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.
The eight measures listed sit at different levels of the hierarchy of controls, and that is the organising idea an examiner is looking for. Elimination and engineering controls come first, administrative controls next, and personal protective equipment last, because PPE protects only the person wearing it and only if it is worn correctly. Several of the items below are engineering controls (guardrails, scaffolds, safety nets), several are administrative (ladder practice, welding procedure, first-aid provision), and only one is pure PPE. In British Columbia the governing instrument is the WorkSafeBC Occupational Health and Safety Regulation made under the Workers Compensation Act, and the prime contractor on a multiple-employer workplace carries the coordinating duty for all of them.
1. Fall protection — both, and it is the single most important measure on either type of project. Falls from height are the leading cause of construction fatality in Canada. WorkSafeBC Part 11 requires a fall-protection system wherever a worker may fall 3 m or more, or a lesser distance where the fall would involve unusual risk of injury, and requires a written fall-protection plan where a work area is 7.5 m or more above grade. The preferred solution is a guardrail, because it is a passive engineering control that requires nothing of the worker; only where guardrails are impracticable does one descend to a travel-restraint system, and only then to a personal fall-arrest system with a full-body harness, shock-absorbing lanyard and an anchor rated to 22 kN. On building projects the exposures are perimeter edges, floor and shaft openings, leading edges during deck placement, and roofing. On highway projects they are less obvious but real: bridge decks and falsework, retaining-wall and abutment work, deep excavation and trench edges, culvert and drainage structures, and work from the deck of a paver or on top of a tanker. Fall protection is therefore universal, but the system chosen differs: buildings favour guardrails and horizontal lifelines on repetitive floor plates, while bridge work relies more on engineered anchor points and travel restraint.
2. Scaffolding — predominantly building, with a real but narrower highway role. A scaffold is an engineering control that converts work at height into work from a guarded platform, and it is the standard access method wherever facade, masonry, cladding, glazing or interior finishing work must be reached repeatedly over a long duration. WorkSafeBC Part 13 requires scaffolds to be erected, altered and dismantled under the supervision of a qualified person, to be designed and rated to the load and safety-factor requirements of the applicable standard (CSA Z797), to be fully planked with toe boards and guardrails, to be tied to the structure at the prescribed intervals, and to be inspected before each shift. Building projects use scaffolding intensively, including swing-stage and mast-climbing systems on high-rise facades. Highway projects use it far less because the work is linear and mobile rather than static and vertical — but it appears wherever a highway project has a vertical structure: bridge pier and abutment forming, girder painting and rehabilitation, sign gantries, retaining walls and tunnel portals. Where the work moves along the alignment, an elevating work platform or under-bridge inspection unit usually displaces the scaffold because it can be repositioned in minutes.
3. Ladder safety — both, and the most under-managed item on the list. Ladders cause a disproportionate share of lost-time injuries precisely because they look trivial. The controls are largely administrative: use a ladder only for short-duration light work and not as a work platform where a scaffold or elevating platform is warranted; select the correct CSA grade for the duty and a non-conductive fibreglass ladder near any energised conductor; set a leaning ladder at about 75° to the horizontal (the familiar 4:1 pitch); extend it about 1 m above thelanding and secure it top and bottom; maintain three points of contact and never carry material up by hand; inspect before each use and remove damaged ladders from service. Both project types use ladders constantly — buildings for access between floors, shafts, hoardings and finishing trades; highways for access into excavations, manholes, formwork, pier caps and equipment. Note the interaction with item 1: a worker on a ladder above the fall-protection threshold who cannot maintain three points of contact needs a fall-arrest system as well as good ladder practice.
4. Personal protective equipment — both, mandatory, but always the last line of defence. The base kit is the same on either project: CSA Z94.1 head protection, CSA Z94.3 eye protection, CSA Z195 grade-1 protective footwear, and hearing protection selected to bring the exposure below the 85 dBA eight-hour limit. Beyond the base kit the two environments diverge sharply. Highway work is dominated by the traffic hazard, so high-visibility apparel to CSA Z96 class 2 or 3 is not merely good practice but the controlling item of PPE, worn with a traffic-control plan, and night work drives the choice toward class 3 with retroreflective banding. Building work generates far more overhead, cutting and chemical exposure, so face shields for grinding, cut-resistant gloves, chemical-resistant gloves for concrete and adhesives, and welding leathers dominate. The general principle applies on both: PPE controls no hazard at source, so it is added to engineering and administrative controls, never substituted for them.
