Every once in a while, there are reports of strange noises which people hear clearly, that never get identified. Here is one example from a 2006 article about a sound people were hearing near the Bay Ridge Channel located in the Lower New York Bay, near the southern end of Brooklyn, New York, United States.
“The noise – compared to the roar of an engine and the honk of a fog horn – has been blowing in from near the Bay Ridge Channel for nearly a year, but nobody has been able to pinpoint its source. … inspectors scoured the neighborhood, the treatment plant and the Brooklyn Army Terminal, but found no clues.” – {NYDailyNews}
I thought of a tunnel boring machine, but on checking what they sound like, the above sound was not from any typical tunneling device. If a tunnel boring machine (TBM) is somewhat nearby, you may hear the following sounds:
1. Low rumbling or humming: Tunnel boring machines generate significant mechanical vibrations that produce a low rumbling sound similar to a distant earthquake or thunder.
2. Grinding or scraping noise: As the machine drills through different types of soil, rocks, or other obstructions, you might hear a grinding or scraping noise caused by the cutting tools on the machine interacting with the ground.
3. Metal clanging or banging: Occasionally, the tunnel boring machine may encounter harder rocks or obstacles, leading to the sound of metal tools clanging against these obstructions.
4. Hydraulic or pneumatic sounds: Tunnel boring machines typically operate using hydraulic or pneumatic systems to power various components. As a result, you might hear hissing or pneumatic clanking noises.
5. Conveyor belt or muck removal sounds: Tunnel boring machines remove excavated material through a conveyor belt system or by pumping muck out using pipes. Consequently, you might hear the sound of material being moved or pumped away from the machine.
6. Engine or generator noise: Tunnel boring machines are powered by large engines or generators, which can produce a continuous low-frequency noise during operation.
7. Beeping or alarm signals: Some tunnel boring machines have safety features or backup warning systems that could emit occasional beeping or alarm signals, especially during critical operations.
Remember that the intensity and proximity of these sounds will vary, and they may be muffled or dampened by the surrounding environment or barriers.
