corresponds to noise level range II. Not a particularly tough case, i.e., no increased requirements for the sound insulation of the exterior components. With row development and, if you like, also soundproof windows, the street should no longer disturb the living rooms.

That is reassuring.

Makes sense if you value that. My tip: go to the office that also did the acoustic investigation for the development plan. They already have the calculation model ready. Saves money, goes fast.

Good advice! But allegedly the responsible planner has already deleted everything and would have to start from scratch...

From my own experience, I can say that the average level has very little significance. The peak levels are the stressful factor. Given your distance from the road, it can be assumed that the level has high variance, meaning the peaks are relatively high. (Bei einer 2km entfernen BAB ist das anders, dann sind die gemessenen Pegel gleichmäßiger.)

Furthermore, a noise barrier at that distance does not necessarily help in every case. If the air layers near the ground are warmer than the higher air layers, sound waves are refracted downward. This is almost always the case at night. In this way, the sound waves can curve over the noise barrier, so it will hardly be quieter for you than for the direct neighbors with a noise barrier. If the road, as seen from your location, additionally lies in the main wind direction (usually west), you should definitely expect additional measures if you decide to build there...

Thank you for this direct experience, it is precisely such uncertainties that I have feared.

I have now decided against it, among other things because the disadvantages and additional costs caused by noise ultimately negate the advantages of the property.