5. Safety net — both, but genuinely useful only in specific configurations, and more common on highway structures than on buildings. A net is a passive fall-arrest control that catches a worker without requiring any action, which makes it valuable where a large area must be protected and personal fall-arrest anchorage is impractical — typically steel erection, bridge deck work over water or live traffic, and long-span roof erection. Good practice, and the net standards WorkSafeBC relies on, require a net to be installed as close as practicable beneath the work surface (its support structure certified by a professional engineer under OHSR Part 11), to extend far enough horizontally to catch a falling worker, to be drop-tested or certified, and to have sufficient clearance beneath so that a loaded net does not strike a lower level. Its most valuable secondary function on highway bridges is debris containment: a net or shrouded platform under a deck being rehabilitated protects the road or waterway below as much as it protects the worker. On building projects nets are less common in Canada than guardrails and personal fall arrest, because floor plates offer plentiful anchorage and guardrails are simply cheaper; they reappear on long-span steel and atrium work where neither is available.
6. Respiratory equipment — both, but for different contaminants. Respirators are PPE and therefore the last resort: WorkSafeBC Part 5 requires substitution, ventilation and enclosure to be considered first, and where a respirator is used it must be selected against the measured or estimated exposure, fit-tested, and supported by a written respiratory-protection programme with medical screening and clean-shaven-seal requirements under CSA Z94.4. On building projects the drivers are silica from cutting, grinding and drilling concrete and masonry; asbestos and lead in renovation and demolition, which trigger their own qualified-removal regimes; welding fume; isocyanates from spray foam and coatings; and mould in water-damaged renovation. On highway projects the drivers are respirable crystalline silica from milling, sawing and aggregate handling; asphalt fume and bitumen aerosols in paving; diesel particulate around plant; and, above all, oxygen-deficient or toxic atmospheres in confined spaces — manholes, culverts, wet wells, caissons and vaults — where a supplied-air respirator or SCBA, not a filtering facepiece, is the only acceptable device. That confined-space distinction is the single most important respiratory point on a civil project.
7. First aid — both, mandatory, with the level of service set by a written assessment. WorkSafeBC Part 3 requires every employer to conduct a first-aid assessment based on the number of workers per shift, the hazard rating of the work, and the surface travel time to hospital, and then to provide the attendants, supplies, equipment, transportation and a written procedure that the assessment calls for. Construction is a high-hazard classification, so the required level rises quickly with crew size. The distinguishing factor between the two project types is travel time, not hazard: a downtown building site is minutes from a hospital and can rely on a modest on-site capability plus emergency medical services, whereas a rural highway project may be an hour or more away, which drives a higher attendant level, a dedicated transportation vehicle, and a documented evacuation plan. Highway projects add two further complications: the site is linear, so coverage must be planned along its whole length rather than at one point, and the location of an injured worker must be communicable to responders by chainage or GPS. On both, records of every treatment must be kept, and the plan must be rehearsed rather than filed.
8. Welding safety — both, with the hazards essentially identical and the context different. Welding presents a compact bundle of hazards: fume and gases, arc radiation causing flash burn to the welder and to bystanders, hot work as an ignition source, electric shock, compressed-gas cylinder handling, and burns. The controls follow CSA W117.2 and WorkSafeBC Parts 12 and 5 — local exhaust ventilation at the arc as the primary fume control with respiratory protection only as a supplement, screens to shield adjacent workers from the arc, correct filter-lens shade for the process and current, flame-resistant clothing and leathers, flashback arrestors and proper cylinder securing and separation, and a hot-work permit with fire watch maintained during the work and for a period after it. Welders must be certified to CSA W47.1 for structural work. On building projects the elevated concern is fire in a structure containing combustible finishes, insulation and stored materials, which makes the hot-work permit and fire watch the governing controls, and confined-space welding in shafts and mechanical rooms raises the ventilation requirement. On highway projects the elevated concerns are welding at height on bridge steel, which combines the welding hazards with fall protection, and welding near live traffic, which adds arc-flash screening to protect drivers from the flash as well as the welder from the traffic.
| Measure | Control level | Highway | Building | Governing rule (BC) |
|---|---|---|---|---|
| 1 Fall protection | Engineering, then PPE | Yes — bridges, falsework, excavations | Yes — perimeters, openings, roofs | OHSR Part 11; CSA Z259 |
| 2 Scaffolding | Engineering | Limited — piers, abutments, portals | Yes — primary access method | OHSR Part 13 |
| 3 Ladder safety | Administrative | Yes | Yes | OHSR Part 13; CSA Z11 |
| 4 PPE | PPE | Yes — high-visibility governs | Yes — impact and chemical govern | OHSR Part 8; CSA Z96, Z94.1, Z94.3, Z195 |
| 5 Safety net | Engineering (passive arrest) | Yes — bridge decks, debris containment | Situational — long-span steel | OHSR Part 11 |
| 6 Respiratory equipment | PPE | Yes — silica, asphalt fume, confined space | Yes — silica, asbestos, lead, weld fume | OHSR Parts 5 and 9; CSA Z94.4 |
| 7 First aid | Emergency response | Yes — travel time and linear site govern | Yes | OHSR Part 3 |
| 8 Welding safety | Engineering + administrative | Yes — bridge steel, traffic exposure | Yes — hot work in combustible structure | OHSR Parts 12 and 5; CSA W117.2, W47.1 |
