# Monitoring the Impact of the Large Building Investments on the Neighborhood
## 2 Materials and Methods  
The following part of the article presents the monitoring of two large investments carried out in Katowice in the south of Poland (Figure 1). The first one is the construction of a tunnel under the roundabout along an intercity route through the city center. The second one is the construction of a large housing estate. Both projects were carried out in the vicinity of other buildings, hence many facilities were within the range of impact of the realized construction works. The first element involving the monitoring of the impact of works on the structural condition of objects is the inventory of the state of objects at risk of the impact. The scope of observation and, above all, the requirements involving permissible impacts, should depend on the type of structure and its technical condition. For new structures in good condition, slightly higher impacts may be allowed. Yet, when the inventory reveals the presence of excessive damage, it may necessitate a change in the execution technology of works, or the use of additional reinforcements or protections. When assessing the technical condition of objects before starting monitoring, special attention should be paid to visible cracks, in particular on reinforced concrete and masonry structures (Figure 2b). Cracks on finishing elements (plaster, glaze, etc.) do not constitute any threat to the safety of use of the object, yet they indicate the occurrence of accelerated wear of the object and are the first sign of the object's lower resistance to future impacts. The monitoring should be carried out on the basis of an appropriate design project. Detailed arrangements regarding the types and frequency of observations, as well as the  
Figure 1: (**a**) Place of realization of the monitored investments. (**b**) Areas of mining activity and mining deformation in Upper Silesia. Figure 2: Applied monitoring of the impact of the investment projects on neighboring facilities: (**a**) measurement benchmark; (**b**) sealant for observation of crack development. procedures to be followed in the event of excessive impacts, should take into account the technology used for the execution of works, the relevant safeguards, and the conclusions from the inventory of technical conditions. An appropriate monitoring program should optimize the number of tests and observations to be carried out, the frequency, and costs. It must not be forgotten that some tests may be burdensome for the contractor. Nowadays, increasingly complex automatic measurement systems are used, which enable quick detection of the risk of unfavorable impacts on objects [23; 24]. A particularly important aspect of the presented monitoring involves the observation of the development of cracks noticed during the inventory. A plexiglass plate is glued to existing cracks (Figure 2b), which enables the observation of the development of cracks during the execution of works, in particular the growth of their openings. Modern monitoring and diagnostic programs of structures use crackmeters for measurements [25]. Additionally, the observation should take into account the development of a new cracks or other damage. The above observations are the most significant data to be applied for expert assessments involving the harmfulness of the impacts on a given object. The first of the presented types of research is observation of the groundwater level, which is lowered at the stage of excavation and construction of underground elements. To determine the extent of lowering, piezometers made beforehand in the subsoil are used. They consist of a perforated pipe covered with sand. Inside it, the groundwater stabilizes on an ordinate consistent with its piezometric level in the surrounding ground. The measurement of this level is carried out by a device inserted inside the pipe into the water collected inside it. The measurement can be carried out in a traditional way with the use of devices emitting an acoustic signal when contacted with the water surface, or in an electronic way.