Getting the Most Bang for the Buck in Construction Project Schedule Compression

Delivering a balanced baseline schedule (zero-days total-float (TF)) is a fundamental construction scheduling contract requirement, as is adhering to it for the duration of the project timeline. Relationships between activities are established, as the scheduler carefully tailors duration and lags to fit the contract requirements. Too often projects come prepackaged with overly aggressive deadlines, and the schedule becomes an exercise in mitigation before the baseline begins to develop.

Savvy contractors recognize straight-away projects that come with such aggressive deadlines. Their schedulers cannot run out the timeline without having in mind some sort of “pre-compression strategy,” or a general idea of the longest-path, and how to foreshorten it. This attribute can be evidenced in the free- and total-float tallies, which will give one an idea of how tightly sequences are strung together.

The showing of high float values in the schedule is universally frowned upon by builders, because they worry the owner might notice it, and begin to compete for it. Owners do this essentially because “time is money.” However; unless the contract stipulates otherwise free-float belongs to the collective project: not to any one party. That being said, owners always seem to be circling the wagon when free-float is more than fifteen or twenty-days. They may even include contract requirements intended to limit what they perceive as float manipulation, or devices schedulers use to artificially show low free-float – micromanagement, all of which can make it difficult for a scheduler to do his job.

Unfortunately, not all owners have a comprehensive understanding of the nuances of free-float, as opposed to total-float: only a reduction in the total-float can yield an earlier finish-date. Yet, they frequently salivate at high free-float values for insignificant activities on shorter, non-driving float-paths. For example, start-to-start + lag (SS+) compression for trades in the critical-path – such as carpentry and MEP work, is typical, and will net positive float, whereas secondary trades on longer float-paths – toilet accessories, landscaping, and painting can generally fit catch-as-catch-can. Thus, a contractor may sometimes rush non-driving work at the owner’s behest, only to realize that the effort had no effect on the end-date. Read: compressing float of non-driving activities is generally a poor ROI, as it increases resource needs without any salient positive benefit.

Before a scheduler implements his pre-compression strategy in a baseline, best practice dictates that he should first develop an optimized schedule according to an average project delivery timeline, before he begins peeling float away. In this way, he knows exactly how long the project ought to run-out on a good day, and how much compression is necessary to bring it in accordance with a sooner desired end-date. The exercise will help the contractor in determining compression rates, and the extra expenses needed to facilitate the compressed baseline, as well as future recovery schedules; costs he will seek to pass on to the owner.

For his pre-compression effort a scheduler may shorten activity durations by either adding resources or decreasing lags. Naturally, any sort of deviation from a customary project delivery must be vetted with the respective players or contractors, and then approved by the owner. Some may go along willingly, whereas others may not be able to comply, or might require an upcharge to cover additional expenses, such as shift-work, enhanced general conditions, and contingencies for typical rush-job mishaps:

• Trade congestion
• Access issues
• Productivity rate drop-off
• Increased likelihood of mistakes and tear-out work
• Increased likelihood of accident or injury

Given all the downsides of compression, it is no wonder contractors are loath to speed up their works. If the contractor is the cause of a delay, he likely will absorb the costs of the uptick, whereas he will seek to charge the owner for recovery measures, in the event of disruption.

Schedule compression should be a scientific undertaking, not an exercise in arbitrary siege-and-triage. We’ve all seen that, and it’s not pretty. In any case, it should be a seasoned scheduler who is in the best position to report on the impact of proposed mitigation or recovery efforts. Field experience will trump desk-duty, here, when it comes time to think through recovery efforts in real-time. With this in mind, the project will get the most bang for the buck when crunch-time comes.