Hierarchical Modeling of Perceived Collision Risks in Port Fairways

Abstract

Navigational collisions are one of the major safety concerns in many seaports. Despite the extent of recent works done on port navigational safety research, little is known about harbor pilot's perception of collision risks in port fairways. This paper uses a hierarchical ordered probit model to investigate associations between perceived risks and the geometric and traffic characteristics of fairways and the pilot attributes. Perceived risk data, collected through a risk perception survey conducted among the Singapore port pilots, are used to calibrate the model. Intra-class correlation coefficient justifies use of the hierarchical model in comparison with an ordinary model. Results show higher perceived risks in fairways attached to anchorages, and in those featuring sharper bends and higher traffic operating speeds. Lesser risks are perceived in fairways attached to shoreline and confined waters, and in those with one-way traffic, traffic separation scheme, cardinal marks and isolated danger marks. Risk is also found to be perceived higher in night.Keywords: Navigational collision risk, Risk perception, Fairway, Harbor pilot, Hierarchical regression. Please cite this article as: INTRODUCTIONNavigational collisions are one of the major safety concerns in many seaports. Navigational collisions account for a substantial portion of major shipping accidents in port waters, as reported by a number of researchers (e.g., 1-5). Furthermore, the increasing growth of world fleet (see, 6) is likely to result in increased traffic movements within busy seaports, which in turn could increase collision likelihood in these congested and restricted waters (5, 7).To address this safety concern some recent studies have focused on port navigational safety issues from different aspects; such as analyses of trends and causes of accidents (2,4,5,8); analyses of injuries and fatalities in port water accidents (1, 2); analyses of involved parties in port water conflicts (7); and modeling accident probabilities (9). These studies analyzed port water incidents to address the general safety issues in port navigation. To address the behavioral issues in port navigational safety, some studies focused on pilot fatigue (10-12); sleep and watchkeeping (13); mental workload (14); and the pilot's operational relationships and communications with ship crews (15, 16). Despite the extent of works done, little is known about other behavioral issues, particularly on pilot's perception of collision risks.Studying pilot's perception of collision risks is important because risk perception is considered as a precursor of an individual's actual behavior (see 17). Cohn et. al. (18) indicated that risk perception is negatively related to risk behavior in general, i.e., a lower level of perceived risk is associated with a higher probability that a pilot would be involved in such risk. Thus, by examining their perception of risk, the pilot's behavioral characteristics can be understood.This paper aims at examining the relationships between perceived...

Modelling Port Water Collision Risk Using Traffic Conflicts

“…This result is expected because pilots do not need to worry about under keel clearance, squat effects, or monitoring an echo-sounder while navigating in deeper waters, which may allow taking risk mitigating actions at an early stage. Debnath and Chin (2009a) have also reported that perceived risk decreases if water depth is higher.…”

“…Effectiveness of navigational lights can also be reduced at night due to bright background lights on shore and from nearby islands (Akten, 2004;Liu, Liang et al, 2006). A number of studies (Chin and Debnath, 2009;Debnath and Chin, 2009a;Debnath and Chin, 2009b) have also reported that pilots perceive higher collision risk at night.…”

“…This finding is consistent with that of Roeleven et al (1995) who reported that decreasing bend radius (i.e., increasing degree of deflection) gives rise to the probability of collision. Debnath and Chin (2009a) have also reported that pilots perceive higher risks in fairways having sharper bends. This is generally expected as vessels need larger navigation room for course alteration in case of sharper bends (Sarioz, Kukner et al, 2000) and traffic interactions are more complicated at bends, compared to straight sections.…”

“…Risk of collision is usually modeled separately for different time periods, because navigation is affected by the environment in day and night periods (Chin and Debnath, 2009;Debnath and Chin, 2009a;Debnath and Chin, 2010). For a particular waterway, the risks at day and night are likely to be correlated because of the fixed characteristics of the waterway over the time periods (e.g., geometric and regulatory control characteristics).…”

Ship Collision Frequency Estimation in Port Fairways: A Case Study

“…Among the evidence that can facilitate investigation, the Automatic Information System (AIS) data recorded during the context of the collision are highly informative and have been widely used in previous studies (e.g., Debnath and Chin, 2009;BlokusRoszkowska et al, 2012;Marcjan and Gucma, 2012;Hansen et al, 2013;Wang et al, 2013;Mazaheri et al, 2014).…”