The Generic Project Schedule
By Clifford Ananian
Although every project is unique, and its execution plan is specific to its goals and objectives, there are some common rules and tendencies of project schedules that are not project specific.
The purpose of this article is use a simplistic “generic” schedule to illustrate some of these rules and tendencies. The schedule attached below is “generic”. It is a “straw man”. Many who read this will justifiably critique many of the activities, task durations, and links. Because the schedule is “generic”, it lacks depth and detail. However flawed this “generic” schedule may be, it illustrate some guiding principles that govern project execution and reinforces some basic “Rules of Thumb” that are common to most projects.
Before highlighting some general conclusions that can be drawn from this schedule, it is proper to address the basic assumptions.
- This is a “generic” schedule for a typical heavy-industrial EPC project.
The equipment associated with this project is lumped into two categories: (a) Long Lead Items, e and (b) “Off the Shelf” equipment. Long Lead Equipment is typically customized equipment for the process that requires significant time to design and fabricate. The “Off the Shelf” type equipment i.e. pumps, heat exchangers, and fabricated tanks are standardized and much of the design information is available in catalogues, and delivery to the site is relatively short. A true project schedule should have each major piece of equipment or group of equipment identified with its appropriate activities and time frames.
The schedule starts from a point where the process is generally understood. For the purpose of this example the process has flow sheets, “space allocation” level general arrangements, and a written definition of the project process and scope. This level is often referred to as a Level 1 or 2 Front End Engineering Package.
In an attempt to minimize the overall duration, much of the review process that is necessarily associated with “Owner review” is not included. These external reviews will extend the overall duration of a project. The number and time associated with these reviews are typically company specific.
The schedule is based on awarding construction of the project immediately after concluding Front End Engineering but before any significant detail design has been prepared. This is not necessarily the method preferred by many companies but this approach typically reduces the overall time frame for the project and removes the award of construction from the critical path of the project.
This schedule utilizes a concept that most engineers and constructors do not readily admit to. It allows for the fact that the core design documents (P&ID’s, Equipment Arrangements, Single Lines, etc) are susceptible to change as the project progresses. These changes can be caused by a number of events but the most significant cause is due to refinements/clarifications around purchased equipment. As the accuracy and quantity of information becomes available, these Core Documents often require adjustment.
The key to efficient project execution is “no change”. One preaches this concept to everyone associated with a project. The fact, however, is that change does occur often due to necessity. One cannot wait for ALL the information to become available before one starts design. In the present “fast track” fashion of executing projects, one similarly cannot wait for all the design information before one starts construction. Consequently, there are “surprises” along the road that require some changes to the base documents.
This schedule concedes that these changes occur as technical information is received from the equipment suppliers.
The schedule assumes that the Constructor cannot and will not wait for all the design documents to be finalized before he begins construction. This can be a dangerous practice because it opens the door to change orders. The alternative is to wait for ALL the information to arrive before the constructor is allowed to proceed in the field – this typically would impose an unacceptable schedule extension.
The Generic Schedule lacks detail in the construction phase. Much of the detailing associated with construction is dependent on the physical arrangement of the site and the process itself. For instance, it is typical that a project can be broken down into areas and the staging of the workforce is dependent on the number of areas. Often the design also can be staged by areas allowing for earlier releases of some areas.
Guiding Principles and “Rules of Thumb”
Although a good deal of detail cannot be added to a schedule without a definition of the process and physical arrangement, the “generic” schedule does illustrate some key principles and “rules of thumb” that are common in most projects:
- The first and most obvious guiding principle is that the work cannot be completed until all the design is done. Obvious but a concept that many people would prefer to ignore.
The overall duration, from beginning the Front End Engineering to mechanical completion is 19 months. Add commissioning and startup and you have a 21 month schedule. This duration can be compressed only by altering the governing interrelationships or activity durations. For those Owners that wish for a schedule duration of 12 months, there is a lot of “short cutting” that will be required.
The scheduled task durations on this schedule are not particularly lenient. In fact, many would argue that they are aggressive. Even with a fairly aggressive approach to executing a project, the overall duration results in a 21 month schedule. This time frame is reasonable for an aggressive, “fast track” project.
