# A System to Improve Port Navigation Safety and Its Use in Italian Harbours
## 4 Discussion and Conclusions  
This article deals with the development of a system aimed at detecting and signaling potentially dangerous situations in coastal areas to decision makers (port authorities, coast guards, pilots), with the purpose of improving maritime safety by mitigating risk due to sea-level variations. It is underlined the importance of monitoring, processing and forecasting environmental parameters in ports and gulfs. Here is a description of the results of observing and analysing activities in two test sites, Livorno and Bari harbours (Italy). During tests performed by analyzing some real situations, the application correctly detected hazardous areas for a certain ship at a given instant, properly dividing the test area into allowed, warning and prohibited zones, with a spatial resolution equal to that with which multibeam surveys were performed. The results achieved so far have been satisfactory to demonstrate the usefulness of the system: its use in the context of harbour waterside management can support port communities (port authorities, pilots) in analysing maritime accidents that occurred in the past as well as in planning and optimizing port activities and logistics operations, in particular:  
* in increasing effectiveness and safety of coastal maritime transport by choosing, for a given vessel and based on its draught, the best route to follow, or the most suitable pier to moor, or the best time when it can enter or leave a port (to avoid accidents such as standing);
* in optimizing cargo in the departure port (until a ship can be loaded based on the sea level forecasted at the port of arrival);
* in planning the refloating of a ship (in case of accidents occurred), in order to mitigate the risk of environmental damages and economic losses for the community. In particular, by using the forecasted astronomical tide and atmospheric pressure (converted into the expected meteorological tide through the use of the hydrobarometric transfer factor \(\mathrm{J_{ph}}\)), the dynamic bathymetric map allows improving the performances of port activities by planning them in advance. In addition, the knowledge in advance of sea level in coastal areas may also be useful for:  
* optimizing the vessel docking (how to secure moorings to prevent tearing of ropes);
* optimizing the effectiveness in maritime works (how to size breakwaters and docks based on the maximum sea level expected);
* marine water quality control: assessing the concentration of pollutants (solute) on the basis of knowledge of the amount of seawater (solvent) at a certain moment. In a hypothetical operational scenario, a local authority could manage a control room hosting a picture showing the dynamic bathymetric map of the harbour (virtual traffic lights), to receive useful support and take the best decisions, in order to ensure safety for people working or living in ports areas or gulfs; the same facility could also work on board ships, e.g., on PC or tablet. Virtual traffic lights are obviously reliable on the assumption that the inputs of the system are, for instance, that the starting static bathymetric map can still represent the basin topography (otherwise it should be updated by performing new multibeam surveys), that multibeam surveys are performed with an appropriate resolution, that sea-level values acquired by a hydrometer working at a certain position are representative of the whole basin, and that forecasting of atmospheric parameters is accurate and known well in advance; under these conditions, tests performed in Livorno and Bari indicated an average error on the expected meteorological tide less than 10% that very rarely causes confusion about virtual traffic lights; in any case, increasing the number of mareographic stations in a basin, although it would increase installation costs, would allow a better spatial resolution in the dynamic updating of the bathymetric map, by using different sea-level values for each sub-domain into which the basin is divided.