Construction Schedule Delay Analysis: I Tested Every Task

Construction schedule delay analysis almost always starts from the same document: the float table. Which activities had slack, how much, and therefore who owes whom the days. It is the number that decides whether a delay was excusable, concurrent, or somebody’s fault, and it is on the front page of every claim I have ever read.

So I tested it. I took a 21-task renovation with three general crew, delayed every single task a day at a time, and re-solved the whole schedule after each one to see when the finish date actually moved. Twenty-one tasks, a few hundred solves. Three of them turned out to have nine days of float on paper and no tolerance at all.

Paired bar chart of twelve renovation tasks comparing total float with the delay each can actually absorb; roofing, driveway and landscaping each show nine days of float and zero days of tolerance.
Every task was delayed a day at a time and the whole plan re-solved. Grey is what the float table promised; blue is what survived contact with three crew.
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Resource Leveling Techniques, and Why Yours Guesses

Search for resource leveling techniques and you get lists: level within float, delay non-critical tasks, split tasks, reassign resources, adjust the calendar, fast track, add people. All real things you can do. None of them is what the button in your scheduling software is actually doing when you press it, and the gap between the list and the button is why two tools level the same plan and hand you two different schedules.

Underneath, there is one technique with two moving parts, and a lot of arbitrary choice in the second part. Here is what it did to a 21-task renovation.

Horizontal bar chart of the eleven tasks leveling pushed later, from Driveway and Landscaping at 14 working days down to six tasks at 3 days each.
Five of the eleven tasks that moved had no CPM float at all. A technique that only shifts slack tasks cannot produce this schedule.

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Resource Loading: The Chart Under the Gantt Chart

A resource loading chart is the histogram that sits under a Gantt chart: for each day of the plan, how many people that day needs. It is the least glamorous drawing in project management and the only one that ever told me anything I did not already know from looking at the bars.

Here is one for a 21-task house renovation, before and after the schedule was made to fit inside the crew that actually exists. The two panels hold exactly the same amount of work.

Two resource loading charts of the same renovation: before leveling the daily crew count peaks at 5 and exceeds the cap of 3 on 14 days; after leveling it never exceeds 3.
Same 155 crew-days under both panels. Leveling changes the shape of the histogram, not its area.
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Tradeline Payouts: Why Per Spot Is the Wrong Number

A broker emailed me a rate sheet once and I nearly moved a card over it. Their number was $275 a spot. The broker I was already with paid $250 for the same card. Twenty-five dollars is twenty-five dollars, so I started filling out the paperwork before I bothered to read the rest of the page — and then I saw the cycle length. That is the thing nobody puts in bold: tradeline payouts are quoted per authorized user spot, but the spot doesn’t last the same length of time at every broker. Once I divided by the months, the $275 offer was worth barely half of what I was already getting.

So this post is about the arithmetic I wish someone had handed me at the start. Not which broker is nicest to deal with — what a card actually earns, per month, and which of the things you can change about your card are worth money.

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Which Tradelines Should I Buy? Age Beats Limit

The question I get more than any other is some version of “which tradelines should I buy” — usually from someone staring at a broker’s list with forty cards on it, sorted by price, with no idea what separates the $500 one from the $1,400 one. The honest answer is that most of what you’re looking at is priced on one variable, and it isn’t the one people fixate on. Buyers walk in wanting the biggest credit limit they can afford. The listings are priced mostly on age.

I pull live pricing from three brokers every hour, so rather than tell you what I think, I’ll show you what the market is actually charging today and where the same card costs meaningfully different money depending on who’s selling it.

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