Other related sections of the PMKI:
The science of ‘scheduling’ as defined by Critical Path Analysis (CPA) has its origins in 1956/57 Kelly and Walker started developing the algorithms that became the ‘Activity-on-Arrow’ or ADM methodology for DuPont. The program they developed was trialed on plant shutdowns in 1957 and the first paper on critical path scheduling was published in 1958. The PERT system also used ADM and was developed at around the same time but lagged CPM by 6 to 12 months (although the term ‘critical path’ was invented by the PERT team). Later the Precedence (PDM) methodology was published by Dr. John Fondahl in 1961 as a ‘non-computer’ alternative to CPM. Arguably, the evolution of modern project management is a direct consequence of the need to make effective use of the data generated by the schedulers in an attempt to manage and control the critical path [see: The Origins of Modern Project Management].
The evolution of scheduling closely tracked the development of computers. The initial systems were complex mainframe behemoths, typically taking a new scheduler many months to learn to use. These systems migrated to the ‘mini computers’ of the 1970s and 80s but remained expensive thereby encouraging the widespread use of manual scheduling techniques, with only the larger (or more sophisticated) organizations being able to afford a central scheduling office and the supporting computer systems. The advent of the ‘micro computer’ (ie, personal computer, or PC) changed scheduling for ever. The first commercial software for this class of computer was developed by Micro Planning Services in the UK running on an Apple II. Micro Planner v1.0 was released in 1980 after 14 months development [see more on the history of Micro Planner].
The first IBM PC was launched in 1981; although the definitive IBM XT was not launched until 1983. ‘Windows’ type operating systems became available in 1984 (Apple Macintosh) with ‘Windows v1.0’ (Microsoft) launched in November ‘85. The rapid spread of relatively cheap, easy-to-use’ PCs spawned dozens (if not hundreds) of PC based scheduling systems including TimeLine, CA Superproject and Primavera. Most of the dominant scheduling software tools available today emanate from this period. By way of example, Primavera was founded in May 1983, the original software being converted from a mainframe batch entry system. Today Primavera is arguably the dominant ‘high end’ project scheduling tool world wide. The evolution of PC based scheduling moved project controls from an environment where a skilled cadre of schedulers operating expensive systems made sure the schedule was ‘right’ (and the organization ‘owned’ the data) to a situation where anyone could learn to drive a scheduling software package, schedules became ‘islands of data’ sitting on peoples’ desktops and the overall quality of scheduling plummeted. Current trends back to ‘Enterprise’ systems supported by PMOs seem to be redressing the balance and offering the best of both worlds. From the technology perspective, information is managed centrally, but is easily available on anyone’s desktop via web enabled and networked systems. From the skills perspective PMOs are re-developing career paths for schedulers and supporting the development of scheduling standards within organizations.
PP: The Origins of Schedule Management. The concepts used for project schedule management have very deep roots. This paper traces the development of the concepts most project managers take for granted including bar charts and critical path schedules from their origins (which are far earlier than most people think) through to the modern day.
PP: A Brief History
of Scheduling. This paper tracks the
development of scheduling from the emergence of 'bar
charts' at the end of the 18th Century through to present
times and looks at the way the evolving technology has
changed the way projects are scheduled and managed.
Art: A Brief History of Scheduling (short summary).
The 1910 Schürch barchart referenced in the 'History of Scheduling' paper: These are fully developed, sophisticated project control tools in use many years before the work of Henry Gantt was published.
PP: The Origins of Bar Charting. This paper looks at the ancient Greek and Egyptian origins of the concepts used by both Priestly and Playfair as a starting point to develop their charts which in turn led to the development of the modern bar chart by the late 1800s.
Art: The origins of PERT and CPM. This paper looks at ‘what came before the computers’, including the origins of the mathematics and drawing styles used in PERT and critical path schedules. See also The Origins of CPM, PDM and PERT Schedules.
The Origins of Hammocks and Ladders. Hammock
and Ladders are activity types that were developed in the
period 1961 to 1965. This paper outlines the development
of these useful scheduling assets an differentiates
Hammocks from LOE and Summary activities.
See also extracts from the ICL 1900 PERT manual Circa. 1968.
What scheduling looked like in 1979 - The development of Micronet for the Apple PC. An analysis only required 6 hours..... See: https://www.praxisframework.org/en/resource-pages/dooley-what-scheduling-looked-like-in-79
Strangely, for a relatively simple concept supported by an equally simple diagram, it is generally accepted the concept of the work breakdown structure (WBS) was not developed until 1957. I find this strange given the similarity between a WBS diagram, an Organization Chart and a Flow Chart.
The Scottish-American engineer Daniel McCallum (1815–1878) is credited for creating the first organizational charts of American business around 1854. While McCallum’s diagram is rather artistic, more WBS like charts were developed early in the 20th century (although not widely used).
Click on either chart to download a larger version.
Footnote: The Tabulating Machine Co. (above) was
one of the companies that merged to become IBM.
Click to open a brief timeline provided by Dr. Mihail Sadeanu.
One of the earliest diagrams of a breakdown structure I've been able to find is from a 1909 book Construction Cost Keeping and Management. The book is discussed in the section on The History of Earned Value and Cost Controls below.
A few years later, Process Charts were developed and publicized by Frank and Lillian Gilbreth in their 1921 presentation to The American Society of Mechanical Engineers. Process Charts morphed into Flow Charts relatively quickly and were considered normal business diagrams well before the concept of a ‘flow chart’ was used to underpin the PDM network notation developed by Dr. John W Fondahl in 1962.
While the roots of a WBS chart may well be found in the various forms of chart outlined above, the development of the WBS concept appears to have occurred as part of the Program Evaluation and Review Technique (PERT). While the term "work breakdown structure" was not used in by the PERT team, the first implementation of PERT did organize its tasks into product-oriented categories (see more on the development of PERT).
In June 1962, DoD and NASA published a document describing the PERT/COST system which defined the structure and use of the WBS, nothing much has changed since:
The next significant development in WBS was the publication of MIL-STD-881 on 1 November 1968 by the USA Dept. of Defense. This was followed by MIL-STD-881A on 25 April 1975; this standard has been progressively updated since. Download a copy of MIL-STD-881A.
Numerous other standards for the creation and use of WBS followed; including DEF(AUST)5664 in 1995, PMI's Practice Standard for WBS in 2001 (WBS was a core component of the PMBOK for many years prior), and ISO 21511 Work breakdown structures for project and programme management in 2018.
Prs: Earned Value Management – Past, Present & Future. An overview of the development of EVM, the current state of development, and some thoughts about using EVM in a future integrated design and controls system.
For a USA timeline see: http://www.mycpm.org/what-is-evm/the-history-of-evm/
The 1964 Evaluation of PERT/Cost. This original paper looks at the challenges of assessing the business value of using the PERT/Cost system following its introduction in 1963/64. The report findings are still relevant!
Prs: Seeing the Road Ahead - the challenge of communicating schedule data. This presentation looks at the challenges faced by project controls professionals, both in the past and present times, to communicate sophisticated information to other members of the project team and their stakeholders and some of the tools and processes they used.
Blg: Predicting Completion. When did managers start using data to calculate project completion times and costs? It would appear to be a development of the 1950s.
Blg: The three phases of project controls. The reactive, empirical and predictive phases of project controls (see also Predicting Completion).