Category Archives: Scheduling

Project planning and scheduling posts

Project scheduling Update

1. A new paper looking at the origins of CPM has been uploaded to our PM-History page – http://www.mosaicprojects.com.au/Mag_Articles/P037_The_Origins_of_CPM.pdf looks at where the concepts that evolved into CPM and PERT originated. All of our papers can be found at: http://www.mosaicprojects.com.au/PM-History.html

2.  The PMI members’ only Scheduling Conference 2017 is going to be great! Over 17,000 people are registered already – I’m the last speaker for the day (which means I only have to get up at 6:00am Australian time to participate…..) More information see: https://www.projectmanagement.com/events/356123/PMI-Scheduling-Conference-2017  My topic looks at the effect of the data generated by BIM, drones and other technology on controls.

3.  PGCS Canberra is on in early May – too good to miss, see: http://www.pgcs.org.au/

Setting up a project controls system for success

A couple of hour’s hard thinking can make the difference between project success and failure!  Far too many projects are simply started without any real thought as to the best strategy for delivery and what control systems are really needed to support the management of that delivery – one size does not ‘fit-all’ and simply repeating past failures creates more failures.  Similarly, far too many control systems are implemented that simply generate useless paperwork (frequently to meet contractual requirements) when what’s needed is effective controls information.

Remembering that all project controls documents have to be used and maintained to be useful; the three key thinking processes needed to help build project success are:

  • First the big question – how are we going to do the work to maximise the opportunity of success and optimise risk??  This is a strategic question and affects procurement as much as anything – off-site assembly needs a very different approach to on-site assembly. This does not need a complicated document but the strategy does need to be agreed; see: www.mosaicprojects.com.au/WhitePapers/WP1038_Strategy.pdf
  • From the strategy, the project management team structure can be designed to best manage the work as it will be accomplished and these people (or at least the key people) can then contribute to the planning process. Pictures are as useful as anything to define the overall flow of the work; see: www.mosaicprojects.com.au/WhitePapers/WP1039_Project_Planning.pdf.
  • Once you know the way the work will be accomplished and the overall flow/sequence of the work you are now in a position to plan the project controls function aiming to apply the minimum amount of ‘controls’ necessary to be effective.  Excessive controls simply waste money and management time. My approach is always to do a bit less then I think may be needed because you can always add some additional features if the need eventuates – it Is nearly impossible to remove controls once they have been implemented.
  • Then you can develop the schedule and other control tools needed for effective management working within the framework outlined above.

This area is what PMI call Schedule strategy and Schedule planning and development. Getting this ‘front-end’ stuff right is the best foundation for a successful completion of a project; this is the reason these elements of project controls have a strong emphasis in the PMI-SP exam.

Conversely, stuffing up the strategy in particular, means the project is set up to fail and implementing control systems that do not support the management structures within the project simply mean the controls people are wasting their time and the time of everyone they engage with.

However, creating a project that is based on a sound strategy supported by a useful project controls system will require some cultural changes:

  • The project manager and project executive will need to take some time to look at strategic options and develop an effective delivery strategy.
  • The organisation and client will need to allow the project controls professionals to work through the challenges of developing a ‘light-but-effective’ controls system and then review/approve the system – this is more difficult than simply requiring every project to comply with some bloated standard controls process that no one uses (except for claims) but should deliver massive benefits.
  • The organisation will need skilled project controls professionals……….
  • And the project management team will need to be willing to work with and use the project controls.

The problem is easy to outline – fixing it to enhance the project success rate is a major challenge.

There’s a great Scheduling party in Atlanta this May!

Why not attend the Project Management College of Scheduling (PM-COS) annual conference either as a speaker or delegate and collect your ‘ticket to project success’?

pmcos2017

Some of the reasons for joining us at The Ritz-Carlton, Atlanta include:

  • CPM Scheduling has been around for more than fifty years.  How much is art?  How much is science?  Help us decide.
  • Network with schedule professionals from around the globe including many of the top practitioners and experts in the field.
  • Learn tips from experts such as the role that case law plays in schedule delay analysis.
  • Help us address important issues facing the scheduling profession today and how to resolve them as we move forward.
  • Attend presentations and panel discussions to learn the recent developments in the profession and how to implement them on your projects.

For more information and to register, visit us at www.pmcos.org!

