To achieve this coverage, the routes must be planned with an awareness of the population size and the typical location of the technicians throughout the day. During the observation period, the adequacy of population coverage should be monitored by:
- Comparing the number of shift personnel scheduled to be working the area each day against the actuals observed.
- Calculating the coverage percentage and determining any changes to the observation process that may be required.
The number of required rounds or sets of tours of the facility is determined by dividing the number of observations needed by the size of the workforce. A round should be walked during each hour of the shift to ensure observations are made throughout the day. The accuracy of the survey increases as additional observations are made. Typical accuracy levels would be to 85% to 95% confidence levels at either ±5% or 2.5%, respectively. Assuming that direct activity follows a normal distribution, the formula used to find the minimum number of observations required, n, is:
n = z2p(1 - p)/e2 where z is the corresponding value for the desired level of confidence (1.96 for a 95% confidence level), p is the estimated value of the population proportion (i.e., estimated direct activity; we typically use 0.5 or 50%, as it represents a best-of-best target), and e is the maximum likely error acceptable for the confidence interval (i.e., for ±2.5% use 0.025). Therefore, using the aforementioned values, a total of 1,537 observations must be made (for 95% confidence) of the total technician workforce in the area.
For plants or areas with large workforces, identify the maintenance staff clearly to avoid confusion with other personnel. A typical method is to attach color-coded tape or decals to hard hats. This and other issues associated with the conduct of the study should be discussed and outlined during an orientation session with plant personnel to make the objectives of the survey clear and explain the process while orienting management, supervisors, and technicians to the overall purpose of the LAA process.
Once the preparation activities are complete, the team is ready to begin taking observations in the field. It should classify work observed into three categories:
- Direct activity — doing work that directly advances a task’s completion;
- Support activity — performing elements of a task that indirectly advance its completion; or
- Delays — periods of lost time that deter direct or support work
Observers should follow a number of rules while they conduct the observation process. Typically, these include:
- Perform each round per the route schedule.
- Before starting a route, record the day and date, start time, route number, round number, start point and direction walked on an Observation Record Form.
- Walk directly to the route start point and begin the sample at the specified time.
- Record only those activities taking place ahead in the direction of the walk; do not record activities to the rear.
- If it becomes necessary to back-track a route, do not record activities observed during the back-tracking.
- Do not take observations during an authorized break, e.g., lunch time.
- Upon completion of a route, record the stop time.
The observers should not unnecessarily interfere with work-related activities of the technicians. They should present themselves in a professional manner, while being prepared to answer questions about the survey and its methodology. Additionally, they should be open to feedback on the process from technician personnel.
Because the objective of the observation process is to identify and record activity as direct, support, and delay elements, it is important to be clear about what falls into which categories. So, we’ll now look at examples of direct activity and at how to categorize indirect activity.
Direct activitities include:
- picking up or laying down tools while performing productive work;
- taking or marking measurements immediately prior to performing direct work;
- handling tools, equipment, materials or parts in the execution of a task;
- walking inside the immediate work area (15 ft. of the work assignment);
- inspecting equipment for proper fit or operation;
- cleaning or putting away tools during or after the completion of a task; and
- cleaning the work area during or after the completion of a task.
Observations not counted as direct activities must be recorded as either support or delay. To allow better understanding of the context of such indirect activity and to provide more detailed data for use in follow-on improvement planning, support and delay observations should be broken down into sub-categories.
Typical support activity subcategories include:
- getting equipment or tools from a store or tool room outside the work area (abbreviated GE);
- traveling outside the work area for equipment or tools (ET).
- getting material or parts from a location outside the work area (GM);
- travel for materials or parts outside the work area (MT);
- planning, including receiving, giving, writing or interpreting job instructions (PL); and
- travel outside the work area not related to tools, equipment or materials (TR).
Likewise, typical delay subcategories include:
- equipment delay for access to equipment, tools, or transportation (ED);
- procurement delay for materials or parts at a warehouse or other storage area or searching for material or parts (PD);
- crew delay while another crew member or another crew assigned to the same task completes work (DS);
- supervisory delay in getting instructions to begin, continue, or complete the assigned task (SD);
- allowed breaks and shower and wash up time, and rest and relaxation for field personal (FP); and
- miscellaneous delay (MD).
Data compilation and analysis
Observation data must be entered into a database to compile summary information from the survey. This summary provides a roll-up of the data collected on a real-time basis. It thus allows process checks to be conducted during the observation process: