Chapter 29 — Exercises

Work these with a pencil and a calculator. Schedule arithmetic punishes mental shortcuts, and the only way to trust a number in a meeting is to have produced one like it by hand at least once.

Difficulty legend: ⭐ basic · ⭐⭐ applied · ⭐⭐⭐ advanced judgment · ⭐⭐⭐⭐ research and extension.

Selected numeric answers appear in Appendix J. Where a <details> block is given below, check yourself only after you have committed to an answer in writing.

Part A — Conceptual Understanding ⭐

A1. In one sentence each, define data date, remaining duration, and total float. Then state the one rule that connects all three.

A2. A schedule update has four inputs. Name them. Which one comes from a person rather than a document, and why does that make it the input most likely to be wrong?

A3. Explain the difference between retained logic and progress override in two sentences, without using the word "software." Then say what condition on a job makes the choice matter at all.

A4. Your project manager says: "The completion date hasn't moved in four updates — we're in good shape." Give three different situations that could produce that observation, only one of which is good news.

A5. Draw the two-by-two delay matrix from memory. Label both axes with the question each one answers, fill in all four cells, and say why one of the four is always empty.

A6. What is a fragnet, and why is modeling a delay as a single bar labeled "delay" worthless?

A7. State the cost-slope formula. Then state the two rules that govern crashing, and explain what goes wrong if you ignore either one.

A8. Distinguish recovery from acceleration in one sentence. Then name the single question whose answer determines which one you are doing.

A9. Why is float called a shared, consumable asset rather than a cushion? Answer using the Northgate steel chain — seven days, six spent by Kestrel, four spent by Caldwell — and explain how a pool of seven days absorbed ten.

A10. A schedule narrative has ten sections. Which one is most often omitted, and what specifically goes wrong four months later when it is?

Part B — Applied Analysis ⭐⭐

B1. The percentage that isn't an answer. Your drywall foreman reports the level-2 partitions are "about 80 percent done." The baseline duration was 25 work days and he has been at it for 22. Write the three questions you ask him next, in order, and say what each one is designed to detect.

B2. Reading a float trend. Two paths on your job:

Which path gets your attention this month, and why? Compute the month at which the second path reaches zero at its current rate. Then name the two documents you would go read before you talk to anybody.

B3. Consuming float is not delay. Your electrical subcontractor's overhead rough-in on levels 1 and 2 finishes 14 days later than the dates in the accepted update. That chain carried 21 days of total float at the start of the period. The sub sends a letter claiming 14 days of extended general conditions caused by your late ceiling-grid layout.

Answer four things: (a) how many days of project delay occurred; (b) what the sub is entitled to on a delay theory; (c) whether he might have a legitimate claim of a different kind, and what it would be called; (d) what you write down today, and why, even though you owe him nothing.

B4. Out of sequence. At a data date of contract day 210, activity P — level-3 overhead MEP rough-in has 26 CD remaining. Its finish-to-start successor Q — level-3 ceiling grid has 30 CD of duration, of which 9 days have been performed in the two zones where the rough-in is complete and inspected. Q has 21 CD remaining.

Compute Q's finish under retained logic and under progress override. State the difference in days and in dollars at a total daily exposure of $10,650. Then say which answer you would publish and what you would actually change about the schedule.

B5. The notice clock. On the 8th of the month, your owner's representative tells you verbally in an OAC meeting that the owner will not release the approved finish schedule until the board meets on the 29th. Your contract requires written notice of any event that may result in a claim for additional time within 10 days of the event.

State the date your clock started and why. Then explain why "we don't know the impact yet" is not a reason to wait, and write the two-sentence notice you would send.

B6. Reading a recovery schedule you were handed. A subcontractor submits a recovery schedule showing his remaining rough-in performed in 42 days instead of 61 by "increasing manpower." List the six things you check before you accept it, and identify which single one most often exposes a recovery schedule as fiction.

B7. The stable schedule. A schedule update arrives with 340 activities. Eleven activities show remaining duration but sit entirely to the left of the data date. Four activities show an actual start date after the data date. The projected completion is unchanged from last month. Write the three sentences you send back, and say what you are refusing to do until they are answered.

B8. Two instruments disagreeing. Your earned value report shows a schedule performance index of 1.04. Your CPM update shows the controlling path at −19 calendar days. Explain how both can be true at the same time, name the three ordinary mechanisms that produce it, and say which number you put in front of the owner and why.

Part C — Calculations and Deliverables ⭐⭐–⭐⭐⭐

C1. Run the update. ⭐⭐

Baseline network, durations in calendar days:

Activity A starts on contract day 0. Required substantial completion is contract day 300.