Free, Exclusive Project Scheduling Virtual Event for PMI Members

pmi-virtual-scheduling

PMI members are entitled to register and attend this member-only event on the 29th March (9:00 am to 5:00 pm ET) for free! It is the perfect way to learn what’s new in project scheduling and network with PMI members across the globe. This year we are talking about how to tackle project scheduling challenges in a changing profession.

My presentation is focused on Projects Controls Using Integrated Data – The Opportunities and Challenges.   The presentation is focused on the practical and ethical challenges posed by integrated information management tools such as BIM and ‘drones’ in the construction/engineering industries and how this affects the work of project controls professionals.

To register go to: https://www.projectmanagement.com/events/356123/PMI-Scheduling-Conference-2017

If you are not a PMI member (or cannot make the date) watch this space.

 

The origins of PERT and CPM – What came before the computers!

The development of PERT and CPM as Mainframe software systems starting in 1957 is well documented with contemporary accounts from the key people involved readily available.  What is less clear is how two systems developed contemporaneously, but in isolation, as well as a number of less well documented similar systems developed in the same timeframe in the UK and Europe came to have so many similar features.  These early tools used the ‘activity-on-arrow’ (AoA or ADM) notation which is a far from obvious model.  Later iterations of the concept of CPM used the ‘precedence’ notation which evolved from the way flow-charts were and are drawn.

stockpile

One obvious connection between the early developments was the community of interest around Operation (or Operational) Research (OR) a concept developed by the British at the beginning of WW2.  OR had developed to include the concept of linear programming by the mid-1950s which is the mathematical underpinning of CPM, but while this link explains some of the cross pollination of ideas and the mathematics it does not explain terms such as ‘float’ and the AoA notation (for more on the development of CPM as a computer based tool see http://www.mosaicprojects.com.au/PDF_Papers/P042_History%20of%20Scheduing.pdf).

A recent email from Chris Fostel, an Engineering Planning Analyst with Northrop Grumman Corporation (CFostel@rcn.com) appears to offer a rational explanation.  I’ve reproduced Chris’ email pretty much verbatim below – the challenge posed to you is to see if the oral history laid out below can be corroborated or validated.  I look forward to the responses.

Chris’ Oral History

quartermaster_corpsI was told this story in 1978 by a retired quartermaster who founded his own company after the War to utilize his global contacts and planning skills.  Unfortunately the individual who told me this story passed away quite a few years ago and I’m not sure any of his compatriots are still alive either.  Regardless, I thought I should pass this along before I join them in the next life.  I do not wish to minimize the work of Kelly and Walker. They introduced critical path scheduling to the world and formalized the algorithms.  They did not develop or invent the technique.

The origin of critical path scheduling was the planning of the US Pacific Island hopping campaign during World War II.  The Quartermaster Corps coordinated orders to dozens if not hundreds of warships, troop ships and supply ships for each assault on a new island.  If any ships arrived early it would alert the Japanese of an imminent attack.  Surprise was critical to the success of the island hopping campaign.  The US did not have enough warships to fight off the much larger Japanese fleet until late in the war. Alerting the Japanese high command would allow the Japanese fleet to intercept and destroy the slow moving US troop ships before they had a chance to launch an attack. 

Initially the quartermasters drew up their plans on maps of the pacific islands, including current location and travel times of each ship involved.  The travel times were drawn as arrows on the map.  Significant events, personnel or supplies that traveled by air were shown as dashed lines hopping over the ship’s arrows.  The quartermasters would then calculate shortest and longest travel times to the destination for all ships involved in the assault. The plans became very complicated.  Many ships made intermediate stops at various islands to refuel or transfer cargo and personnel.  The goal was to have all ships arrive at the same time.  It didn’t take the quartermasters long to realize that a photograph of the planning maps would be a devastating intelligence lapse.  They started drawing the islands as identical bubbles with identification codes and no particular geographical order on the bubble and arrow charts. These were the first activity on arrow critical path charts; circa 1942. 

The only validation I can offer you is that by now you should realize that activity on arrow diagrams were intuitive as was the term ‘float.’  Float was the amount of time a particular ship could float at anchor before getting underway for the rendezvous.  Later when the US quartermasters introduced the technique to the British for planning the D-Day invasion the British changed float to “Slack”, to broaden the term to include air force and army units which did not float, but could ‘slack off’ for the designated period of time. 

You will not find a written, dated, account of this story by a quartermaster corps veteran.  Critical path scheduling was a military secret until declassification in 1956.  In typical fashion, the veterans of WWII did not write about their experiences during the War.  No one broke the military secrecy.  After 1956 they were free to pass the method on to corporate planners such as Kelly and Walker.  A living WWII Quartermaster veteran, should be able to provide more than my intuitive confirmation.

