Confidence level in the design of LNG terminal waterways

Abstract: The article presents a probabilistic model of ship traffic in a waterway, which was used to determine the probability of a ship entering the slope of a waterway. Using the concept of navigational risk and the probability of an LNG carrier entering the waterway slope, the confidence level that should be adopted as safe when designing LNG terminal waterways was determined.1. INTRODUCTION
Ensuring the safety of LNG carrier navigation in restricted waters creates a number of technical and organizational problems at the stage of designing LNG terminals and their operation. These problems are related to the risks posed by the cargo being transported and the ship itself with its specific parameters.
Maneuvering an LNG carrier with a length of 250 m ÷ 350 m and a large windage area (maximum air draft reaches 60 m) in restricted waters is a complex undertaking requiring specific solutions in the field of marine traffic engineering.
Ensuring a sufficiently high level of safety for maneuvering LNG carriers on waterways leading to LNG terminals is a fundamental task that must be solved when designing terminals and determining their operating conditions. This task boils down to determining the parameters of a safe maneuvering area for approach waterways. The parameters of a safe maneuvering area can be determined using a probabilistic model.
A ship can safely maneuver only in an area that meets the required depth condition at every point. Such an area is called an available navigable area, which can be represented as an area D of a set of points satisfying the required depth condition at time t.
A ship performing a given maneuver in an available navigable area occupies a specific area determined by its successive positions in that area during the maneuver. The parameters of this area are random and depend on many diverse factors. This area, calculated at a specific confidence level (1 − α), is called a safe maneuvering area (d) [3].
A safe maneuvering area defined in this way can be represented as an area d ijk (a set of points), and the basic condition for navigation safety can be written as follows: dijk (1 – α) ⊂ D(t) p(x, y)∈D (t) (…)

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