07-Str-B2 · May 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format: National Exams, May 2016 — 07-Str-B2 Management of Construction. Three hours, closed book, one approved Casio or Sharp calculator permitted. Six questions of equal value (20 marks each); any five constitute a complete paper and only the first five answered are marked. All six are worked below so that the paper can be used for revision whichever five a candidate chooses.
Reference texts: Hegazy, T., Computer-Based Construction Project Management (Prentice Hall) — precedence networks with lags, total and free float, project overhead versus general overhead, and the bar-chart/S-curve control method behind Questions 1, 3 and 6; Hendrickson, C. & Au, T., Project Management for Construction (2nd ed., Carnegie Mellon) — Chapters 5 (cost estimation), 10 (scheduling) and 12 (cost control, monitoring and accounting), the source of the earned-value quantities used in Question 6; Halpin, D.W. & Senior, B.A., Construction Management (4th ed., Wiley) — competitive bidding, unbalanced bids, indirect-cost structure and construction safety; Sullivan, W.G., Wicks, E.M. & Koelling, C.P., Engineering Economy (17th ed., Pearson) — Chapters 5 and 6, present-worth analysis and the repeatability assumption for alternatives with unequal lives, used in Question 4; Peurifoy, R.L. & Oberlender, G.D., Estimating Construction Costs (6th ed., McGraw-Hill) — job overhead versus general overhead; Canadian Construction Documents Committee, CCDC 2 — Stipulated Price Contract (2020) and CCDC 23 — A Guide to Calling Bids and Awarding Contracts — bid-call practice, bid security and award criteria for Question 2; Ron Engineering (M.J.B. Enterprises line of cases) as summarised in Goldsmith, I. & Heintzman, T.G., Goldsmith on Canadian Building Contracts (5th ed., Thomson Reuters) — the Contract A/Contract B doctrine that governs a Canadian public bid call; WorkSafeBC, Occupational Health and Safety Regulation (Parts 4, 8, 11, 13, 18, 19 and 20) and the BC Workers Compensation Act, together with CSA Z259 (fall protection), CSA Z94.4 (respirators) and CSA W117.2 (welding safety) — the Canadian rule set behind Question 5.
Question 1 (network). Every activity letter and duration is printed inside its box and reads cleanly. The link routing was traced at high magnification: Start feeds A, D and G; a riser from the right edge of D feeds B; the horizontal link D → E carries the only labelled lag on the sheet, FS 6; a riser from the right edge of G feeds E; G also feeds H, H feeds I, A feeds B, B feeds C, E feeds F; and C, F and I terminate at End. Every unlabelled arrow is an ordinary finish-to-start link with zero lag, which is the only reading consistent with the drawing.
Question 6 (bar chart). Every percentage label falls on a week boundary, so the printed figures are cumulative percent complete at each week end. Planned: A 20/60/100 in weeks 1–3; B 10/80 in weeks 1–2, finishing in week 3; C 20/70 in weeks 3–4, finishing in week 5. Actual: A 10/50/90 in weeks 1–3, its bar closing in week 4; B 70 at week 2, its bar closing in week 3; C 50 at week 3, its bar closing exactly on the week-4 gridline. A bar that closes is read as 100 % complete from that week end onward, which is the standard convention and the only reading that lets part (c) be answered at all.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
Bid unbalancing is the deliberate redistribution of a contractor's money between the line items of a unit-price bid while the bid total is left unchanged or barely changed. Because a unit-price contract pays the contractor the tendered unit rate multiplied by the quantity actually measured in the field, the total the owner eventually pays depends on where the money sits in the schedule of prices, not merely on what the bid summed to on tender day. A contractor who understands that dependency can improve its own position substantially without ever submitting the lowest honest number.
Two distinct forms are practised, and an examiner expects both to be named. Front-end loading shifts money into the items that are executed first — mobilisation, site clearing, excavation, temporary works — and takes it out of items executed near the end, such as finishing, landscaping and commissioning. The bid total is unchanged, but the contractor is paid a disproportionate share of the contract price in the first progress payments. That converts the owner into an involuntary lender: the contractor finances its own operations with the owner's cash, improves the present worth of the contract to itself at the owner's expense, and, if it later defaults, walks away having already drawn more than the value of the work in place. Quantity-error or unbalanced-item bidding is the more aggressive form. The contractor studies the owner's estimated quantities, forms a judgement about which ones are wrong, and prices accordingly: a very high unit rate on an item it believes will overrun, and a correspondingly low rate on an item it believes will underrun. Provided the contractor's judgement about the field quantities is better than the designer's, the bid wins on the tendered total and then earns far more than that total once the true quantities are measured. Rock excavation, unsuitable-material disposal, dewatering and undercut items are the classic vehicles because their estimated quantities are the least reliable.
