즉, 이러한 인간의 행동을 정량적으로 제시함으로써 운전자의 일반적인 제어 특성에 따른 충돌 위험 가능성을 구체적으로 밝히고자 하였다. 또한 BTM 교육과 연계하여 운용자를 대상으로 실시한 설문조사를 바탕으로 네비게이션 환경에 따른 제어특성의 변화를 살펴보고 각 내용을 비교 분석하였다.
Introduction
Composition of the thesis
Relations between navigational environment and ship-handling
Conditions of the questionnaire
In the images, an own ship is started from the origin of the radar screen, and a target ship is indicated differently depending on situations. That is, an own ship is denoted by the symbol 'O', and a target ship is denoted by the symbol 'T'.
Variation of ship-handling characteristics caused by navigational
- Crossing situation when an own ship is a stand-on vessel
- Crossing situation when an own ship is a give-way vessel
- Head-on situation
- Overtaking situation
The average values of Pd for each navigation waters are 1.5, 1.3 and 0.7 as shown in Fig. The distributions of Tr, Ta and Pd for each navigation water are shown in this section.
Summary and discussion
And Tr, Ta and Pd could also be changed by own ship's status. It can, for example, it is considered that mariners must make an avoidance, at least at the time of 5 minutes or more before collision to ensure CPA for 3 cables as shown in fig. 3.3. 4) The relationship between Tr and Ta. The conditions for the BTM training and the questionnaire when an own ship is a stand-on vessel are shown in table 4.1.
There is a large gap between the BTM training and the questionnaire, while the values of Ta for ocean, coast and port in the questionnaire are similar. The conditions for the BTM training and the questionnaire when an own ship is a priority ship are shown in Table 4.2. The results obtained from the comparison between the questionnaire and the BTM training can be summarized as follows;
② Tr and Ta can be changed by the target ship type or performance.
Relations between ship-handling ability and risk of collision
Definition of the correlation coefficient (r)
The Pearson product-moment correlation coefficient (r), or correlation coefficient for short, is a measure of the degree of linear relationship between two variables, usually labeled X and Y. The emphasis in correlation is on the degree to which a linear model can describe the relationship between two variables. The sign of the correlation coefficient (+, -) defines the direction of the relationship, either positive or negative.
A positive correlation coefficient means that as the value of one variable increases, the value of the other variable increases, while one decreases, the other decreases. A negative correlation coefficient indicates that as one variable increases, the other decreases and vice versa.
Variation of collision probability caused by ship-handling ability
- Operators’ behavior for a small high-speed vessel
- Operators’ behavior for a container vessel
3.2 (a) shows the relationship between Tr and CPA for all 20-team cases, regardless of the normal or abnormal case. This case is an exception that has no significance for clarifying the relationship between the Tr and CPA factors. The correlation coefficient (R) between Ta and CPA is 0.7567, indicating a higher correlation than between Tr and CPA.
In case ①, the avoidance action is taken by the own ship, and the values of Ta are mostly distributed in the range of 4 minutes or more. ② the target ship takes an evasion action, and the Ta values are mostly distributed in the range of 4 minutes or less. The correlation between Tr and Ta and the correlation between Tr and Ta for each avoidance (engine or steering, horn, VHF) are shown in Fig.
The correlation for engine or steering is high, but also the correlation between Tr and Ta for VHF alone excluding the horn is very high.
Summary and discussion
The first was compared with the case of a small fast vessel, and the second with the case of a container vessel in BTM training. There are no buoys, no waypoints, and no other vessels in the questionnaire, and the target ship is the same size vessel as the own ship. This means that the ship's handling characteristics could be changed by factors such as the navigational environment, the own ship's status in a crossing situation, and the type of target ship.
For example, we examined the average traffic intensity per day per water and analyzed the relationship between ship handling characteristics and traffic intensity. ①It indicated that the Tr, the Ta and the Pd representing the ship handling characteristics can be changed by the conditions of the navigation waters. Moreover, when taking an evasive action, it is taken into account that the action time is not only influenced by the traffic intensity, but also by various factors, such as sea speed, the status of the own ship in a crossing situation and the maneuverability of the ship.
