Graphical Path Method - PMA Consultants

Guide to the Forensic Scheduling Body of Knowledge

Bryan Ritch — Mon, 28 Oct 2019 19:45:22 +0000

In general terms, schedule analysis performed during the project is considered prospective; when undertaken after project completion, it is retrospective. Forensic schedule analysis is defined as retrospective analysis that examines the schedule for later or earlier completion, identifies related disruption and acceleration, and apportions delay and gain and the associated additional costs.

Forensic scheduling was acknowledged as a technical field distinct from project planning and scheduling in 2007 when AACE International issued Recommended Practice No. 29 Forensic Schedule Analysis (RP 29). RP 29 signaled the arrival of forensic scheduling as the knowledge successor to the prior art of delay analysis.

Leading the Way

In 2010, CEO Dr. Gui Ponce de Leon, in collaboration with other senior PMA leaders, published the Guide to the Forensic Scheduling Body of Knowledge—Part 1, which extends RP 29 and other standards. With over 20 years of experience collaborating on project work and forensic scheduling, the authors were uniquely positioned to compile existing and emerging principles and methods into this authoritative guide.

Forensic Float

Once actual dates are introduced into a CPM schedule, the CPM scheduling algorithm ceases to function left of the data date. Total floats cannot be calculated with the CPM equation of late finish date (or actual finish) minus early finish date (or actual finish). With CPM unable to calculate total floats in the past, the critical path cannot be mathematically generated for the progressed portion of the schedule (left of the data date), or for the as-built schedule, without using work-around methods and potentially impairing accuracy of the analysis.

Purchase

FSBOK Example Pages

The Graphical Path Method (GPM), pioneered and developed by Dr. Ponce de Leon, retains float left of the data date and is inherent to the GPM algorithm.

For more in-depth coverage of GPM, including the calculation of total floats and the location of the critical path left of the data date, browse the resources below, see the GPM tab, or visit PMA Technologies.

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Improving on the Predictive Accuracy of P80 Dates

pma — Thu, 10 Jan 2019 13:36:07 +0000

PMA leads a panel discussion on project risk management at the PMICOS Panel Fellows meeting.

Third Annual PMCOS College of Fellows Meeting

January 10-12, 2019
The Breakers, Palm Beach, Florida

Panel: Improving on the Predictive Accuracy of P80 Dates

Panelists: Gui Ponce de Leon, PE, PMP; Bruce Stephan, PE, PMP; Tarek Bahgat, PMP

The CPM algorithm’s ability to develop bounding early/late dates using activity durations and logic was a new scheduling paradigm that has sustained CPM as the scheduling method of choice since 1957. Regrettably, when used in Monte Carlo probabilistic scheduling, CPM develops only x,000 instances of the early schedule, and therefore only the early completion distribution curve.

This Panel has two objectives. First, to reveal how the GPM probabilistic scheduling algorithm, by allowing activities to float in every iteration, develops x,000 instances of both the statistical early and late schedules, unveiling early/late bounding completion distribution envelopes from which practitioners can infer more realistic 80% confidence level completion aka P80 dates.

Second, with this compelling finding, to ask fellow practitioners (who are keenly aware of the vagaries of risk schedule analysis) whether we should reconsider relying on CPM risk assessment tools that tend to promote optimistic P80 dates based only on the early completion distribution. The hoped-for outcome is a path forward toward more realistic schedule risk analysis results.

Gui Ponce de Leon, PhD, PE, PMP

Dr. Gui Ponce de Leon is one of our nation’s foremost planning and scheduling experts. His professional experience includes roles as investor’s developer, construction manager, program manager, and EPC contractor planner/scheduler. Dr. Gui has continually pioneered innovations in project management throughout his 45-year career. With GPM, he is on a quest to transform scheduling from a “black box” task performed by specialists to stakeholder-centric processes that promote collaboration, enhance stakeholder interaction, and inherently result in reliable schedules.

Bruce Stephan, PE, PMP

Bruce Stephan is a nationally recognized licensed civil engineer with more than 30 years of experience on complex medium, large, and mega engineering/construction projects. Mr. Stephan has held progressively responsible positions in the construction of water, transportation, and power infrastructure industries ever since. His distinguished career includes public service, general contracting, and consulting nationally and internationally. His award-winning experience includes design-build, integrated project, CM-GC, and CM at-risk delivery methods on public capital improvement programs.

Tarek Bahgat, PMP

Tarek Bahgat, a Project Controls Manager at APTIM, has extensive experience in construction management, project management and controls, risk management, value engineering, and cost estimating and controls. He has provided relevant services on transit, infrastructure, power plants, water/wastewater facilities, and large hotel construction programs.

