When you work wiht multipel subcontract tradesmen for e.g. brickwork, plastering, painting, window frame isntall, glazing etc is it better to finish one room and then start the next, or to finish one task across all rooms and then start the next?
When each task works at a different rate how do you balance the team sizes to decide whether one taks needs multiple teams working on several rooms simultaneoulsy
How much does location influence the crtical path, float, and optimum resourcing?
How much time and money is lost if no work is happening in room 2 because the tradesman is till working on room 1?
How Owners Benefit from Location-Based Management Systems (LBMS)
Scheduling methods often fall short because they do not transparently show (1) that all possible ways to compress the schedule have been used in the contractor’s schedule nor (2) how risky is the schedule
During production project engineers monitor the critical path and floatand compress durations on the critical pathbut often this is done with good intention but without any realistic plan to achieve this compression, nor with timely analysis and coordination with supply chain, resource planning and sub contractor ability to deliver.
When project durations are based on a detailed understanding of the scope or resources needed, this manipulation does notadd more value to management and is often pointless. ‘We are delayed now but we will take some (undefined) catch up action later’. Problems get pushed to the end of the project and there is wishful thinking about the ability to catch up schedules.
Actual Production progress should give early warning signals to Owners and CM’s that something must be done to restore production. All control actions should be explicable in detail with quantities, resources, and production rates instead of just best guess, changing durations.
LBMS before the Start of Construction
Optimized production rates are used in the buy-out of subcontractors, and it is extremely difficult and costly to change the total duration after subcontractors are bought out. Therefore, schedule optimization and compression should happen before buy-out.
It is extremely important that work is planned to be continuous. Cascading delays during production happen because of discontinuous work -the starts and stops of subcontractors. Every discontinuity increases the probability that the schedule will not be executed as planned. Subcontractors balance their own work to their convenience when the GC, or CM cannot show that the plan is already balanced.
Owners need to see these deliverables for each major design release:
- Resource-loaded schedules with continuous flow
- Explanations for any discontinuous work patterns
- Clear identification of bottleneck trades by General Contractor or CM
- Detailed explanation of why those bottlenecks cannot be accelerated
- Risk analysis of the schedule showing the risky areas and the probability of completing each major milestone
- Cash flow
LBMS during Construction
During construction, use the schedule as an early warning system.
- Track completed locations, to easily calculated the total quantity of work-in-place
- Report of total manpower on site daily to calculate actual productivity and actual production rates.
- Use those rates to forecast progress and to identify problems much earlier than in CPM systems.
Include the following items in the Owner’s Weekly and Monthly reports :
- Comparison of completed tasks and locations to plan
- Explanations for not implementing continuous work as planned
- Schedule forecast before control actions (when everything continues on the same production rate)
- Schedule forecast after control actions, and documentation of those control actions (for example, adding 5 carpenters to the drywall crew, working on Saturdays, 2-shift work for selected tasks, etc.)
- Problem tasks where production rate is < 80% of planned
- Percentage of production completed compared to the plan (for the whole project and each major construction phase, such as foundations)
- Resource forecast for the next month for each main subcontractor to reveal unrealistic resource assumption
- Updated cash flow forecast based on schedule forecast
Parallel LBMS and CPM
Trying to run parallel schedules in a project generally does not work well. CPM schedules traditionally work only as Owner reporting tools and have limited relevance in the field. The information content of a typical CPM schedule is extremely limited, lacking quantities and resources and show only tasks and durations without revealing the location, manpower and quantity assumptions behind the duration estimates.
Critical path and float are then faulty because they do not consider the requirement to have continuous, balanced flow of resources through the project. Only continuous workflow makes it possible to forecast production and give early warnings of problems.
Schedule optimization using location-based planning typically results in 10-15% compression – without either the need for additional resources, orfor increase in risk levels. This compression is achieved so that most of the tasks in the project have continuous flow. All optimization is theoretical unless the schedule is actually followed on-site and parallel schedules undermines this goal unless the schedules exactly match.
Location-based scheduling typically results in better quality, optimized, resource-based schedules in only 70% of the time required to build a CPM schedule.
To optimize a schedule from scratch takes about 50% of the time of converting a CPM schedule to LBMS and using that as the starting point of optimization. All of these facts speak to abandoning the practice of running parallel schedules.
CPM is included in LBMS, but only about 20% of LBMS information content is included in CPM (specifically logic layer 5: random CPM links).