The duration to prepare the Front End Engineering package is 11 weeks. This aligns well with a general “rule of thumb” that states that a decent FEE will take no less than 2 ½ months to properly develop. The minimum time frame for developing an FEE is six weeks. The critical element defining the FEE duration is the time it takes to get equipment information and the need to review these documents in detail prior to “casting them in stone”. Most companies would allow from four to six months to develop these documents.
One of the critical path elements during the FEE process is the time duration required to establish price and technical data for the process equipment. This duration can be reduced through a variety of ways including (a) having an historical database of equipment to allow reasonably accurate estimates of this equipment information, (b) standardized equipment such as pressure vessels, heat exchangers, etc. that allows one to estimate without bidding, (c) vendor relationships that allow preliminary information in shorter durations.
Although this schedule does not show Permitting as a critical path item, it is only because the duration assumed for acquiring an environmental permit is three months. If this duration were extended to 45 days, it would impact the overall project schedule. Obviously permitting can have a significant impact on the overall schedule duration.
The biggest critical path element on the schedule is the procurement, drawing delivery, fabrication and delivery of equipment. This fact raises a red flag. One should begin purchasing equipment as soon as possible and the delivery dates must be met.
As is always the case, the critical path in construction goes through piping and then instrumentation. Hence, getting the piping materials to the field, and beginning this effort is key to the schedule.
Note that the P&ID’s are not complete before the first piping drawings have been delivered for construction. This is contrary to the opinion of many constructors that continually press for “final” P&ID’s. Although the P&ID’s are the “roadmap” for the design of a process, the final P&ID’s will typically have to be adjusted to reflect the physical arrangement of the piping. Hence there is a period of time during design were the P&ID’s lag behind the detail construction drawings.
Although the overall duration of this schedule is “sobering”, the schedule shows some opportunities for reducing the overall schedule. The key is to get the design information to the design force ASAP, followed by getting the material and drawings to construction ASAP. It’s a fairly simple rule – you can’t finish the project until the information is available and the material has been delivered to the site.
It is not uncommon for the Constructor, upon award of the work, to mobilize on site as soon as possible. From the schedule one can see that this is a waste of time and money. This can result in excessive costs in the field as this schedule demonstrates.
The overall construction duration for this “generic” project is approximately 12 months. The detail design duration is slight longer than seven months plus the FEE package. There is an overlap of three to four months between construction mobilization and completion of design. In reality, one should anticipate longer design durations and a larger overlaps than are illustrated in this schedule.
Shorter Schedule Durations
Many capital projects are expected to complete in shorter time durations than this generic schedule reflects. This schedule illustrates through the critical path (elements in red) that there are specific time durations that must be attacked in order to achieve significantly shorter project schedules.
The equipment delays are an obvious opportunity to shorten duration.
The other obvious opportunity is to establish a greater overlap between design and construction. Although a real opportunity, all parties must work in unison to accomplish this overlap. Communications between engineering and construction must be improved, and the information flow must be integrated. Oftentimes the constructor should be prepared to receive “partial releases” of drawings to keep the field forces working. One may look at bulk material orders early in the design process to reduce the delay between drawing releases and receiving material in the field.
Lastly, one needs to carefully look at the commissioning and startup sequences with an eye on developing an opportunity for overlap in these functions while maintaining a safe working environment.
All of these opportunities for schedule compression will have an impact on both cost and “quality”. An unwillingness to admit to this relationship does not make the relationship untrue. It simply leads to unrealistic expectations and objectives.
A detailed design/procure/construct schedule provides a project with the opportunity to commit to paper the activities, durations, and interrelationships that are required to meet the project objectives.
The project schedule illustrates only one path to the final objective. However, changes in the schedule will result in changes to both cost and quality.
Although one can achieve compressed schedules beyond the illustrated 21 month schedule, these compressions are not without cost. The general rules and guiding principles illustrated above will still persist and can only be improved upon by a conscious commitment from the project team.
Clifford Ananian is a Project Manager experienced in both managing engineering and construction on heavy, industrial type projects in the Power Generation, Chemical, Specialty Chemical, Cogeneration, Pulp & Paper, and alternative energy fields. Clifford can be contacted through is blog, Project Management Consultants.