Planning problems in construction are accepted and primarily relate to management focus being on control; planning not conceived as a system design; crew level planning being neglected; planning system performance not measured; and planning failures not analysed to identify and act on root causes [3, 5, 7, 8]. A key concept in Lean Construction is the provision of reliable workflow to work-crews to reduce uncertainty in the delivery process [1] and the lookahead function within Last Planner® System (LPS) proactively works to reduce this uncertainty. Relating to ‘make-ready’, the 2020 Benchmark states:

‘…it involves making scheduled tasks ready, and replanning when some scheduled tasks cannot be made ready…. “make ready” is done by identifying and removing any remaining constraints on scheduled tasks in the lookahead period, then breaking scheduled tasks down into operations, and designing those operations. If constraints cannot be removed, the task is rescheduled for a later date when constraints will have been removed.’

The 2020 Benchmark defines a constraint as ‘something that stands in the way of a task being executable or sound.’ Typical constraints on construction tasks are the completion of design or prerequisite work, availability of materials, information, and directives. Screening tasks for readiness is assessing the status of their constraints; removing constraints makes a task sound. It therefore follows that effective constraint identification and management is possibly the most critical function of LPS and in preparing for flow. I wish to show some examples I have come across recently.

Example 1:

The team had been raising constraints, but the graphical data illustrated insufficient time was being allowed for their effective analysis and rectification. Figure 1 illustrates how 91% of the constraints were being raised within 7 days of their needed resolution date. Figure 2 presents the outcome of this with only 25% of constraints being resolved within the required 7 days and 72% of the constraints being resolved late.

Figure 1: Constraints Identification Health

Figure 2: Constraints Removal Health

The problem to be solved was two-fold - firstly the constraints needed to be identified earlier and secondly they needed to be prioritised, ensuring people were always working to resolve the most urgent in sequence of priority. The Scrum framework assisted in the resolution process by:

• prioritisation of the highest value constraints
• ensuring the correct person was working on those constraints
• limiting context switching by focusing on one at a time
• ensuring smaller teams with less communication routes
• daily touchpoints & virtual boards as opposed to single weekly constraint meetings (small and regular releases as opposed to a single weekly release)
• smooth & consistent flow of constraint removals

The progression with the Scrum framework is illustrated in figure 3 with the average constraint resolution time reducing from 17 days to 3.2 days and 95% resolved within 7 days.

Figure 3: Constraint’s resolution improvement with Scrum

Example 2:

The 2020 benchmark (page 28) states; ‘Responsibility for removing constraints is spread throughout the team.’ Figure 4 illustrates a snapshot of 42 open constraints spread across 32 different owners on a single project.

Figure 4: Constraints and ownership spread

Traditionally on the projects a constraints meeting would be conducted weekly, immediately after the make-ready site walk. Freshly identified constraints would be logged on an excel spreadsheet with owners and needed dates assigned. Columns are filterable and constraints are emailed to the owners for their attention. In the case of figure 4, that is 42 constraints communicated to 32 different owners and 32 emails to be picked up, read, and actioned. This is where the decision latency problem exists and where control of the process leaves the site-based project team. As we note in figure 5, two persons on email is a much colder and more ineffective method of communication than two persons on a whiteboard or on a video call.

Figure 5: Communication richness (McCarthy and Monk, 1994)

Referring to the agile principle #6 – ‘The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.’ [4] Of course, in 2022 we now have virtual communication platforms that almost create the ‘face-to-face’ experience. The solution used to improve the decision latency issue in example 2 was to create a virtual Scrum board and over three one-hour scheduled weekly sessions the facilitator could pop in and out to each constraint owner and progress the priority constraints only. This required the 32 constraint owners to keep the one-hour slot free if possible and they would only be on-line on the call for a few minutes when called on to it. This process contributed to the improved constraint resolution duration as illustrated in figure 3, it ensured the priority constraints were being attended to in the right order, and it also protected the constraint owners time as they were addressing the highest value items one at a time as opposed to working on numerous constraints and context switching.

These examples illustrate how a growth mindset and applying agile thinking through the Scrum framework can complement the LPS make-ready and constraints resolution process.

References:

[1] Ballard, G. (2020) The last planner system. In: Lean Construction, pp.45-53. Routledge.

[2] Ballard, G. and Tommelein, I. (2021) 2020 ‘Current Process Benchmark for the Last Planner System of Project Planning and Control’.

[3] Daniel, E. and Pasquire, C. (2017) Last Planner System Path Clearing Approach (LPS-PCA): an approach to guide; clients, main contractors and subcontractors in the implementation of the LPS.

[4] Fowler, M. and Highsmith, J. (2001) The agile manifesto. Software development, Vol. 9, Iss.8, pp.28-35.

[5] Hamzeh, F., Ballard, G., and Tommelein, I. (2009) Is the Last Planner System applicable to design? In: Proceedings of the 17th annual conference of the International Group for Lean Construction, Taipei, Taiwan, pp. 167-176.

[6] McCarthy, J. and Monk, A. (1994) Measuring the quality of computer-mediated communication. Behaviour & Information Technology, Vol. 13, Iss. 5, pp.311-319.

[7] Mossman, A. (2013) Last Planner: 5+ 1 crucial & collaborative conversations for predictable design & construction delivery. The Change Business Ltd., UK

[8] Power, W., Sinnott, D. and Lynch, P. (2021) ‘Evaluating the efficacy of a dedicated last planner system facilitator to enhance construction productivity.’ Construction Economics and Building, Vol. 21, No.3, pp.142-158.