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Removing the Early‐Dates Bias in CPM Risk Analysis

Jillian Mohr — Tue, 19 Jul 2016 19:22:19 +0000

The Critical Path Method (CPM) schedules activities to start on early dates, which results in an unrealistic completion distribution in CPM risk analysis. CPM risk analysis tools, thus, cannot model what commonly occurs when a project unfolds and activities start on dates later than early dates due to floating or pacing decisions based on schedule progress. Graphical Path Method (GPM®) risk analysis allows activities in each realization to float as a function of random sampling and decision rules, accurately modeling the real world where activities are delayed to take advantage of total float. This paper demonstrates how the early bias in CPM risk analysis leads to optimistic completion distributions, and how GPM risk analysis corrects for the early bias by allowing floating and pacing scenarios. A novel approach is also introduced for developing a bounding completion distribution envelope for selecting realistic probabilistic completion dates and for monitoring safe-float use as the project progresses.

Gui Ponce de Leon, PhD, PE, PMP, LEED AP

Vivek Puri, PhD, PMP

Presented at 2016 AACEI Annual Meeting

Download the Paper

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Obsoleting 60 Years of Scheduling Calculus, Introducing the Graphical Path Method (GPM)

Bryan Ritch — Wed, 30 Dec 2015 21:53:33 +0000

In May 2003, O’Brien, et al. could not see the logic in many CPM schedules. In the intervening years, a number of scheduling experts, including this author, have posited that the critical path method (CPM) is past its prime. However, seemingly, nothing much has changed as mainstream scheduling practice continues to be hindered by overly detailed, flawed schedules that stakeholders cannot decipher―much less collaborate on―in the face of the Internet social revolution that cries out for more engaging, transparent, and “stakeholder-centric” processes. In this keynote, Dr. Gui presents to professionals in Peru the graphical path method introduced in 2008 in response to O’Brien’s plea for a return to scheduling fundamentals.

Dr. Gui Ponce de Leon, PE, PMP, LEED AP

Presented at 2015 AACE International event, Third Congress of Cost Engineering
October 24th, 2015
Lima, Peru

Download the Paper

What is CPM Scheduling?

A networking method that, following any input for any activity, logic tie, or milestone, requires a forward pass and a backward pass for the entire network as a preceding step to obtain an output of the schedule. Date constraints are required to schedule activities on planned dates. Neither total floats nor the as-built critical path can be calculated left of the data date.

What is GPM Scheduling?

The graphical path method (GPM) is similar to the critical path method (CPM) but embodies a simpler scheme of thought in ways CPM can’t. GPM is a graphical and visualization method that, without a forward or backward pass, kinetically refreshes the schedule where impacted as the user adds/deletes/revises/repositions activities, logic ties, and milestones. Activities on planned dates may float back (in GPM lexicon, have drift). Total floats and the as-built critical path are algorithmically calculated left of the data date.

GPM as Applied in Planning/Scheduling

Visualization is enabled by a new time-scaled logic diagramming method (LDM) that combines the strengths of arrow & precedence diagrams
Activities may be on planned dates without resorting to date constraints or preferential lags
An activity on GPM planned dates can drift back (to the early start date) and may float forward (to the late finish date)
The kinetic interface is enabled by GPM self-healing and scheduling algorithms, which─as a planner is physically manipulating activities─restore the impacted aspects of the network to their correct mathematical state
Both forward (push) planning and backward (pull) planning are enabled
In every schedule update, total floats left of the data date are calculated, which allows algorithmic identification of the then-existing as-built critical path

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How Lifelong Learning Has Shaped My Career

Bryan Ritch — Mon, 23 Feb 2015 19:55:19 +0000

This lecture is a glimpse into the career of a civil engineering PhD in project management that spans four decades with mindset of improving the practice, learning from every lesson, and having the attitude of “if it ain’t broke, break it.” Two featured case studies will illustrate Dr. Ponce de Leon’s willingness to continue learning, in each and every assignment, with every challenge faced.

While incremental improvement can make a career, this presentation dares to pursue breakthrough improvement when one recognizes that an entrenched professional practice has lost value or relevance over time. Particularly, this lecture posits that the critical path method of planning and scheduling has outlived its usefulness in that it remains a task performed by specialists using a black-box process in the face of an Internet social revolution that cries out for more collaborative, transparent, “stakeholder-centric” processes. The lecture introduces the graphical path method (GPM) and explains why it is the proper approach to planning and scheduling, and therefore, to project management, in the Internet era. While this lecture focuses on Dr. Ponce de Leon’s experience in our industry, more importantly, it challenges students to recognize that individual driven learning begins at commencement.

