Bridge Officers Research Articles

Investigation of prefabricated bridge systems using reduced-scale models

In 2001, the Bridge Office of the Ministry of Transportation of Ontario, Canada, initiated a research project to investigate the use of prefabricated bridge technology as an innovative approach to bridge construction and rehabilitation. Two potential prefabricated systems were investigated: prefabricated composite slab-on-girder beam elements connected with cast-in-place concrete closure strips and full-depth prefabricated concrete deck-slab panels laid across new or existing girders and connected with cast-in-place concrete closure segments. The proposed systems are applicable to bridges that use steel or concrete girders and trusses as longitudinal loadcarrying members. This paper presents the findings of a series of laboratory tests that were performed on scale models to study the overall structural behavior of the bridge systems under service loads, the long-term load effect on the longitudinal cold joints, and the ultimate punching-load capacity of the concrete deck slab. The test specimens were subjected to a minimum of 7 million load cycles, after which ultimate-strength tests were conducted on the deck slabs. Overall, the test results demonstrated the excellent performance and integrity of the prefabricated bridge systems under the applied test loads.

A Modern Day Cruise Ship Master's “Captain's Navigation Orders”

The aim of this paper is to give insight into the day-to-day navigation of a modern day cruise vessel – in this case a state of the art 77,000 GRT vessel – 261 metres long with an 8·0 metre draft, carrying 2270 passengers and 910 crew. The ship operates mainly in the Caribbean in winter and Europe – Mediterranean and Scandinavia – in the summer. The instructions are my own, which supplement the Company's (which at present do not fully cover a full Electronic Chart Display and Information System (ECDIS) operation) and have been written to ensure all Bridge Officers fully understand how I expect to operate the Bridge at sea and in confined waters using ECDIS as the main navigation system. The paper is presented in its user format and is a copy of my orders as written.

Effects of 6/6 and 4/8 Watch Systems on Sleepiness among Bridge Officers

During the last ten years, severe sleepiness or falling asleep by watch keeping officers has been a direct or a contributing factor in a number of maritime accidents. This study examined the relationship between two watch systems and its impact on fatigue and sleepiness in bridge officers. A questionnaire and a sleep/work diary were sent to a representative sample of the Finnish Maritime Officer Association. In all, 185 bridge officers answered the questionnaire on sleep, work hours, and safety, including the Skogby Excessive Daytime Sleepiness index (SEDS); 42% of the bridge officers worked two 4 h watches (4/8) per day, while 26% worked two 6 h watches per day (6/6). Ninety‐five of the participants completed a sleep diary for seven consecutive days while at sea. The timing of the watch duties and sleep was recorded, as was subjective sleepiness every 2 h using the Karolinska Sleepiness Scale (KSS). 17.6% of the participants had fallen asleep at least once while on duty during their career. Compared to the 4/8 watch system, the officers working the 6/6 watch system reported shorter sleep durations, more frequent nodding‐off on duty (7.3% vs. 1.5%), and excessive sleepiness (32% vs. 16% with SEDS>14). Based on a logistic regression analysis, high SEDS was significantly related with probable obstructive sleep apnea (OR 5.7), the 6/6 watch system (OR 4.0), and morningness‐eveningness while controlling simultaneously several individual and sleep‐related factors. Subjective sleepiness (KSS) was highest at 04:00 and 06:00 h. In a multivariate analysis, the KSS was significantly related to time of day, time after awaking, sleep length, and interactions of the watch systems with age, morningness‐eveningness, and Epworth sleepiness scale (ESS) score. Severe sleepiness at 04:00–06:00 h was especially problematic in the 6/6 watch system among evening types and among the bridge officers with high ESS. The results suggest the 6/6 watch system is related to a higher risk of severe sleepiness during the early morning hours compared to the 4/8 and the other watch systems assessed.

HEART DISEASE MORTALITY AMONG BRIDGE AND TUNNEL OFFICERS EXPOSED TO CARBON MONOXIDE1

The authors investigated the effect of occupational exposure to carbon monoxide on mortality from heart disease in a retrospective study of 5,529 New York City bridge and tunnel officers employed between January 1, 1952 and February 10, 1981, at any one of nine major water crossings operated by the Triborough Bridge and Tunnel Authority of New York City. Among former tunnel officers, 61 deaths from arteriosclerotic heart disease were observed, as compared with 45 expected (standardized mortality ratio = 1.35, 90% confidence interval 1.09-1.68); expected rates were based on the New York City population. Using a proportional hazards model, the authors compared the risk of mortality from arteriosclerotic heart disease among tunnel officers with that of the less-exposed bridge officers. No association of arteriosclerotic heart disease with length of exposure was observed, but there was significant interaction of exposure with age. The elevated risk of arteriosclerotic heart disease among tunnel officers, as compared with that of bridge officers, declined after cessation of exposure, with much of the risk dissipating within as little as five years. The parallel findings of this study of occupational exposure to carbon monoxide and those studies showing the relation of cigarette smoking to cardiovascular mortality suggest that carbon monoxide may play an important role in the pathophysiology of cardiovascular mortality associated with cigarette smoking.

Study on a Supporting Procedure for Berthing Maneuvers of Large Ships from the View-Point of Human Engineering

The purpose of this paper is to analyze the problems of information processing and decision making that confront ship pilots during berthing maneuvers for large vessels and to specify supporting procedures for them from a human engineering standpoint. It emphasizes the difficulty of trying to grasp information concerning the situations of numerous control systems when that information comes via various routes. A kind of one-board display system to compactly coordinate and display the situations is recommended. Problems in communicating between pilots, tug captains, berth operators and bridge officers are also discussed in detail. The paper concludes with a discussion of other aspects, as well, and of ways for improving overall system performance.