In March 2023 the PGCS hosted a half-day international webinar looking at the development of Earned Schedule in the 20 years since its initial publication by Walt Lipke in 2003. An article reviewing this significant milestone event written by Robert Van De Velde has been published in the May 2023 edition of PM World Journal, read Robert’s review at: PGCS Webinar: Earned Schedule at 20 Years–A Recap
The next major event on the PGCS calendar, supported by Mosaic Project Services, is the 2023 Symposium, to be held in Canberra from 22nd to 24th August, details are at: https://www.pgcsymposium.org.au/ it not too late to be part of this exciting event.
It seems nothing is fixed if you look closely enough, a few months ago we posted The Planning Paradox How much detail is too much? Which looked at the ‘coastline paradox’, which in summary states, the smaller your measurement unit, the longer a coastline becomes. This post is a corollary – the fact a reference point moves does not invalidate the reference.
Every height in the in the Great Britain is stated as a height above (or below) the Ordnance Datum Newlyn (ODN) – Ireland uses a different datum. The ODN is defined as the mean sea level as recorded by the tidal gauge at Newlyn in Cornwall between 1915 and 1921, and is marked by a brass bolt fixed to the harbour wall in Newlyn.
(a) The brass bolt benchmark (OS BM 4676 2855) which is located in the Tidal Observatory and from which the ODN national datum is defined as being 4.751 m below the mark, and (b) the cover of the historic mark.
While ODN was a measurement of mean sea level in 1915-1921, it is important to recognize that mean sea level has risen since then, so it is best to think of the ODN as an arbitrary height reference point that has been used for the past 100 years rather than a reflection of the actual current mean sea level.
Given the Cornish peninsula is made of solid granite, as is the harbour wall, Britain has a fixed reference point for all levels, so everything should be good….. or is it?
The problems start when you measure heights from space using accurate GPS, these measurements show that the whole Cornish Peninsular rises and falls by several centimeters twice every day in response to the tidal loading caused by the very high tidal range in the region moving gigatons of water in and out of the English and Bristol Channels. While moving up and down by as much as 13 cm sounds dramatic, and is measurable, the deflection is very small when compared to the scale of the earth. In contrast, an error of 13 cm in an engineering survey would be very significant.
The effect of tidal loading is not restricted to Cornwall, an academic paper by P. J. Clarke and N. T. Penna has determined ocean tide loading (OTL) affects all parts of the British Isles to varying degrees, causing peak-to-peak vertical displacements of up to 13 cm in South-West England (Cornwall), reducing to a few millimeters as you move further inland. OTL also causes lateral displacements as the earth’s crust flexes, these are typically around one-third of the magnitude of vertical displacements.
All of this flexing means there will be measurable differences between surveys done using the Global Navigation Satellite System (GNSS) and those based on the Ordnance Survey datums across the UK, And the difference will change continually throughout the day. The differences are calculable but which reference system is correct? Most modern survey equipment uses GNSS, but the location of everything shown on maps and plans is based on measurements derived from the Ordnance Survey datums.
The first question is which reference point really matters for what you are doing. Most terrestrial surveys are positioning things on land, property boundaries, foundation levels, etc. Given all of the ‘land’ in a location will be moving more-or-less as a single unit, measurements from the datums fixed to the land are usually going to be the most useful. It is only if you are operating at a global level, the GNSS data becomes more useful. Surveyors the world over use equipment based on GNSS (it makes their job much easier), but typically reference their equipment’s datum back to a local survey mark – they calculate the relative differences based on this fixed reference point – the fact everything is moving becomes irrelevant.
So, what has all this got to do with project controls? I would suggest two things:
First excessive detail is the enemy of useful information. When you are using a map on a hike, you don’t care if the reference points a moving a few centimeters, you just want to know how many miles to the next pub!
Second, you need a valid reference point and metric. If you are looking a measuring ‘velocity’ in a project using Scrum, or productive effort in an engineering facility, using hours of effort are likely to be more meaningful than the overall cost which can be distorted by the variable pay rates earned by different people. But, if you are measuring the overall viability or profitability of a project, then the overall costs do matter.
The answer to this question depends on how you perceive success and failure. Our latest article published in the May PM World Journal offers several possible alternatives.
However, reflecting on data in the article shows a worrying trend:
Using traditional measures, 80% of organizations do appear to have project failure rates averaging around 80%, but this is not the perception of most managers in those organizations.
Organizations that manage projects successfully achieve a significant cost-benefit over those that do not. Poor project delivery is directly linked to higher project costs.
Therefore, the long sought after answer to Cobb’s Paradox can at last be unveiled:
If 75% of the managers in poorly performing organizations believe their projects are being delivered successfully, they have no reason to invest in improving project delivery capability. Outsiders may see project failure and know how to improve the organization’s systems to prevent future failures, but the majority of the managers in the organization cannot see, or will not see, there is a problem that needs fixing. The answer to Cobb’s paradox: ‘We know why projects fail, we know how to prevent their failure — so why do they still fail?’ is the responsible managers do not perceive their projects as failing and therefore will not invest in solving a problem they cannot, or will not, acknowledge. Changing this flawed perception is a major governance challenge.
Over several years we’ve been posting on the evolution of calendars over the past 6000+ years and in particular the sophistication of the Antikythera mechanism[1] in predicting the synodic periods[2] of the major planets. For these papers and articled see:
It now seems the ancient Mayan civilization were equally sophisticated. Recently, researchers at Tulane University in Louisiana have solved the mystery of the 819-day calendar used by ancient Mayans from at least the 5th century BCE – it matches the planetary cycles of all planets that might have been visible to astronomers of the civilization over a 45-year span!
The synodic period of Mercury (117 days) is 1/7th of 819.
Seven synodic periods of Mars (780 days) exactly match 20 cycles of the 819 day calendar
Venus needs seven synodic periods (584 days each) to match five counts of 819.
Jupiter takes 39 synodic periods of 399 days to match 19 counts of 819.
Saturn has 13 synodic periods of 378 days in six 819-day counts.
These correlations are too complex to be caused by random chance. Therefore, it is reasonable to assume the ancient Mayans had created a large calendar system that could be used to predict the synod periods of all visible planets. The number of observations over multiple generations needed to develop a calendar of this sophistication is mind-blowing. But the fact similar processes occurred in the Middle East, Mesoamerica, and in all probability, the Indus Valley and China suggests a high level of organizational ability in these ancient societies. If you can spend several hundred years accumulating the data needed to create this type of calendar, and then have the tools needed to interrogate the data and draw conclusions, building the odd pyramid, canal, or city is a relatively short-term endeavor.
[2] Synodic period, the time required for a body within the solar system, such as a planet, the Moon, or an artificial Earth satellite, to return to the same or approximately the same position relative to the Sun as seen by an observer on the Earth.
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