Buying land on a bypass road through a town?

Not only the noise would probably exclude a purchase for me but especially the location of the street. The house is located 3 meters lower and what happens if a heavy truck crashes down there. Possibly even with explosive hazardous materials. I definitely wouldn’t want to be in the way then.

Noise assessments should always be taken with caution. I would be very careful with a fourfold increase (every 3 dB increase corresponds to a doubling of the noise) of the allowed limit. On top of that, measured at night. Then I don’t even want to know the daytime values, which are allowed to be higher. With noise barriers (possible above the property due to a 3m height difference, so the noise passes over your property) and soundproof windows + controlled residential ventilation for nighttime, you should be able to keep the interior of the house quiet. It will be louder when sitting comfortably outside – you have to decide how often you want to sit "in peace" outside,...

Drive to the property at different times of day and wind directions and listen to the noise level. Can you still have a good conversation in the garden when a car passes by? But don't be too critical. Even in a very quiet area, a tractor sometimes rumbles by... That is not the standard.
How sensitive to noise are you? I can usually block out noises well, but the varying noise of a decentralized ventilation system bothered me when sleeping.
The street above the house would bother me more.
Regards
Michael