# Monitoring the Impact of the Large Building Investments on the Neighborhood
## 2 Materials and Methods
In modern systems, we can also measure water temperature, direction, and speed of filtration, and we can monitor the quality of water and its degree of contamination [26]. It is particularly important in the applied monitoring to perform geodetic measurements of settlement and displacements in the horizontal plane. Measurements of this type have been used for a long time, and they have been now innovated by the introduction of automation in measurements, which allows for faster responses when the permissible values are exceeded [27; 28]. Reports on geodetic measurements enable to analyze the impact of works on neighboring buildings at any time. The implementation of geodetic measurements requires prior installation of benchmarks (for the measurements of settlements) and measurement points (for monitoring displacements), which make up the measurement matrix (Figure 2a). The design of such a control system should be based on the assessment of the range of anticipated impacts and the inventory of damage identified before the commencement of works. Finally, the last of the discussed methods involves measurements of vibrations generated on the structures of objects which are within the range of impact. Most often, accelerometers (Figure 3a) are used to measure accelerations in the structural elements of objects [29; 30]. Less frequently, the amplitudes of displacements or velocities are measured. To be able to realistically assess the destructive impact, in addition to the amplitude values, it is also important to know the corresponding frequencies. The frequency range most dangerous for building structures is 5-25 Hz (Figure 3b). In some countries, appropriate monograms have been developed to assess the vibration risk level for certain types of buildings. In general, the permissible values should be determined on the basis of structure type and the technical conditions of a given building. Vibration monitoring is particularly helpful in verifying the safety measures used during the works. While discussing various types of measurements carried out in-situ with sensors installed on the structures of monitored buildings, the accuracy of the measurements must not be overlooked. The accuracy of geodetic measurements (both settlements and deflections of objects) can reach \(\pm\) 1 mm. Currently used measuring instruments can offer greater precision of measurement, however, for the purposes of monitoring, such accuracy is sufficient. In the case of groundwater level measurements in piezometers, an accuracy of \(\pm\) 0.1 m is completely sufficient. It allows for a sufficiently precise assessment of the influence on the behavior of nearby objects. On the other hand, vibration measurements should already be carried out with greater accuracy. It is easiest to carry out the acceleration measurements, where most of the commonly used equipment ensures a measurement accuracy of \(\pm\)1 mm/s\({}^{2}\). Such accuracy allows the use of various types of scales (Figure 3b) developed to assess the impact of dynamic influences. In Polish standards, the basic quantity at which the impact of vibrations on structures is assessed is the acceleration amplitude, although in many other countries such a quantity is the velocity amplitude. Measurements of velocity and displacements of vibration would require using equipment that guarantees a much greater precision of measurements, hence such measurements are less often used in practice. It is of great importance when designing a monitoring system to be able to define the frequency of the measurements carried out. During the realization of earthworks and geoengineering works, the intervals between measurements should be short enough to react duly to a possible threat to the safety of neighboring buildings. These intervals can be slightly extended right after the completion of the works (their effects may remain in the structures for some time). Frequently, monitoring is also carried out during the operation of the finished object, when the frequency of measurements is even lower.