This narrative makes sense to me from a historical perspective (military planning has involved drawing arrows on maps for at least 200 years) and a timing perspective.  Can we find any additional evidence to back this up??  Over to you!

The future of project controls

Last week I participated in two PUXX panel discussions in Perth and Sydney focused on predicting the influence of technology on project controls.  The range of subjects covered ranged from drones and remote monitoring to virtual reality.

Many of the topics discussed offered better ways to do things we already do, provided we can make effective use of the data generated in ever increasing quantities – significant improvements but essentially ‘business-as-usual’ done better. The aspect I want to focus on in this post is the potential to completely reframe the way project schedules are developed and controlled when existing ‘gaming technology’ and BIM are synthesised.

The current paradigm used for critical path scheduling is a (dumbed-down) solution to a complex set of problems required to allow the software to run on primitive mainframe computers in the late 1950s – the fundamentals have not changed since! See: A Brief History of Scheduling.

The underlying assumption is a project consists of a set of activities each with a defined duration and depending on the logical relationship between the activities, some are ‘critical’ others have ‘float’.  The basic flaw in this approach can be demonstrated by looking at the various options open to a schedule to define the work involved in 3 simple foundations involving excavation and mass concrete fill.

schedule-options

All four of the above options above are viable alternatives that may be chosen by different schedulers to describe the work using CPM, and none of them really describe what actually happens. The addition of more links would help but even then the real situation which is one resource crew visits three locations in turn and excavates the foundations, a second crew follows and places the concrete with some options for overlapping, parallel working and possibly synchronising the actual pouring of all three foundations on the same day…….. Optimising the work of the crews is the key to a cost effective outcome and this depends on what follows their work.  For more on resource optimisation see: www.mosaicprojects.com.au/Resources_Papers_152.html. Advances in computer software offer the opportunity to develop a new way of working.

The starting point for the hypothesis outlined I this post is 4D BIM (Building Information Modelling). Last month I was in London working on the final edits to the second edition of the CIOB’s book, Guide to Good Practice in the Management of Time in Complex Projects (due for publication in 2017 as The Management of Time in Major Projects). One of the enhancements in the second edition is an increased focus on BIM. To assist our work a demonstration of cutting edge 4D BIM was provided Freeform.

Their current capabilities include:

  • The ability to model in real time clashes in working space provided the space needed for each crews work is parameterised. Change the timing of one work crew and the effect on others in a space is highlighted.
  • The ability to view the work from any position at any time in the construction process; allowing things such as a tower crane driver’s actual line of sight to be literally ‘seen’ at different stages of the construction.
  • The relatively normal ability to import schedule timings from a range of standard tools to animate the building of the model, and the ability to feedback information derived from processes such as the identification of clashes in the use of working space using
  • The space occupied by temporary works and various pieces of equipment can be defined and clashes with permanent works identified over time.
  • Finally the ability for a person to see and move around within the virtual model using the same type of 3D virtual reality goggles used by many gaming programmes. The wearer is literally immersed in the model.

For all of this in action on a major rail project see: https://www.newcivilengineer.com/future-tech/pushing-the-limits-of-bim/10012298.article

Moving into the world of game playing, there are many different games that allow players in competition, or collaboration, to ‘build’ cities, empires, fortifications, farms, etc. These games know the resources available to the players and how many resources will be required to construct each new element in the game – if you don’t have the resources, you can’t build the new asset.

Combining these two concepts opens up the possibility for a completely new approach to scheduling physical projects that involve the deployment of resources to physical locations to undertake work. The concept of location-based scheduling is not new, it was used in the 1930s to construct the Empire State Building (see: Line of Balance) and is still widely used.  For more on location-based scheduling see: Location-Based Management for Construction: Planning, Scheduling, and Control by Prof. Russell Kenley.

How these concepts tie into BIM starts with the model itself.  A BIM model consists of a series of parameterised objects. Each object can contain data on its size, weight, durability, cost, maintainability, carbon footprint, etc. As BIM develops many of these objects will come from standard libraries created by suppliers and subcontractors. Change an object, for example, replace windows from manufacturer “A” with similar Windows from manufacturer “B” and the model is update and potential issues with sizes, fixings and waterproofing can be identified. It is only a small step from this point to add parameters related to the resources needed to undertake the work of installation.

