MT381 Unit 7 Resource-Leveled Construction Schedule Example

Ten Electricians and Two Telehandlers: An MT381 Unit 7 Resource-Leveled Schedule and the Float It Spends

[Student Name]

Purdue University Global

MT381: Construction Planning and Scheduling

Unit 7 Resource-Leveled Schedule

[Instructor Name]

[Date]

The crews, limits and results are composite; the leveling was computed with the stated script, and the sources cited are real.

The Two Resources

Electricians are assigned by activity: six for overhead rough-in and six for in-wall rough-in on each level, two for trim-out on each level and four for setting and terminating the switchgear. The electrical subcontractor has committed ten electricians to the job. Telehandlers are limited to two by the staging area on the north side of the site; framing, curtain wall and roofing each need one, and brick veneer needs two for its scaffold and pallets.

The Early-Date Histogram

Plotted from early dates, electrician demand overlaps in two places. From July 15 to July 28, level 1 in-wall rough-in runs alongside level 2 overhead rough-in; from July 29 to August 11, level 2 in-wall rough-in runs alongside level 3 overhead rough-in. Each overlap puts twelve electricians on the job, two more than committed, on twenty working days in all. Telehandler demand peaks at four, from July 19 through the rest of July, when framing, roofing and brick all run together, and exceeds two on 31 working days through September 3.

Why the Peak Matters to the Subcontractor

A peak of twelve for four weeks is not just a number above a line. To meet it, the electrical subcontractor would have to pull two electricians from another job, hire them for a month or work the existing crew overtime, and each choice has a cost. Mubarak (2015) points out that a crew that swells and shrinks repeatedly costs more than a steady one, through hiring, orientation and lost learning, which is why contractors prefer histograms that rise and fall gradually even when the total hours are the same. The commitment of ten reflects what the subcontractor can staff without disrupting its other work.

The Leveling Script

The script uses a serial method. It considers activities in order of their late start, so the activities with the least room to move are placed first, and it schedules each one at the earliest date its logic allows on which its crew fits under the limit for every day of its duration. Hegazy (1999) describes leveling as a trade-off between resource limits and project duration that heuristic and optimization methods approach differently; the serial late-start rule is a common heuristic and is transparent enough to check by hand.

Three Runs

Run one, unlimited, reproduces the early dates and the December 15 finish.

Run two caps electricians at ten. Rough-in on each level must take turns. The four-activity level 2 rough-in chain, from overhead work to the cover inspection, slides ten working days, starting July 29 instead of July 15. The level 3 rough-in chain slides twenty, starting August 26 instead of July 29. The histogram never rises above ten. Completion holds on December 15, because both chains had enough float: the level 2 chain keeps 19 of its 29 days and the level 3 chain keeps 11 of its 31.

Run three caps electricians at ten but allows twelve from July 20 through August 24. The rough-in chains on levels 2 and 3 slide only three days, waiting for the window to open, and then run as planned. Two additional electricians are needed on 17 working days, from July 20 to August 16. The level 2 chain keeps 26 days of float and the level 3 chain keeps 28. Completion again holds on December 15.

Every run finishes on December 15; what differs is how much margin the job keeps for the problems it has not met yet.

Telehandlers in the Same Pass

Telehandlers are leveled in the same pass with a limit of two. Framing and roofing keep their dates because they are ahead in priority, and brick veneer, which needs both machines, slides 36 standard working days later, starting September 8 instead of July 19 and finishing October 28. Brick had 48 days of total float, so 12 remain. Paving and landscaping, which follow the brick, slide with it, leaving paving 11 days and landscaping 13. Completion is unaffected.

What Leveling Spent

Float consumed by leveling is listed activity by activity, because it is no longer available to absorb a late delivery or a bad week of weather. In run two, the level 3 rough-in chain falls from 31 days to 11, and the level 2 chain from 29 to 19. In both runs, brick falls from 48 to 12, paving from 49 to 11 and landscaping from 50 to 13. Those three exterior activities now sit within a few weeks of the critical path in late fall, when the weather calendar removes three days a month.

Checking the Leveled Schedules

Each leveled run was checked in three ways before its results were used. Every relationship in the network still holds: no activity starts before its predecessors allow, and every lag is respected. The resource limit holds on every day, which the leveled histograms confirm. And no activity was split, since the script schedules each activity as one continuous block; splitting rough-in into pieces might reduce the slide further, but it would also add mobilizations the subcontractor would charge for.

Options Not Tested

Two other ways to meet the peak were considered but not run. Overtime for the existing ten electricians could cover part of the gap, but sustained overtime reduces productivity, and four weeks of it would likely lengthen rough-in rather than shorten it. Resequencing rough-in so that levels 2 and 3 run together, with level 1 later, would change crew-flow logic that the network marks as preferential, and is left for discussion with the subcontractor.

Recommendation

Adopt run three. Two extra electricians for 17 working days cost far less than losing twenty days of margin on the level 3 rough-in chain, which also carries the cover inspection that drywall on level 3 waits for. Ask the electrical subcontractor in writing to confirm twelve electricians for the window by June 15. For telehandlers, accept the brick slide but schedule a monthly review of brick and paving float through November, since their remaining margin is now small. Hinze (2012) notes that a leveled schedule is only as good as the resource commitments behind it, so the commitment, not the histogram, is the real deliverable.

Each Run's Critical Path

The critical path does not change in any run: steel through curtain wall, then interiors and closeout. In run two, however, the level 3 rough-in chain becomes near-critical, within eleven days, and is flagged on the reduced network for the update in Unit 8.

References

Hegazy, T. (1999). Optimization of resource allocation and leveling using genetic algorithms. Journal of Construction Engineering and Management, 125(3), 167-175. https://doi.org/10.1061/(ASCE)0733-9364(1999)125:3(167)

Hinze, J. W. (2012). Construction planning and scheduling (4th ed.). Pearson.

Mubarak, S. (2015). Construction project scheduling and control (3rd ed.). Wiley.