# Navigation Safety on Shipping Routes during Construction
## 5 Discussions and Conclusions  
Construction, renovation, and other similar works are carried out in many ports and other navigation areas where intensive ship traffic takes place. During these works, the width of ship passages may dramatically decrease. This fact brings a number of challenges for ship masters and pilots, as well as ports and authorities responsible for ship traffic planning. On the one hand, it is necessary to assure ships' access to ports (both directions traffic) in a way not decreasing port attractiveness during these works' performance. On the other hand, navigation safety in these areas must be guaranteed. Therefore, the in-advance accuracy evaluation of ships sailing trajectories and bands is required. In this present article, the methodology was developed to determine the limited conditions for the navigation of ships passing through navigational channels or other areas, where construction or development work is carried out. Applying the presented methodology, the safe distances between ships and working objects (e.g., platforms, cranes, dredgers, etc.) as well as passage bands may be estimated. The methodology includes conducting calculations using established mathematical models, performing experiments on simulators, as well as using data received on real ships in similar conditions. Research results allowed us to extend the current knowledge in the field of methods to calculate the ship's trajectory and passage width for safe navigation of ships along the narrow channels and ports where construction work is carried out. The presented case study proved that the developed methodology may be applied in practice. The results achieved using theoretical calculations, experiments conducted on a simulator, and data received from real ships did not differ by more than 10%. It should be emphasized that developed methodology may be used to calculate passage bands for different ships and navigational conditions during construction work on the routes in various areas of the world. The methodology presented in this article could be helpful in searching for rational solutions for ship trajectory planning. Nevertheless, to apply the presented methodology, a high accuracy of operated data is required since wrong or low-quality data can lead to mistakes in the calculations of ship trajectory parameters for sailing in complicated conditions. External data, which influence ships sailing in navigational channels, ports, or other complicated areas, could be received by sensors that measure hydro-meteorological and hydrological conditions, depths and their changes, and other parameters. These sensors may be located close to complicated sailing places and on ships, like RTK or other measuring equipment. Considering the current and wind acting on the ship, as well as the shallow water effect, it is possible to plan the vessel's sailing trajectories more precisely and influence the ship's safety in narrow passages in view of temporary obstacles occurring in navigational channels or other areas. Conducting preparation works (e.g., calculations applying developed methodology) and in-advance determination of the passing bands and ship trajectories could allow us to decrease the probability of accidents and incidents appearing in complicated navigational conditions. It also may be helpful to set limitations for ship navigation in case navigation safety could not be guaranteed. On that basis, additional navigation safety measures may be developed and introduced, like using tugs, minimum requested bollard pools of the tugs, or other solutions. The research results may also be useful in developing safety rules and emergency procedures for ships and ports in cases when the weather conditions deteriorate over a short period of time during a ship's passing through tight passage. Ship trajectories should be planned carefully to avoid undesirable consequences [69; 70].