With this information and relatively minor enhancements to current BIM capabilities, once the engineering model is reasonably complete a whole new paradigm for planning work opens up.

4d-vr

To plan the work the ‘planning team’ put on their virtual reality headsets and literally ‘walk’ onto the site.  As they start to locate temporary works and begin the building process the model is tracking the use of resources and physical space in real time. The plan is developed based on the embedded parameters in the fully integrated 3D model.

Current 4D imports a schedule ‘shows you’ the effect.  Using the proposed gaming approach and parameterized objects you can literally build the project in the virtual space and either see the consequences on resource loading or be limited by resource availability.  A whole bunch of games do this already, add in existing clash detection capabilities (but applied to workers using the space) and you change the whole focus of planning a project. Decisions can be made to adjust the size of resource crews and the flow of work can be optimised to balance the competing objectives of cost efficiency, time efficiency and resource optimisation.

The proposed model is a paradigm shift away from CPM and its arbitrary determination of activities and durations to a process focused on the smooth flow of resources through work areas. The computational base will be focused on resource effectiveness and resource utilisation. Change ‘critical path’ to ‘critical resources’, eliminate the illusion of ‘float’ but look for underutilised resources and resource waiting time. To optimise the work, different scenarios can be stored, replayed and edited – the ultimate ‘what-if’ experience.

The concept of schedule density ties in with this approach nicely; initial planning is done for the whole project at the ‘low density’ level with activity durations of several weeks or months setting out the overall ‘time budget’ for the project and establishing the strategic flow of work.  As the design improves and more information becomes available, the schedule is enhanced first to ‘medium density’ and then to ‘high density’. The actual work is controlled by the ‘high density’ part of the schedule. For more on ‘schedule density’ see: www.mosaicprojects.com.au/WhitePapers/WP1016_Schedule_Density.pdf.

Where this concept gets really interesting is in the control of the work.  The medium and high density elements of the schedule are built using the same ‘virtual reality’ process as the overall schedule, therefore each object in the overall BIM model can include data on the resources allocated to the work, the sequence of work and the time allowed. Given workers on BIM-enabled projects already use various PDAs to access details of their work, the same tablet or smart device can be used to tell the workers their next job and how long that have to complete it. When they complete the task, updating the BIM model with that progress information updates the schedule, tells the crew their next job and tells the next resources planned to move into the area that the space is available. The schedule and the 3D model are the same entity.

Similarly, off-site manufacturing and design lead-times can be integrated into the dataset.  Each manufactured item can have its design, manufacture and transport and approval times associated with the element making the development of an off-site works / procurement schedule a simple process to extract the report once the schedule is set.  Identifying delays in the supply chain and dealing with changes in the timing of installation become staigtforward.

When inevitable problems occur, the project management team have the ideal tool to work through solutions and determine the optimum way forward, as soon as the new schedule is agreed, the BIM model already holds the information.

One of the key concepts in ‘schedule density’ is that any work planned for the short-term future has to be based on the actual performance of the crews doing the work. In a BIM enabled scheduling system this can also be automated. The work content of each activity is held in the model as is the crew assigned to the work. As soon as the work crew’s productivity can be measured, the benchmark values used in the original planning can be updated with real data. Where changes in performance are needed to deal with slippages and productivity issues these can be properly planned and incorporated into the schedule based on when the implemented changes can be expected to occur.

I’m not sure if this is BIM2 or BIM++ but these ideas are not very far in advance of current capabilities – all we need now is a software developer to take on the ideas and make them work.

These concepts will be harder to apply to ‘soft projects’ but the planning paradigms in soft projects have already been shaken up by Agile. But integrating 3D modelling with an integrated capability for real 4D interaction certainly seem to make sense for projects where the primary time management issue is the flow of resources in the correct sequence through a defined series of work locations in three dimensions.   What do you think???

Critical confusion – when activities on the critical path don’t compute……

The definition of a schedule ‘critical path’ varies (see Defining the Critical Path), but the essence of all of the valid definitions is the ‘critical path’ determines the minimum time needed to complete the project and either by implication or overtly the definitions state that delaying an activity on the critical path will cause a delay to the completion of the project and accelerating an activity will (subject to float on other paths[1]) accelerate the completion of the project.

A series of blog posts by Miklos Hajdu, Research Fellow at Budapest University of Technology and Economics, published earlier this year highlights the error in this assumption and significantly enhances the basic information contained in my materials on ‘Links, Lags and Ladders’ and our current PMI-SP course notes.  The purpose of this post is to consolidate all these concepts into a single publication.

