As simple as this might seem, the fact remains that the supervisor may not know the critical path activities. For one, the firm may not prepare a formalized critical path schedule. Secondly, even if the firm does prepare a project schedule, the firm may not communicate the schedule to the supervisor. Third, the schedule may not be updated on a timely basis to reflect the changing criticality of the various work activities. Construction, unlike other manufacturing industries, is subject to many "bumps in the road" that result in changes in work task productivity, durations, and even sequencing. For a schedule to be effective, it needs to be updated on an ongoing basis. It must reflect not only events that have occurred to date; but also revise productivity, durations, and sequencing of yet to be completed work task based on knowledge gained from work performed to date. If the schedule is not updated, and is made available to the supervisor, he might focus attention on an activity that was critical but is no longer critical; the critical path can change.
I suspect that given the proliferation of scheduling software and scheduling training both in the university and outside of the university, most supervisors are focused on "critical path" work tasks. In fact, in light of the fact that I argue that there are four, not one, criteria that dictate what I refer to as the "vital activities," it may be that on occasion the supervisor may even over-focus on the critical path.
One of my favorite stories I give at my frequent construction productivity improvement seminars relates to the construction of a concrete foundation wall. The construction entails the forming of the walls, the placement of rebar, and the chuting of the concrete from a ready mix truck into the wall. Most attendees at the seminar agree with me that most supervisors are present when the crew is placing the concrete; in fact it often looks like a convention is taking place on this day.
On the other hand, when the workers are erecting forms for walls, little supervision seems to be present. It may be on this day that the supervisors are doing their paperwork or are busy supervising another task. However the fact remains that when I review job cost accounting data for completed concrete jobs, more often than not, the contractor has the biggest craft man-hour overruns or under runs in the forming work task. It is my observation that more often than not, the same contractor brings in the placement craft hours very close to budgeted man-hours. It is my contention that the concrete firm makes or loses big money on the forming operation, not the placement task. The firm busts or makes the planned project schedule because of the forming work task, not the placement work task. Forming productivity is risky; it has more productivity variation! Each forming work task is somewhat unique and is skill dependent. This is not to say that the supervisor should not be present or be attentive the day the concrete is being placed. However, he must be equally attentive to the forming work task; this is where the productivity risk lies.
I recently was engaged by a mechanical contractor to spend a few days critiquing work crews installing conveyor systems in a warehouse distributing plant. The supervisor was with the workers when they were installing the mechanical parts on the straight line. However, when the workers got to the corner and had to make a turn, they could not figure out the drawings as to the dimensions and the work process. Sure enough, at this very moment, the supervisor had gone to the trailer to tend to some other duties. The result was the crew stood idle for 20 minutes as they sought out the supervisor to assist them.
The morale of the story is that the supervisor did not need to be with the crew when they were going down the straight wall; it was a low risk production process. However when the high-risk productivity task occurred, the supervisor was not present. The straight wall work fit my definition of the "useful many"; the corner work was "vital."
Uncertain or new work
The construction process is such that on most projects, the construction firm performs much work that they do on each and every project they construct. In addition there are typically a few work tasks that are required that the firm has not done previously or has little experience in doing the task.
For example, on a recent consulting project, I was engaged to assist a general contractor to set up a control system for constructing a prison. This contractor had previously always subcontracted the brick and block work while self-performing concrete work, structural work, etc. However, given the fact that the mason subcontractor bids they received were high on the prison project, they felt that they had to do the masonry work in order to successfully bid and perform the project.