• (a) Run the forward and backward pass. State the project duration, the critical path, and the total float on activity E.
• (b) Now update at a data date of day 130. A finished on day 34. B finished on day 84. C is in progress with 18 CD remaining. Nothing else has started. Recalculate. What is the new projected completion, and by how many days did it move?
• (c) Compute total float on E and on the D–F chain at the new data date, measured against the required day 300.
• (d) At a total daily exposure of $9,400/CD, what is the exposure created by this update?

C2. The float absorption analysis. ⭐⭐

A curtain-wall procurement chain carries 12 calendar days of total float at the data date. Then: the fabricator's shop drawings are transmitted 5 days late by the general contractor; the architect takes 21 calendar days against a contractual 14; and the resulting release date misses the extrusion supplier's die-run window by 2 days, pushing the next run 28 days out. The fabricator recovers 9 days by ordering two profiles from stock.

Build the float absorption table. State the float after each event and the net impact on the completion date. Then answer: if the general contractor had transmitted on time, what would the impact have been?

C3. Crash it. ⭐⭐⭐

Network, durations in calendar days:

Crash data:

• (a) Compute the cost slope for each activity.
• (b) Find the project duration and the critical path.
• (c) Crash the project to the shortest duration that is worth buying, given a daily exposure of $8,900/CD. Show every step, recalculate after each one, and state where the critical path moves.
• (d) State your stopping rule and the marginal cost of the first day you declined to buy.

C4. Price the four levers. ⭐⭐

A 10-person crew, burdened straight time $61.00/MH, overtime hours at $85.00/MH. You need about 25 percent more output for six weeks.

• (a) Compute the weekly cost of a 40-hour week and of a 6 × 10 = 60-hour week.
• (b) At an assumed sustained-overtime efficiency of 0.85, compute the effective productive man-hours per week and the cost per productive man-hour under each schedule.
• (c) Separate the extra weekly cost into the straight-time-and-burden component and the overtime premium component. Then compute the value of the fatigue loss and compare it to the premium.
• (d) Price the alternative: a second crew of 4 at straight time, with an assumed 8 percent congestion loss on the combined crew. Which option delivers 25 percent more output for less money, and what non-financial factor would make you choose the other one anyway?

C5. Sort the delay and write the notice. ⭐⭐⭐

A 27-calendar-day slip in the projected completion of a $14,000,000 municipal project. Liquidated damages $1,800/CD; your actual extended general conditions burn $2,050/CD; your bid carried extended general conditions at $1,750/CD. Causes, all established from contemporaneous updates:

• (a) Classify each block using the two-by-two matrix.
• (b) State the total time extension you request and how many of those days are compensable.
• (c) Compute your recoverable extended general conditions and the liquidated damages you avoid.
• (d) Compute what the 8 concurrent days cost you compared with what they would have been worth if they had been purely owner-caused.
• (e) Write the first two sentences of the notice.

C6. Reconstruct the missing updates. ⭐⭐⭐

Using the Rivermont Elementary reconstruction in Case Study 29-2: the gym chain float readings were +11, +2, −9, −19, −28, −34 at the ends of months 4 through 9. Recovery cost at each point was approximately $0, $14,000, $41,000, $96,000, $210,000, and unavailable.

• (a) Plot cost of recovery against days of float lost. Describe the shape of the curve in one sentence.
• (b) Compute the cost of recovery per day recovered at each of the four points where recovery was available. What happens to that ratio, and why?
• (c) At a total daily exposure of $5,142.62, compute the point at which recovery stops being financially rational if you ignore the school-opening date. Then explain in two sentences why that answer is wrong on this particular project.

C7. Build the decision page. ⭐⭐⭐

You have a 19-calendar-day slip on a job with liquidated damages of $3,000/CD and extended general conditions of $2,600/CD. Three acceleration packages are available: 6 days for $54,000; 12 days for $134,000; 16 days for $221,000 (each figure includes enabling costs).

• (a) Build the four-row decision table — do nothing plus the three packages — with total cost and forecast completion.
• (b) Identify the financially optimal option and state the spread between the best and worst acceleration options as a percentage of the $14,000,000 contract.
• (c) Add the two columns that are not denominated in dollars: peak trades stacked and rework exposure. Invent nothing — state what you would have to go find out in order to fill them in.
• (d) Write the recommendation sentence. It may not contain a dollar sign.

Part D — Judgment and Ethics ⭐⭐⭐

D1. Your project executive asks you to lengthen six unstarted activity durations "so we have some room in the schedule." Each change is individually defensible; you could write a sentence justifying any one of them. Together they create 11 days of float on the path where the owner's late equipment decision is about to land. Is this manufacturing float or prudent scheduling? Write the test you would apply, and then apply it.

