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Pushmi-Pullyu (part 1) Dr. Dolittle’s Contribution to Project Planning

I was introduced to project planning and scheduling back in 1994. My mentor is Dean Kyle P.Eng, a graduate of the former Technical University of Nova Scotia (now part of Dalhousie).

He introduced me to a set of methods and tools that were straightforward, easy to apply and very effective. He’d developed a training program along the way, and my partners and I agreed that it would fit well with our current curriculum.

Sometimes, shear naiveté can be a blessing. I thought that his approach was pretty much the accepted way of doing things. I soon learned otherwise.

During the next few years, I came across more ‘accepted’ tools and methods. This was further revealed when I received my Project Management Professional (PMP) certification in 1998.

Over the years I gathered more information. Keeping in mind that project planning/scheduling is the process of coordinating large amounts of information – task descriptions, duration, resources, costs, and dependency relationships… here’s a very brief history:

  • Interestingly, Henry Gantt didn’t originate the Gantt chart. A Polish engineer, Karol Adamiecki, came up with it in 1896, but he didn’t publish it until 1931. Henry’s now ubiquitous chart was introduced during WWI. Its graphical focus is a hierarchy of horizontal bars often cascading downward from upper left to lower right.
  • 1947, Japanese auto maker, Toyota, developed Kanban. These signboards, (now referred to as storyboards or swim lanes) – approached work laid out in vertical columns.
  • 1958 the US Navy, along with Booz Allen & Hamilton of Virginia, developed Program, Evaluation & Review Technique. PERT, along with two other key developments, Work Breakdown Structure (WBS) and Critical Path Method (CPM) eventually created what’s now referred to as a Network or Dependency diagram. This combined both horizontal and vertical workflow patterns found in Gantt and Kanban.
  • Manually prepared network diagrams flourished up until the early 80’s when personal computers came along. The launching of Lotus 123 in January 1983 was a major breakthrough. It paved the way for digital Gantt charts and eventually MS Project, Primavera P6 and many others.
  • In 2001 the IT sector celebrated the Manifesto for Agile Software Development. It combined a wide array of methods and principles, including Kanban and Scrum.
  • Lean Construction evolved from Lean Manufacturing or Just In Time production which began as far back as the 1930’s. Recognizing that construction is a project based production process, the Lean Construction Institute was founded in 1997. It is one of the first acknowledgements of creating plans in the opposite direction… from the end, first.
  • 2004 Dr. Gui Ponce de Leon of PMA Consultants, headquartered in Detroit, introduced an advanced Gantt chart that incorporates a variation of CPM, called Graphical Path Method.

So where does Dr. Doolittle fit into all this anyway? Well, he doesn’t. But the term Pushmi – Pullyu refers to an interesting mystery. Push planning vs. Pull planning

When planning a project, there are two very contrary approaches:
– start planning from the left, or the start of the plan and proceed to the end
– or… start at the right, or the end of the plan and proceed to the start

There have been many terms used for this over the years. Dean uses the terms ‘Forward driven logic’ vs. ‘Objective Driven Logic’. In the 1990’s the concept began to take hold and the term Push Planning and Pull Planning is gradually becoming the ‘accepted’ term. One could argue whether it is any clearer than the other or not. Starting from the ‘End in Mind’ as an overall concept was championed by Steven Covey’s hugely successful book, ‘7 Habits of Highly Successful People’. The entire second chapter is devoted to it. However, he doesn’t go into a lot of detail as to the methods you apply to achieve this habit.

There’s a lot of confusion about this Pull planning alternative. Especially the idea that you only use it if you know the finish date of the project in advance. Given the recent example of the 2020 Olympics starting in July 2021, one could argue that Pull Planning couldn’t or shouldn’t ever be used.

So why the interest? The two most important things Dean taught me are:

  • using a dependency or network diagram for blending simultaneous and sequential workflows
  • apply ‘objective driven logic’ or ‘pull planning’ to determine the logical coordination of work

Like I said earlier, I didn’t know any different, so that’s what I did.

So a question occurred to me a few months back. In my research, I never found any reference as to who came up with this idea of planning ‘backwards’. Especially as it applies to planning complex projects. I didn’t think it was Steven Covey. And Gui Ponce de Leon’s research started in 2004. I’d been using it for a decade by that time.

The obvious solution… ask Dean ‘how this came about’?

A couple weeks later Dean sent me a fascinating letter, some of which I promised to treat with discretion. So (forgive me Dean) here is an edited version:

One of Dean’s first jobs as an engineer was working for Polymer International Corp. out of Tampa Florida. In 1970 they acquired a non-operating plastics plant in Port of Spain, Trinidad. With backing by the local government and some promising new products to produce, Dean was appointed the Project Manager to ‘make it so’.

On his way to Trinidad, he stopped in San Juan, Puerto Rico for a flight change. On the next hop he met up with Tom Ford, a colleague on his way to Caracas, Venezuela. He was coming back from a seminar at Harvard that introduced the relatively new ideas of CPM and PERT.
Between the two of them, Dean was able to sketch out the basics in a notebook. As they were landing, Dean’s response was, “It felt like looking up and seeing a life ring on top of a nearby breaker.”

The next day he moved into his project ‘office’ (a little rough around the edges). Before the cab driver left he asked him to go and find a roll of wallpaper. ‘It doesn’t matter what the pattern is, as long as the back is white’. He mounted it on the wall and with a ball-point pen began putting the project plan together. He used the network diagram method Ford had shown him, however Dean did something different… he started working from the end. The following week, the regional manager for Polymer dropped in. Dean walked him through the plan on the wall. He was so impressed with the layout, that he didn’t hesitate to put his signature to the plan at Dean’s request. (An important insight here)

To my knowledge, this is the first time on record that Pull planning was used, and by my mentor, no less. About 30 years later, while attending my first PMI conference in Baltimore, the Project Management College of Scheduling discussed ‘right to left’ planning.

So what’s the big deal?  ‘Pushmi’ or ‘pullyu’, so what?

I’ll let Dean’s words explain his thinking on this:

“I was desperate to discover what I had to do to succeed with this project. I’m a conscientious guy, and people were depending on me. “What I had to do?”, is what you and I would now call Tasks. I understood my jotted-down list of tasks was incomplete: just items that came to mind and got listed. So, I was aware that I didn’t have a real set of tasks to organize with this newly discovered graphic presentation (PERT/CPM). It was clear that once the network was complete, a schedule could be figured out from it. So, what were the necessary Tasks?

Looking at the newly discovered idea of a CPM diagram as a potential tool to answer that question… it followed that “Dependency” implied “necessary predecessor”. What more did I need to discover all the required tasks and how each was defined? So I marched my way back from the ‘end’ to that distant ‘start’ (working from right to left). If I found all the “necessary predecessors”, I would have a complete task list. Long story short… the construction of the chart not only revealed all the necessary tasks, but they HAD to fit together according to the dependency logic that ultimately drove the creation of the network.”

  • Dean Kyle – June 26, 2021

There’s a lot packed into these few sentences. Stay tuned for part 2, where we’ll look at the subtleties and nuances between these two very different approaches to project planning and scheduling, and why it is so important.

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