How Lifelong Learning Has Shaped My Career

Making 50+ Years of Scheduling Calculus Obsolete

Tishman Distinguished Lecture
Speaker: Gui Ponce de Leon, PhD, PE, PMP, LEED AP
Date: Monday, February 23, 2015

This lecture, which is an integral part of the Tishman Construction Management Program at the University of Michigan, is made possible through a generous gift from Mr. John L. Tishman who served as the Chief Executive Officer at Tishman Realty and Construction Co., Inc. It is intended to promote construction management research, education, and practice among faculty and students. The 2015 speaker will be Dr. Gui Ponce de Leon.

About Dr. Gui

Dr. Gui Ponce de Leon is the founder and CEO of PMA Consultants LLC (PMA), a firm ranked in the top fifty of ENR’s list of Top 100 Construction Management Firms and Top 50 Program Managers since 2005. PMA currently operates 12 offices nationwide. Since 2004, Dr. Ponce de Leon has led the development of PMA’s groundbreaking, patented graphical path method (GPM®) of planning/scheduling and its software embodiments, NetPoint® and NetRisk. Dr. Ponce de Leon’s expertise and leadership in introducing innovative project scheduling methods and techniques will make for a great contribution to the Tishman Distinguished Lecture Series.

Download the Presentation

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GPM® and Forensic Total Float

Bryan Ritch — Wed, 21 Apr 2010 22:00:54 +0000

The critical path method (CPM) is widely used as a project management tool. Basic to CPM is for the planner to draw a project network first, and then to use CPM software to calculate activity dates and total floats, establish the project completion date and locate the critical path. Alas, all is not well in CPM utopia! The moment the planner takes control of activity dates by using constraint dates or resource leveling, total float is reduced (some would say sequestered); and once actual dates are introduced in a CPM network, the analyst loses total floats and the critical path can no longer be calculated left of the data date. The ability to schedule an activity later than its early dates without sacrificing total float, and to determine total floats and the critical path for the as-built portion of a schedule (left of the data date), is solved by the graphical path method (GPM®). This paper describes the float aspects of GPM, while emphasizing the concept of GPM forensic total float and its role in retrospective schedule analysis, whether in updating or forensic scheduling. A compendium of CPM and GPM float concepts is provided for historical context.

Dr. Gui Ponce de Leon, PE, PMP

Presented at PMICOS Annual Conference 2010

Download the Paper

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The History and Future of Time-Scaled Planning

Jillian Mohr — Tue, 05 May 2009 20:37:42 +0000

The human drive to put a picture to the ephemeral aspects of planning is central to the progress of planning through the ages. It is through visualization that the human mind most easily comprehends abstract and spatial frameworks.

In order to properly deal with planning today, as it relates to activities and projects, it may be helpful to first understand how humanity visualizes time. Throughout recorded history mankind has sought to clarify, classify, and visually represent time: from early attempts to create calendars to Einstein’s Theory of Relativity, man has attempted to put concrete definitions to invisible forces in the physical world. How we plan today is informed by how we planned before today and how we visualize time and calendars.

Most projects, regardless of type or size, include some sort of planning or scheduling session early in their lives. The extent of collaboration, content, and scope for such a session can vary dramatically, from something as simple as one person taking a few minutes to detail a few project steps on a piece of paper to something as complex as all project stakeholders participating in a multi-day interactive process to develop a project plan in detail. The authors intend to investigate the historical and current processes used to develop early project plans and to critique current methodology in light of new technologies available now. The authors also will detail what they feel to be the future of interactive/collaborative project planning.

John Zann, PE, LEED AP

Timothy D. Mather, PMP

Presented at the PMICOS Annual Conference 2009

Download the Paper

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Project Planning Using Logic Diagramming Method

Jillian Mohr — Mon, 14 Apr 2008 19:48:34 +0000

This treatise seeks to shine some light back on collaborative network-based planning by advocating the use of LDM (Logic Diagramming Method). LDM is a technique suitable for collaborative planning that is squarely within the reach of project stakeholders who are not necessarily trained schedulers. When used in conjunction with GPM (Graphical Planning Method)1, LDM allows effortless visualization of activity sequences and timing while also offering interrelationships between activities that are more intuitive and versatile for use by non-schedulers than those offered by PDM (Precedence Diagramming Method) or ADM (Arrow Diagramming Method). LDM is a recently unveiled activity-based networking method that modifies and extends ADM to permit PDM logic.

Gui Ponce de Leon, PhD, PE, PMP, LEED AP

Published for AACE International 52nd Annual Conference 2008

Download the Paper

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