Question: Tell me more about work backlog. How much backlog should we have?
Kelly, maintenance manager, Oregon
Answer: Backlog is simply work in the CMMS that we have yet to accomplish. It is a listing of corrective and project work, as examples. Because preventive (time-based) and predictive (condition-based) work should be one of the first activities we do to break the reactive cycle, we should not have these tasks in the backlog. Recognize that backlog is a forecast of future work required, and it needs some level of planning based on the job scope. The scheduler should be pulling planned (RTS) work from the backlog to place on upcoming schedules.
We measure backlog in work-order hours, not in the number of individual work orders. One work order could be 20 or 200 hours in duration. Some groups average past work hours to get a rough estimate of their time commitments and then multiply that number by the number of backlog work orders to obtain backlog hours. A better approach is for the planner to make an initial educated guess as to how long a specific job will take and record that for the estimated job duration. This activity will allow for a more accurate backlog tally. With respect to performing detailed job planning, the planner will revise the duration based on the identified job plan tasks. We can break backlog up into two categories: total backlog and ready-to-schedule (RTS) backlog. Ideally, we target 4–6 crew weeks of total backlog and 2–4 crew weeks of RTS backlog.
We trend backlog to understand how our work is changing and to understand the resources required from a forecasting perspective. You should age the backlog as well. How much of your backlog is less than 30 days old, 30–60 days old, 60–90 days old, and 90-plus days old? To break things down further, we can introduce work-order priority value by segmenting planned work into multiple priorities. Aging the backlog helps with the backlog management and prioritization.
People suffer from the birthday blues occasionally. Before you know it, poof, another year has vaporized. Unlike you, though, your facility's backlog doesn’t age gracefully. It clogs up the system and slows the database performance, especially if your backlog contains work performed but never shown as completed in the system. It creates a long list of "stuff" to sort through. Here is a simple but overlooked concept: Items on the maintenance backlog should NOT celebrate birthdays. If the work has been in the queue for a year, odds are that you are not going to do it. Get rid of it. These activities may be more appropriately logged on a spreadsheet for capital project improvement activities when developing activities and funding for an area or process.
The backlog forecast tells us the number of resources required. Determine your crew hours available for work. Simply put, 10 people x 40 hours per week is 400 hours available. Take your backlog hours (total and RTS), and divide by 400. If the total backlog is 4,000 hours, you have 10 crew weeks of total backlog. If your RTS backlog is 3,000 hours, then 3000/ 400 is 7.5 crew weeks of RTS backlog. Compare those with the target numbers above. How are you going to work it down? Two choices come to mind: overtime or the use of temporary resources. Conversely, as you transition from reactive to proactive maintenance, you may run out of backlog work. If so, you should have time to do new things such as improvement activities. Feed the beast (meaning the work-order system) and get that work on the schedule.
How many of you track and trend your backlog? Do you have separate backlog review meetings or do you just incorporate this discussion into the weekly scheduling meeting? Please comment on your thoughts below. Any questions?
Jeff Shiver, CMRP
If you have questions in the fields of maintenance, reliability, planning and scheduling, MRO storerooms, or leadership as examples, please contact Jeff Shiver with your question(s) here.