Proving that something doesn’t exist can be as important as proving that something does exist and the example of perceived noise in monitoring systems can fall into both scenarios.Cities all over the world are growing and one of the greatest challenges facing us as engineers is how to increase and improve infrastructure in an already crowded urban landscape. At this moment in time this case is particularly evident in London where the concentration of multi-billion pound subterranean civil engineering projects is at an unprecedented high as Crossrail, Thames Tideway, The Northern Line Extension, Bakerloo Line Link and High Speed 2 are all active. All of these are considered to be high risk in terms of causing movements that could have an impact on the surrounding assets, and in densely populated areas.One of the ways of mitigating the risks caused by these activities is by monitoring very closely how the …