07-Str-B2 · May 2017
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format: National Exams, May 2017 — 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 in the answer book are marked. All six are worked below so the paper can be used for revision whichever five a candidate chooses.
Reference texts: Hegazy, T., Computer-Based Construction Project Management (Prentice Hall) — activity-on-arrow networks, event-time calculations, time–cost trade-off and least-cost crashing, project cash flow and overdraft financing, and labour productivity; these chapters cover Questions 1, 3 and 5. Hendrickson, C. & Au, T., Project Management for Construction (2nd ed., Carnegie Mellon) — Chapter 10 (fundamental scheduling procedures), Chapter 11 (advanced scheduling techniques) and Chapter 12 (cost control, monitoring and accounting), including the S-curve and the financing of construction operations. Halpin, D.W. & Senior, B.A., Construction Management (4th ed., Wiley) — construction financing and the interest cost of a negative cash position, labour productivity and motivation, and construction safety management. Sullivan, W.G., Wicks, E.M. & Koelling, C.P., Engineering Economy (17th ed., Pearson) — Chapters 5 and 6, present-worth analysis and the repeatability (common multiple of lives) assumption for alternatives with unequal lives, used in Question 4. Peurifoy, R.L. & Schexnayder, C.J., Construction Planning, Equipment and Methods (9th ed., McGraw-Hill) — site layout and the physical determinants of crew output. AACE International, Recommended Practice 29R-03, Forensic Schedule Analysis, and the Society of Construction Law, Delay and Disruption Protocol (2nd ed., 2017) — the delay-analysis taxonomy required by Question 2. Canadian Construction Documents Committee, CCDC 2 — Stipulated Price Contract (2020), CCDC 40 — Rules for Mediation and Arbitration and CCDC 220/221/222 bond forms — the Canadian contractual machinery for notice, claims and dispute resolution. Transportation Association of Canada, Manual of Uniform Traffic Control Devices for Canada (MUTCDC), and the BC Ministry of Transportation and Infrastructure Traffic Management Manual for Work on Roadways, together with WorkSafeBC's Occupational Health and Safety Regulation (Part 18 Traffic Control, Part 4 lighting and workplace conditions, Part 8 personal protective clothing) — the Canadian rule set behind Question 6.
Question 1 (network). The node numbers, the activity letters and the i–j pairs printed in the data table agree completely with the drawn arrows: solid arrows run 1→2, 1→3, 1→4, 2→3, 2→6, 3→5, 3→6, 4→5 and 5→6, and one dashed arrow runs 2→5. The dashed arrow carries no letter in the table, so it is the network's dummy activity with zero duration and zero cost. Every arrowhead was checked individually at 8× magnification.
Question 5(b) (cash-flow chart). The values below are read from the printed chart. The smooth curve (cash out) reads 4.0, 11.5, 15.5, 45.0, 54.0, 71.5 and 71.5 thousand at the ends of months 1 to 7; the staircase (payment received) rises at the end of months 2 to 7 to 4.0, 12.5, 16.5, 47.5, 57.5 and 80.0 thousand. Both series are read to the nearest $500, which is the resolution the printed chart supports and is consistent with the word “estimate” in the question.
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.
A highway rehabilitation work zone is unusual among construction sites in that the principal hazard is not created by the work at all: it is the travelling public, moving at highway speed within a few metres of unprotected workers. Rehabilitation work compounds this because the road stays open, the work is linear and mobile, and the space available is whatever the lane closure leaves. Night work removes the one mitigating factor, daylight, in exchange for lower traffic volumes. In Canada the governing documents are the Transportation Association of Canada's Manual of Uniform Traffic Control Devices for Canada, the provincial supplement (in British Columbia, the Ministry of Transportation and Infrastructure Traffic Management Manual for Work on Roadways), and the occupational health and safety regulation of the province — in BC, WorkSafeBC's Occupational Health and Safety Regulation, Part 18 for traffic control and Part 4 for illumination and workplace conditions.
