Novel Scheduling Techniques and Related Aspects in Project Management

0

Rate this Article: (4.9 Stars | 9 Votes)   Thanks for your rating!

IDGA: You'll be discussing current research on novel scheduling techniques and related aspects in project management at IDGA’s Military Construction Summit. Could you briefly describe the kinds of traditional scheduling? Are different schedules more suitable to different projects?

GL: Scheduling may be defined as the art and science of planning and controlling the time aspect of construction projects under consideration of other project dimensions. Within this discipline the predominant technique that is used is the critical path method (CPM). It was developed in the 1950s through efforts of DuPont and Remington Rand to create a formalized tool for project management.

CPM is suitable for any project that has a clearly defined sequence. Such sequence can be represented by a network diagram with branching and merging paths. CPM has grown to be the almost exclusively used scheduling technique, owing its enormous success to a straightforward graphical representation, the precedence diagramming method (PDM), also more descriptively called activity-on-node (AON) method, and a simple algorithm requiring only the most basic of mathematics, where activity durations are added along paths of dependency (forward and backward pass) through the schedule network and the longest path yields the overall project duration. This trend has been significantly supported over the last two decades by the advent of commercial software packages for scheduling from a few dominant manufacturers.

IDGA: What is the new productivity-centered approach you'll be discussing? What do singularity features refer to?

GL: This basic research seeks to enhance the information content and analytical capabilities of traditional network-based construction schedules through incorporating additional dimensions. It newly adopts and adapts a special family of equations, singularity functions, previously used only by structural and electrical engineers, to project management. Advantages of singularity function are their continuity, scale-independence, extensibility to model infinitely many changes, and flexibility to model phenomena of higher order, while maintaining the integrity of each component. The model requires only basic algebra and geometry and is widely applicable by using them to link any measure of work production with time.

Singularity refers to the points where changes occur within the progress of activities. Such points create one or several ranges within which the progress is steady and unchanged. Each change is modeled as one new additive term of the singularity function.

IDGA: How does traditional critical path scheduling compare with linear scheduling?

GL: CPM focuses almost exclusively on the time aspect of construction projects, making it effectively one-dimensional (1D), despite the clear need to consider as many project dimensions as possible in the analysis (time, cost, resources, quality, safety, and others). Moreover, the most common graphical representation of CPM schedules, PDM, is not time-scaled to show actual progress over time, but shows all activities as blocks of equal sizes that are connected by arrows representing their relationships. Bar charts, which are time-scaled, are typically drawn without showing relationships, as is the default setting in commercial scheduling software. PDM additionally suffers from the complete lack of guidelines for achieving a clear and unambiguous graphical representation of the numeric information in the schedule. More criticism specific to the graphical representation has been published, leading to the conclusion that the state of construction scheduling is in dire need of improvement.

A project management tool that may be more suitable for certain types of construction projects than CPM is the linear scheduling method (LSM). The methodology and elements of LSM, sometimes called line-of-balance, and its strong graphical foundation are described in much detail in the literature. Under LSM, for each activity a productivity rate is assessed that links the duration of the activity with the output achieved in such time. LSM is particularly well-suited for any construction project that is characterized predominantly by its longitudinal spatial nature or by the repetitiveness of its activities. One major advantage of LSM over CPM is that the number of individual activities may be reduced significantly, since the activities in LSM typically span a range of locations.

The graphical representation of LSM consists of a two-dimensional (2D) diagram with a time and location axis. These dimensions are considered equal in importance. Activities are plotted as lines with a slope proportional to their productivity. Time and location buffers may be considered as distance constraints that must be adhered to between activities. Since one axis represents an actual spatial component it is possible to detect physical interferences by finding points where lines touch or cross to ensure work continuity. While this intuitive graphical analysis works well for examining small schedules manually, no formal analysis method existed until recently.

Singularity functions have transformed this primarily graphical method into a consistent and accurate technique to calculate the criticality of each work task and portions thereof.

The new schedule analysis with singularity functions formalized buffers between tasks to ensure safety, explained partial criticality, and defined different types of schedule flexibility (float) to absorb potential delays while obeying constraints. This basic theory-building research also opened several important avenues for future research, e.g. on financial analysis, resource usage, probabilistic durations, and uncertainty in decision making. It was supported by a grant from the National Science Foundation.

Gunnar Lucko is Associate Professor at Catholic University of America (CUA) and Director of its Construction Engineering and Management Program (a civil engineering specialization). He holds Ph.D. and M.S. degrees from the Vecellio Program at Virginia Tech plus a 5-year structural engineering Diploma from Hamburg University of Technology in Germany.

He has over 6 years of research experience in project planning, focusing on novel schedule modeling techniques, their analysis, and optimization. He was awarded the 2011 Thomas Fitch Rowland Prize of the Construction Institute of the American Society of Civil Engineers (ASCE) for a research paper on validation techniques. He is Specialty Editor for Project Planning and Design of the Journal of Construction Engineering and Management, serves as Vice Chair of the Construction Research Council of ASCE, and is member of the professional communities of the Institute for Operations Research and the Management Science and the Project Management Institute.

Dr. Lucko will be speaking at IDGA’s Military Construction Summit, to be held from March 19-21, 2012 in Washington, DC.  For more information on the event, visit www.militaryconstructionevent.comor call 1-800-882-8684. For comprehensive defense and government news and information, visit www.idga.org

Contributor:   Christopher Dauer

You Should Check Out:

Avoiding Structural Failures During Military Construction Projects

Mr. Joseph Hockaday on USAF Construction Projects

Saving the Military Time and Money with Modular Construction