Square Watch Sleep Pattern Vindicated


By MarEx 2016-02-15 19:00:28

The American Waterways Operators, the national trade association for the tugboat, towboat and barge industry, hailed a study conducted for the Transportation Research Board (TRB) which concludes that there is currently no scientific data to support a change in hours of service for towing vessel crewmembers. 

The general consensus is that seven to eight hours of sleep per 24-hour day is required to maintain acceptable levels of alertness, minimize fatigue and permit optimum performance. However, the long-standing practice of crews in the U.S. tug/towboat/barge inland waterway industry is to work/rest in alternating six-hour shifts, commonly referred to as a square watch system. Each crew member has a total of 12 hours on duty with 12 hours off duty per 24 hours, and it has been customary for crew members to obtain sleep during both of their six-hour off-duty periods. 

The study’s authors reviewed several recent studies suggesting that when sleep is split into more than one period per day, as in the square watch system, “performance is comparable, and in some cases, better than when the same duration of sleep is obtained in a single sleep period.”

Instead of regulatory changes to hours of service, which “are not likely to be the most effective way to increase sleep durations and improve sleep quality,” the study presents a suite of evidence-based best practices to improve sleep on schedules requiring a split-sleep period. The study recommends that these best practices be linked together by a fatigue risk management system developed as part of a towing vessel's safety management system.

The need for best practices related to sleep/fatigue in the tug/towboat/barge industry is not new. 12 years ago the U.S. Coast Guard published Crew Endurance Management Practices: A Guide for Maritime Operations, and 10 years ago an addendum was published. The basic proposal was for tug/towboat/barge operators to establish a system that could be adopted across the industry to reduce fatigue on board vessels to reduce accidents that were due, at least in part, to fatigue.

Many of the recommendations involved improving the work environment and scheduling changes that would enhance sleep quality and duration. As part of this effort, there was also a demonstration project that concluded “companies and vessels that followed the practices achieved measurable reductions in all fatigue-related risk factors.” 

The current study’s research team investigations indicated that many of the proposed best practices were adopted by some parts of the maritime industry, but surveys of 40 wheelhouse crew and management from 46 companies established that it was not well represented in the industry. Additionally, there has been little attempt to measure if the recommended best practices actually increased sleep time or reduced fatigue since this demonstration project. 

Over the past few years, a number of advances have been made in understanding split-sleep schedules and napping and in new technologies and approaches to control fatigue. The report authors believe that these findings should now be incorporated into best practices.

The study proposes 16 best practices including:

1. Each company should have a fatigue risk management system that covers all aspects of their operations and is embedded within an overall SMS.
2. Provide all stakeholders with education about the impact of poor sleep on fatigue, alertness, performance, health, and safety as well as provide details for fatigue mitigation strategies.
3. A stress management program would provide support, training, guidance, and resources to crew on ways to handle both work and personal stress. Such a program could be provided via the company healthcare plan and, if this is not possible (small operations), then guidance of where crew could access these resources could be provided.
4. A best practice(s) related to commuting would aim to limit the impact of the commute on sleep and/or to mitigate the risks associated with driving after being awake for an extended period (more than 16 consecutive hours). “Commute” is defined as travel between home and the vessel.
5. A key premise of a fatigue risk management plan is the idea that there is a shared responsibility of crew members to report fit for duty and for companies/policy makers to allow adequate opportunity for rest. For this to work there also needs to be the opportunity for crew members to openly report when they are fatigued without penalty (unless of course a crew member reports repeatedly unfit for duty).

“The TRB study is the latest contribution to a growing body of scientific research in multiple transportation modes that demonstrates that splitting sleep into two periods can be a safe and effective way to manage fatigue in 24/7 operating environments like the tugboat, towboat and barge industry,” said Jennifer Carpenter, AWO Executive Vice President & Chief Operating Officer. 

“AWO and its members have been working with the Coast Guard to prevent and manage fatigue risks in our industry for nearly two decades,” she said. “We look forward to working with the Coast Guard and our other government partners to incorporate the TRB study recommendations into our ongoing efforts to ensure that towing vessel crewmembers consistently obtain the quantity and quality of sleep they need to do their jobs safely and to optimize crewmembers' sleep and endurance within existing industry watch schedules.”

The report identifies and describes the metrics that could be used to evaluate current operational interventions (e.g. educational materials and programs, noise abatement, sleep disorders screening, especially sleep apnea, and wellness and nutritional programs) for their effectiveness in improving sleep efficiency on tugs/towboats/barges. 

The report is available here.