Detection is a quantitative exercise, and an owner who does it properly does it before award, not after. The primary tool is a comparison of each unit rate against the owner's own engineer's estimate and against the spread of the other bidders' rates for the same item. A bid schedule laid out side by side makes an outlier obvious: an item priced at three or four times the median of the field, or at a small fraction of it, is a flag. The second tool is a cash-flow test: the owner builds the payment curve implied by the bid against the tendered construction schedule and compares it with the curve implied by its own estimate. A front-end-loaded bid produces a visibly steeper early curve. The third is a re-run of the bid comparison using the owner's best current estimate of the true quantities rather than the tendered ones; a bid that is lowest on the tendered quantities but no longer lowest on realistic quantities has been unbalanced against a quantity error. Beyond the arithmetic, an owner should look for the tell-tale pattern of a mobilisation item priced far above any defensible cost of mobilising, and for rates that bear no relation to the resources the contractor's own schedule shows it deploying on that item.
The courses of action available depend on what the tender documents say, which is why the remedy has to be designed in before bids are called rather than improvised afterwards. A well-drafted instruction to bidders reserves the right to reject a materially unbalanced bid as non-compliant, and in Canada the Ron Engineering line of authority makes that reservation meaningful: submission of a compliant bid creates Contract A, and the owner's obligations under it — including its right to reject — are governed by the terms it published. Softer remedies are often preferable to outright rejection. The owner may cap or disallow the mobilisation item, typically by limiting it to a stated percentage of the contract price. It may require the bidder to justify the rate in writing and correct it if the justification fails. It may discount the front-end effect in the bid evaluation by comparing present worths of the payment streams rather than nominal totals. It may pay unbalanced items on a cost-plus or negotiated basis rather than at the tendered rate. And for the quantity-variation form, the standard structural answer is a variation-in-quantity clause providing that where the measured quantity of an item departs from the estimate by more than a stated threshold — fifteen or twenty-five per cent is usual — either party may require the unit rate for the excess to be renegotiated. That clause removes the prize the unbalancer is bidding for. Owners should also require bid security and a performance bond, so that the default risk created by front-end loading is transferred to a surety. Finally, the owner must apply whatever rule it publishes even-handedly to every bidder, because a rejection that cannot be justified against the published criteria invites a Contract A claim from the rejected bidder.
The second half of the question concerns award criteria for government work. The dominant criterion in Canadian public procurement is lowest compliant bid: the contract is awarded to the lowest-priced bidder whose tender satisfies every mandatory requirement of the call — correct form, bid security, acknowledged addenda, prequalification, bonding capacity, and any stated technical or safety qualification. Price decides among the bidders who clear those gates; it does not decide against bidders who do not. Increasingly, agencies supplement this with a two-envelope or weighted best-value model, in which a technical proposal is scored first and price is opened and combined with the technical score afterwards, and with prequalification, which moves the qualitative judgement to a stage before bids are called.
The advantages of the lowest-compliant-bid rule are real and explain its persistence. It is transparent and auditable: the winning number is public, the arithmetic is checkable, and a losing bidder can see exactly why it lost, which is essential where public money and political accountability are involved. It is objective, which drastically reduces the scope for favouritism, patronage or corruption. It is cheap and fast to administer for both owner and bidder. It maximises competitive pressure and therefore, on average, secures a low tendered price. And it is legally robust: because the criterion is mechanical, an award made under it is difficult to attack under Contract A.
The disadvantages are equally well known. The rule equates the lowest price with the lowest cost, which is only true if the specification is complete and the contractor is competent; where it is not, the owner buys the bidder who made the largest estimating error or took the most aggressive interpretation of the documents. That produces claims-oriented contracting: a contractor who has bought the job at a loss recovers through change orders, delay claims and disputes, and the owner's final cost exceeds the second-lowest bid. It ignores quality, schedule reliability, safety record and past performance unless those have been converted into pass/fail prequalification criteria, and it gives the owner no way to pay a modest premium for a demonstrably better builder. It penalises innovation, since every bidder is pricing the same prescriptive design and there is no mechanism to reward a better one. It exposes the owner to bid-error and abandonment risk, which is why bid bonds exist. And, most relevant to the first half of this question, it is precisely the criterion that rewards unbalancing: when only the tendered total is compared, a bidder who has moved money between items without changing the total is invisible to the award test. The practical Canadian answer is therefore a hybrid — rigorous prequalification, a lowest-compliant-bid award among the prequalified, and an instruction to bidders that reserves the right to reject a materially unbalanced tender.
