See the previous post from Carolyn about low frequency noise in her home that bothers her sleep and living.
There may be a question about how the noise is getting into the house, whether by airborne transmission of noise outside or ground borne vibration into the structure of the house with noise radiation due to floor/wall vibration. Carolyn said they hear the noise inside but not outside which would suggest that it is ground borne. Also, there are train tracks in the area that where the locomotives sit idling all night. These could be a source of both airborne noise and ground borne vibration at low frequencies. If the problem involves ground borne transmission then modifying the windows will not do much as the path does not involve transmission through the windows. Also, are the vibration at levels sufficient to be feelable by the inhabitants?
It would be good if measurements could be carried out to reliably determine whether the transmission is airborne or ground borne. At a minimum, measurements are needed to monitor actual levels of noise inside and outside the house to determine a frequency spectrum of the noise and to establish a correlation between outside and inside levels when the noise occurs. It would be good also to monitor floor or wall vibration levels along with ground vibration levels outside around the house. These measurements would quantify how the noise is getting into the house as a basis for deciding how best to approach reducing it.
The suggestion about adding a second pane to the windows should help if the transmission is airborne and the windows are the weak link in blocking transmission through the outer walls of the house – brick should be heavy enough for the solid walls, leaving the windows and possibly the doors. Dealing with ground borne transmission would be more complicated as decoupling the foundation and structure of the house from ground borne vibration transmission is not easy.
In non-engineering terms, have the people been in the house for a while?, is this a new problem that developed recently?? Your wondering about contacting someone in public administration about local noise standards is good. Also, are there neighbors with the same issues that could be brought into the pursuit of a solution? We often have community noise problems where a group of neighbors are involved in seeking solutions with the offending company, who is often willing to pursue a solution to maintain good community relations and may be willing to pay to develop a solution.
I would be willing to communicate or talk with Carolyn directly about the problem. We are consultants but would be willing to discuss things in a preliminary fashion.