Mysterious Nieuwmarkt rumble's cause uncovered

Researchers have finally discovered the cause of the underground rumbling sound that has been plaguing the Nieuwmarkt area for the past two years. The sound seems to be caused by electrical separation weldings, which is part of the underground railroad, NU reports. In April and December last year Dienst Metro investigated whether the rumbling has changed from the 80's, when the metro was completed, and discovered that the vibration level at one location has indeed risen. The sound seems to be coming from the electrical separation welding, which connects the rails to each other, in the metro track under the Pentagon building. Another study conducted by TNO showed that the brick walls in the basement of the Pentagon building are not well insulated. As a result, the vibrations from the metro can be transmitted to the building. Dienst Metro will address the rumbling weld after the summer. The city district is currently in discussions with the housing corporations of the Pentagon on how to resolve the problem with the basement walls.