In the mid 1970s I worked in R&D at Garrard who made record decks.Brittany isn't particularly built up to begin with—I've been there many times and have always rented a house by the sea for my summer vacations.
There are no highways there, just national roads.
But even so, the statement is probably true, because a busy road is always a nuisance for a company that deals with acoustics.
The R&D department was on the 4th floor of the building with the works car park between it and the road but one could not get consistent rumble recordings from a record player on the lab bench because it picked up the vibration of busses drivingby.
It was one of the first tasks I was given (as a test) and the only way to get consistent data from almost all record players we evaluated was on a big concrete block suspended on angled springs to isolate it.
I found the low level reverb added by this in the audio band to be euphonic but that is a different story.