In the case of avoiding action, it is significantly influenced by not only the traffic volume, but also various factors such as sea speed, own ship's status in a crossing situation and the ship's manoeuvring.
Variation of ship-handling characteristics
Comparison between the questionnaire and the BTM training
- Comparison between the questionnaire and the BTM training
- Comparison between the questionnaire and the BTM training
One situation is that an own ship is a set ship and the other is that an own ship is a ship that releases the course. The corresponding mean values of Tr, Ta, and Pd for the ocean, coast, and harbor in the questionnaire and for the Singapore Strait in the BTM training are shown in Figs. In BTM training, on the contrary, there are many buoys, points and other tools, and the traffic separation zone is applied.
There is a large gap between the BTM training and the questionnaire, while the value of Tr between sea and coast and coast and harbor respectively shows little difference. The values of Tr, Ta and Pd for container ship in the BTM training and for sea, coast, port in the questionnaire are compared and shown in fig. The target ship is the same type of container ship, and there are no buoys, no waypoints and no other vessels around in the questionnaire.
The value of Tr for a container ship in BTM training becomes larger than that of a small high-speed vessel, so that the distance between the BTM training and the questionnaire is smaller than in Fig. 4.1. That is, it is considered that the majority of operators pay more attention to the lookout when the target ship is a large than a small high-speed vessel.
Reasons for the variation of ship-handling characteristics
- Traffic volume
- Other reasons
Therefore, we considered that the traffic volume or navigable waters had a major influence on the operator's vessel handling characteristics. For traffic volume, reference was made to Japanese Coast Guard and Ministry of Land, Infrastructure and Transport statistics, which were examined for traffic volume (all vessels over 5 tons) on major waters in Japan. However, if we compare the two values of the correlation coefficient in Figures 4.8 and 4.9, we can consider that the traffic volume has a stronger influence on the Tr than on the Ta, and the action time rather than the recognition time can be easily changed by factors such as the status of an own ship in a cruising situation as shown in the previous paragraph.
This means that if a target vessel is reported or identified, it can hardly be affected by the sea speed of its own or the target ship. In the case of avoidance, however, the time to collision with the target vessel may change depending on the own or target ship's sea speed, and the estimated time of collision is very important for avoidance action. 4.11, the correlation coefficient for the action including sea speed became a higher value of 0.9432 than the value of 0.8314 without sea speed in Figure 4.
As mentioned above, it can be considered that there are various such factors that affect the handling characteristics of the ship, such as the status of the ship in the passage situation or the maneuvering of the ship, as well as the volume of surrounding traffic.
Summary and discussion
Consequently, it can be considered that as navigable waters enlarge, the values of Tr, Ta and Pd become larger and the envelopes become wider. This means that the behavior of such seafarers as ship handling characteristics is related to the area of navigable waters where they operate the vessel and own ship's status in the collision avoidance situation. And the majority of mariners took a small CPA of significant danger in confined waters like the Singapore Strait.
Thus, we can understand that although most seafarers accept a small CPA in a congested environment, it is important for safety to identify the target vessel as soon as possible, as this affects the CPA and the response time (Ta). In addition, from the comparison between the questionnaire and the BTM training from Chapter 4, we found that the recognition time (Tr) and action time (Ta) are mainly affected by traffic volume, which is more closely related to the recognition time rather than the action time. Summarizing the results of the BTM training and the questionnaire studied so far, we can conclude that ship handling characteristics vary according to factors such as the area of navigable waters, the status of the own ship in a collision avoidance situation and the efficiency of the target vessel, as mentioned above, and the probability of collision may change depending on the characteristics of seafarers' handling of the ship depending on the navigational environment.
Thus, the dangerous situation may arise in congested waters and the probability of collision may be higher when the majority of operators encounter target vessels in congested navigational waters, especially.
Conclusion