D2. An owner demands a recovery schedule within seven days for a 20-day slip you believe is roughly half theirs. You have not yet completed your analysis. Draft your transmittal: cooperate fully, give away nothing, and do not sound like a lawyer. Then say what would change in your draft if the contract required you to submit a recovery schedule "at no additional cost to the Owner."

D3. Your superintendent tells you privately that the recovery schedule you are about to submit — which shows the drywall crew doubling — is not achievable, because the subcontractor does not have the people and will not hire them. Your project executive has already promised the owner the recovery. What do you do, in what order, and what specifically do you refuse to do? Name the cost of each choice to you personally and be honest about it.

D4. A delay consultant retained by your company suggests that if you re-sequence four relationships in the current update — all defensible on their own — the owner's late finish-schedule release lands on the critical path and your extension request becomes much stronger. Nothing he proposes is false. Where exactly is the line, and how would you describe it to a young project engineer who genuinely cannot see the difference between this and ordinary scheduling judgment?

D5. You are two months into an acceleration. Near-miss reports on the accelerated elevations are running at roughly triple the job's baseline rate. No injury has occurred. Recovering the remaining five days requires four more weeks of six-day weeks. The owner has a hard occupancy date behind it. Write what you say to your project executive, what you say to the owner, and what you say to the superintendent — and note where those three statements differ and whether that difference is defensible.

Part M — Mixed and Interleaved Practice ⭐⭐–⭐⭐⭐

M1. With Chapter 14 and Chapter 16. Take the Northgate procurement chain — anchor-bolt submittal, engineer review, mill release, fabrication, delivery. Identify every point in that chain that is a discrete external constraint rather than a continuous activity. For each, state what you would have had to ask, of whom, at buyout, in order to know the constraint existed. Then write the four questions you will ask every long-lead subcontractor on your next job.

M2. With Chapter 28. Your month-6 cost report shows self-perform framing running at a productivity factor of 0.87 and forecast $46,000 over. Your month-6 schedule update shows the framing chain with 12 days of float, unchanged from last month. Explain precisely how both can be true, what each instrument is measuring, and what you would do about it — in that order.

M3. With Chapter 30. A job reports SPI 0.97 and a critical path at −16 calendar days. A second job reports SPI 0.88 and a critical path at 0. Which one is in more trouble, and what is each instrument telling you that the other cannot? Then state the one sentence you would add to every earned value report you ever issue.

M4. With Chapter 27. Your six-week look-ahead shows 14 activities scheduled to start in the next two weeks, of which 6 have open constraints. Your monthly schedule update shows all 14 starting on time. Reconcile the two documents. Which one is lying, and what does the other one need in order to stop?

M5. With Chapter 24 and Chapter 20. Build the causal chain from a schedule decision made in a trailer to a lifted scaffold plank in week 34. There should be at least six links. For each link, name one control that would break the chain and state who owns it. Then say which of your six controls is the cheapest and which is the one most likely to be skipped.

M6. With Chapter 5 and Chapter 31. Your contract has one notice period for change-order pricing and a different one for delay claims. Explain why a single event can trigger both clocks, why satisfying one does not satisfy the other, and design the one-page log you would keep to make sure neither is missed. Note where the answer depends on jurisdiction and where it depends on the contract form.

Part E — Research and Extension ⭐⭐⭐⭐

E1. Find a real scheduling specification. Public agencies frequently publish their standard specifications online — state departments of transportation, large school districts, university systems, and federal construction agencies. Find one and read its scheduling section end to end. Then answer, in writing: what is the required update frequency and data date? What must the narrative contain? Does it prescribe a delay-analysis method for extension requests? Does it say who owns float? And what is the consequence of a non-compliant submission — is it a withholding, a non-payment, or nothing at all? Compare what you find with the summary in §29.1 and note every place your specification is more demanding than this book led you to expect.

E2. Read the frameworks by name. Locate the current recommended practice on forensic schedule analysis published by AACE International, and the Society of Construction Law Delay and Disruption Protocol. You do not need to read either cover to cover. Read enough to answer three questions: how does each one classify the methods of delay analysis; what does each say about concurrency; and what does each say about who owns float? Then write one page on where the two frameworks agree, where they differ, and what a contractor should do when the owner's consultant is working from one and yours is working from the other. Note explicitly that neither document is law and that both describe practice which varies by jurisdiction.

E3. Interview a scheduler. Find someone who runs monthly updates on a real project — a project controls manager, a scheduling consultant, or a superintendent who does it themselves on a small job. Ask three questions: Where do your remaining durations actually come from? What is the most common thing you have to argue with a project manager about? When was the last time an update told you something nobody in the field already knew? Write up what you learn in one page and compare it to §29.3. If their answer to the third question is "never," that is a finding — analyze what it means about how that job is being run and whether it is a criticism or a compliment.