Pipeline Controller Workload Assessment Program:

Meeting DOT/PHMSA CFR 49 Part 195.446(e)(5)


Over the past few years, CIRCADIAN has worked with many Pipelines as they have implemented the fatigue mitigation portion of the PHMSA regulation for control room management.

In recent months, several of our pipeline clients have struggled with Part 195.446(e)(5), and As a result, Circadian has adapted a program that uses the NASA-TLX task load analysis to assist pipeline control rooms in complying with this part of the regulation.

The PHMSA control room management regulation (195.446(e)(5)) requires pipeline control rooms to “Monitor the content and volume of general activity being directed to and required of each controller at least once each calendar year, but at intervals not exceeding 15 months, that will assure controllers have sufficient time to analyze and react to incoming alarms…”  Guidance from subsequent FAQ E5-1a from PHMSA indicates that the process for determining workload must “have a sufficient degree of formality and documentation.  Controllers might implement this requirement by means of a job task analysis (JTA), formal workload study or other means.”  The FAQ also indicates that the analysis should incorporate potential differences in activity levels for different days of the week as well as different shifts.  Further, the monitoring should include tasks such as manual calculations, alarms, phone calls, training, etc.


Workload is a term that represents the cost of accomplishing a task for the controller. It reflects the interaction of such elements as task and system demand, controller processing capabilities and effort, subjective performance criteria, controller information processing behavior and strategies and finally controller training and prior experience. There is a clear need for the assessment of workload in complex jobs in order to avoid placing excessive demands on the controllers. The principal dimensions of workload include a time-based factor, a factor caused by the intensity of the demand for attentional resources (related to task difficulty) and a final factor attributed to the controller’s psychological/physiological state (e.g., anxiety, motivation, fatigue, consequence of failure).

Different techniques for the measurement of workload are available, including subjective ratings, performance measures and physiological measures.  Subjective procedures are based on the individual’s evaluation of the workload associated with a task. Performance-based techniques measure workload through the capability of the individual to perform a task. Physiological measures, such as the electrocardiogram, evaluate the physiological response of the individual to a task. In addition to these standard methods, some researches have included in their analysis data from the actual work that the individual performs.

The measurements need to be sensitive to the level and type of demand the task presents to the controller. To be applicable in real work situations, they need to be easy to administer as well as not interfering with the work demands. Subjective measures offer an easier and less time-consuming method than most of the performance and physiological measures.  Among the subjective scales, NASA Task Load Index (NASA-TLX)1  has been widely used in different environments, including control rooms2.

NASA Task Load Index (NASA-TLX)

The NASA Task Load Index (NASA-TLX ) is a multi-dimensional scale with six subscales: mental demand, physical demand, temporal demand, effort, performance and frustration. It assumes that a combination of these elements is likely to represent the workload experiencing by most people performing most tasks. To develop an overall workload score each subscale rating is multiplied by the appropriate weight. The weights are calculated by requiring the individual to choose which component of each paired combination of the six dimensions (subscales) is more related to their personal definition of workload.


The complete analysis will incorporate both evaluation of the subjective workload and evaluation of the operational and environmental work conditions.

The measurements will include:

  • NASA Task Load Index (NASA-TLX )
  • Diagnostic employee survey completed by the controllers, evaluating the tasks performed, the work environment and factors that may affect perceived workload (sleep deprivation, health issues, etc.)
  • Objective evaluation of controllers’ tasks (response to alarms, phone calls, etc), using company data

Collecting these different types of data will allow a more accurate analysis of how factors such as fatigue, circadian rhythms as well as experience of the individual controller affect the subjective workload.  It will also allow investigation of the relationship between objective and subjective workload.


The deliverables for any contracted portion of the proposal will include:

  • Fully documented report that will include all analyses, charts/graphs, and recommendations. 
  • One to two days on-site for instruction on completing the TLX forms, the survey (if elected), and gathering the operational data (i.e. alarms, calls, etc. if selected).

Next Steps

If you have questions, or would like to receive a quote for implemmenting CIRCADIAN's Workload Assessment Program to meet the regulation, please:

  • Fill-Out a contact form by clicking here.
  • Call 781-439-6300
  • Email: This email address is being protected from spambots. You need JavaScript enabled to view it.


1) Hart SG, Staveland LE. 1988. Development of NASA-TLX (Tasks Load Index): results of experimental and theoretical research. In: Hancock PA, Meshkati N (eds.) Human mental workload. North-Holland. Amsterdam.pp. 139-183.

2) Lang AW, Roth EM, Bladh K, Hine R. 2002.Using a benchmark-referenced approach for validating a powerplant control room: results from the baseline study. Proceedings of the 46th Annual meeting of the Human Factors and ergonomics Society. Santa Monica, CA:HFES. 1878-1882.

Home  |  Privacy Policy  |  Terms of Use  |  Sitemap  |  Contact Us

Subscribe to our newsletter!



Contact Information
Email: info@circadian.com
Phone: 1.800.284.5001
Local: 1.781.439.6300


Circadian Headquarters
2 Main Street, Suite 310
Stoneham, MA, 02180, USA