The best definition of a critical path is Critical Path: sequence of activities that determine the earliest possible completion date for the project or phase[2].  This definition is always correct.  Furthermore, in simple Precedence networks (PDM) that only use Finish-to-Start links, and traditional Activity-on-Arrow (ADM) networks the general assumption that increasing the duration of an activity on the critical path delays the completion of the schedule and reducing the duration of an activity on the critical path accelerates the completion of the schedule holds true.  The problems occur in PDM schedules using more sophisticated link types.  Miklos has defined five constructs using standard PDM links in which the normal assumption outlined above fails. These constructs, starting with the ‘normal critical’ that behaves as expected are shown diagrammatically below[3].

Normal Critical

The overall project duration responds as expected to a change in the activity duration.

1 Normal critical

A one day reduction of the duration of an activity on the critical path will shorten the project duration by one day, a one day increase will lengthen the project duration by one day.

Reverse Critical

The change in the overall project duration is the opposite of any change in the activity duration.

2 Reverse Critical

A one day reduction of the duration of Activity B will lengthen the project duration by one day, a one day increase will reduce the project duration by one day.

Neutral Critical

Either a day decrease or a day increase leaves the project duration unaffected. There are two variants, SS and FF:

3 Neutral 1

3 Neutral 2

In both cases it does not matter what change you make to Activity B, there is no change in the overall duration of the project.  This is one of the primary reasons almost every scheduling standard requires a link from a predecessor into the start of every activity and a link from the end of the activity to a successor.

Bi-critical Activities

Any change in the duration of Activity B will cause the project duration to increase.

4 Bi-critical

A one day reduction of the duration of Activity B will lengthen the project duration by one day, a one day increase will lengthen the project duration by one day.  Bi-critical activities depend on having a balanced ladder where all of the links and activities are critical in the baseline schedule. Increasing the duration of B pushes the completion of C through the FF link.  Reducing the duration of B ‘pulls’ the SS link back to a later time and therefore delays the start of C.  The same effect will occur if the ladder is unbalanced or there is some float across the whole ladder, it is just not as obvious and may not flow through to a delay depending on the float values and the extent of the change.

Increasing Normal Decreasing Neutral

An increase in Activity B will delay completion, but a reduction has no effect! There are two variations on this type of construct.

5 Increasing Normal Decreasing Neutral 1

5 Increasing Normal Decreasing Neutral 2

A one day increase in the duration of Activity B will increase the project duration by one day, however, reducing the length of Activity B has no effect on the project’s duration.

Increasing Neutral Decreasing Reverse

An increase in Activity B has no effect, but a reduction will delay completion! Again, there are two variations on this type of construct.

6 Increasing neutral decreasing reverse 1

6 Increasing neutral decreasing reverse 2

A one day increase in the duration of Activity B has no effect on the project’s duration, however, reducing the length of Activity B by one day will increase the project duration by one day.

Why does this matter?

The concept of the schedule model accurately reflecting the work of the project to support decision making during the course of the work and for the forensic assessment of claims after the project has completed, is central to the concepts of modern project management.  Apart from the ‘normal critical’ construct, all of the other constructs outlined above will produce wrong information or allow a claim to be dismissed based on the nuances of the model rather than the real effect.

Using most contemporary tools, all the planner can do is be aware of the issues and avoid creating the constructs that cause issues.  Medium term, there is a need to revisit the whole function of overlapping activities in a PDM network to allow overlapping and progressive feed to function efficiently.  This problem was solved in some of the old ADM scheduling tools, ICL VME PERT had a sophisticated ‘ladder’ construct[4].  Similar capabilities are available in some modern scheduling tools that have the capability to model a ‘Continuous precedence relationship[5]’ or implement RD-CPM[6].


[1] For more on the effect of ‘float’ see: http://www.mosaicprojects.com.au/PDF/Schedule_Float.pdf

[2] From ISO 21500 Guide to Project Management,

[3] The calculations for these constructs are on Miklos’s blog at: https://www.linkedin.com/in/miklos-hajdu-a1418862

[4] For more on ‘Links, Lags and Ladders’ see: http://www.mosaicprojects.com.au/PDF/Links_Lags_Ladders.pdf

[5] For more on continuous relationships see:  http://www.sciencedirect.com/science/article/pii/S1877705815031811

[6] For more on RD-CPM see: http://www.mosaicprojects.com.au/WhitePapers/WP1035_RD-CPM.pdf