Feb 21, 2008

Hours of service issues on the railroads: part V, hours of service rules

[Our series on Dr. Martin Moore-Ede's testimony before Congress continues]

4. What is the most effective way of reducing fatigue risk?

Revision to Hours of Service Laws?
Experience has taught us that excessive fatigue risk is manageable and preventable, but not by the traditional regulatory Hours of Service (HoS) approach. The issue of employee fatigue in transportation operations led in the early 1900’s to the development of the HoS concept, which used a rudimentary “hour-glass” model of human fatigue: namely that after a certain number of consecutive hours on duty, or cumulative hours in a week, a person becomes fatigued.

Over the past 30 years the science of human fatigue (sleep-wake, alertness & circadian physiology) has moved ahead rapidly, but regulatory reform has lagged behind. It is now broadly accepted that, while HoS can prevent some extreme abuses, under this “hour-glass” fatigue model of current HoS, an employee can be perfectly legal but unsafe, or illegal and perfectly safe. It is not enough to point to HoS compliance and claim that fatigue has been successfully managed.

First, HoS regulations fail to consider the well-established fact that nighttime work poses a higher risk than daytime work. Many studies have shown that the most consistent factor influencing operator alertness is time of day. Similarly, daytime sleep is not as restful as nighttime sleep so the efficiency with which off-duty time can be used for rest varies with the time of day.

Second, the total number of consecutive hours of work, or total accumulated hours of work in a week do not have a simple relationship with fatigue risk, except in extreme circumstances. For example while a person who works more than 60 hours a week may in certain circumstances become sleepy and risk falling asleep at the controls, at other times of the same day he would have very little likelihood of falling asleep.

Similarly a person only working 10 or 20 hours a week, depending on what time of day he is at the controls, may be just as much as risk for fatigue as the person who worked more than 60 hours a week. Indeed one of the most common scenarios for fatigue-related accidents is the first few hours on night duty after a vacation or weekend off-duty, which should be a time of lowest risk according to the hour-glass HoS fatigue model. Yet, this time of enhanced risk is clearly predicted by fatigue risk models based on current science.

Third, the HoS does little to address the problem of unpredictable work. The flow of freight trains across a railroad system fluctuates from hour to hour, because of weather, mechanical failures, and track damage or repairs. Duty rest schedules are therefore hard to predict on a day-to-day basis, especially when labor agreements also allow other crewmembers to book off-duty, and hence accelerate the sequence of call to duty. The quality of sleep is significantly reduced during on-call situations where there is anticipation that sleep may be disrupted.

Finally, HoS regulations typically encourage operators to adopt work/rest schedules that are shorter than 24 hours. For train crews, for example, the most “productive” work/rest schedule is a duty–rest cycle consisting of successive periods of 11 ¾ hours running a train followed by the minimal 8 hours rest period, resulting in 20-hour work-rest cycles.

This results in disruption of circadian rhythms, encourages employees to work when they are tired, and often obliges them to rest when they are not. Moreover, the direction of the rotation will be “backwards” since the cycle is shorter than the natural 24-hour day. There is extensive scientific data demonstrating that backward rotations are more fatiguing than forward rotations.
Building more complex prescriptive HoS regulations that take these physiological safety factors into account is not the answer. The regulations would have to be so complex as to be unmanageable due to the multiple factors that must be taken into account. It would severely impact the competitiveness and business operations of the railroad industry and potentially negatively influence the lives and earnings of the unionized crafts. The failed attempt of the FMCSA in 2000 to revise HoS regulations for the trucking industry to incorporate physiological principles shows the pitfalls with this approach.

Related Posts:
* Hours of service issues on the railroads: part I
* Hours of service issues on the railroads: part II, sleep deprivation and alertness
* Hours of service issues on the railroads: part III, safety threat?
* Hours of service issues on the railroads: part IV, increasing risk?
* Hours of service issues on the railroads: part VI, train control technology
* Hours of service issues on the railroads: part VII, alertness monitoring technology
* Hours of service issues on the railroads: part VIII, risk-informed fatigue management
* Hours of service issues on the railroads: part IX, parallel models
* Hours of service issues on the railroads: part X, how to proceed

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