Plan the work zone before anyone goes near the road. Every closure should be covered by a written, signed and sealed traffic-management plan drawn from the standard layouts, showing the advance-warning area, the transition (taper), the buffer, the work area and the termination area, with taper lengths computed from the posted speed and the lane offset rather than guessed. The plan should be reviewed against the actual geometry — sight distance over crests and around curves, ramps and intersections inside the closure, and driveways — and it should be re-checked whenever the work moves. Traffic should be reduced to a single direction of exposure where possible, and lane closures should be timed against traffic counts so that the closure is not attempted while volumes are still high.
Separate workers from traffic physically, not merely visually. The hierarchy of controls applies here exactly as it does to any other hazard, and the elimination and engineering rungs are the ones that save lives. The strongest control is full closure with detour, which removes the hazard entirely and is often achievable at night when volumes are low. Next is positive protection: portable concrete barrier, water-filled barrier of a tested and accepted type, or a truck-mounted attenuator following mobile operations. Only after those should reliance be placed on channelising devices — cones, drums, delineators — which guide but do not restrain. The buffer space between the traffic and the first worker should be sized on stopping-sight distance for the posted speed and kept clear of workers, equipment and materials. Speed reduction through the zone should be enforced rather than merely posted, using police presence or automated enforcement where it is available, since compliance with an unenforced work-zone speed limit is generally poor.
Address the hazards that night specifically creates. The first is visibility of the worker: high-visibility apparel to CSA Z96 Class 3 with retroreflective striping is the minimum at night, and it should be checked for wear because retroreflectivity degrades with washing. The second is illumination of the work area. Lighting must be sufficient for the task — the regulation sets minimum illuminance levels by activity — but it must be aimed and shielded so that it does not glare oncoming drivers, which is the single most common defect on night jobs: balloon lights or shielded towers rather than bare floodlights aimed along the carriageway. Lighting must also be even, because a bright pool surrounded by darkness leaves a driver's eyes adapted to the wrong level and hides a worker who steps outside it. The third is conspicuity of the zone itself: retroreflective signs of the appropriate sheeting grade, more channelising devices at closer spacing than the daytime layout, sequential flashing arrow boards on the taper, and portable changeable-message signs placed far enough upstream that a driver can act on them. The fourth is driver impairment, which is statistically worse at night: fatigue, alcohol and drugs raise the probability of an intrusion, and the work zone must be designed on the assumption that a vehicle will eventually enter it. The fifth is worker fatigue and circadian disruption: shift lengths should be limited, rotation should be managed, rest facilities and hot drinks provided, and the schedule should avoid the low point in alertness in the early hours where the work permits. Cold, and the reduced dexterity that goes with it, is a related night hazard on shoulder-season work.
Manage the internal hazards of the work itself. Inside the zone, the dominant risk is the site's own equipment: rollers, pavers, milling machines, haul trucks and sweepers operating in a confined corridor with workers on foot. The controls are an internal traffic-control plan that separates equipment paths from worker paths and minimises reversing, spotters where reversing is unavoidable, reverse alarms and camera or proximity-detection systems, a rule that no worker walks behind a machine without positive acknowledgement from the operator, and blind-spot awareness training for both operators and workers. Beyond that lie the ordinary construction hazards intensified by the setting: asphalt fume and hot-mix burns, silica from milling and cutting, noise from milling and breaking, whole-body vibration, manual handling, excavation and utility strike where the work involves the subgrade, and fall exposure on structures. Each should be handled through the normal hierarchy — substitution or engineering control first, personal protective equipment last.
Build the management system around it. Technical controls are only as good as the organisation that maintains them. That means orientation and task-specific training for everyone who enters the zone, including subtrades and delivery drivers; certified traffic-control persons with proper equipment, positioned in escape-capable locations and rotated to hold attention; a nightly pre-shift briefing covering the layout in force that night and the changes since the last shift; documented inspection of the layout at the start of each shift and periodically through it, since cones get knocked over and signs get turned; a near-miss and intrusion reporting system, because intrusions are the leading indicator of a future fatality and are chronically under-reported; a written emergency response plan naming the access route for emergency vehicles into a closed carriageway, the muster point and the first-aid provision required by the regulation for the crew size and the response time; and clear stop-work authority vested in every worker, with visible management support when it is used. Finally, the plan should be reviewed after every change of configuration and after every incident, and the results fed back into the standard layouts, so that the organisation's work zones get safer with each job rather than repeating the same defects.
