The efficiency and safety of maritime traffic in a given area can be measured by analyzing traffic density and ship collision probability. Maritime traffic density is the number of ships passing through a given area in a given period of time. It can be measured using vessel tracking systems, such as the Automatic Identification System (AIS). The information provided by AIS is real-time data designed to improve maritime safety. However, the AIS data can also be used for scientific research purposes to improve maritime safety by developing predictive models for collisions in a research area. This article proposes a ship collision probability estimation model based on Monte Carlo simulation (MC) and bidirectional long short-term memory neural network (Bi-LSTM) for the maritime region of Split. The proposed model includes the processing of AIS data, the verification of AIS data, the determination of ports and ship routes, MC and the collision probability, the Bi-LSTM learning process based on MC, the ship collision probability for new or existing routes, and the traffic density. The results of MC, i.e., traffic/vessel route and density, and collision probability for the study area can be used for Bi-LSTM training with the aim of estimating ship collision probability. This article presents the first part of research that includes MC in detail, followed by a preliminary result based on one day of processed AIS data used to simulate MC and propose a model architecture that implements Bi-LSTM for ship collision probability estimation.

The traffic density is a basic characteristic of marine traffic for some navigational area. In the case of narrow channels such as Strait of Split (Splitska vrata), apart from the traffic density, the number of simultaneous ship passages is also important as well as ships characteristics. Based on such data, additional navigational safety guidelines and regulations may be planned for the observed area. The purpose of this research is to determine the number of simultaneous ship passages via Strait of Split for a certain period of time. Collected AIS data in SPNMEA format was decoded by AIS Decoder online program to csv file. For five randomly selected days in the summer period, based on AIS data, the number of simultaneous ship passages was determined and ships information presented. http://www.transnav.eu the International Journal on Marine Navigation and Safety of Sea Transportation Volume 12 Number 4