CONSTRUCTION EDITED Flashcards
An excavator has a bucket capacity of 2.8 yd3.
Its operation cycle consists of the following phases:
(a) excavation time = 45 sec,
(b) travel time (two-way) = 4 min, and
(c) dumping/transfer time = 30 sec.
Assume an overall efficiency factor for the excavator = 85%. The quantity of material to be excavated (bank measure) = 50,000 ft3.
The material has the following properties:
Swell = 20%
In situ unit weight = 120 lb/ft3
Water content = 30%
Assuming 8-hr workdays, the number of days required to complete the job is most nearly:
A. 9
B. 10
C. 11
D. 13
11
- An excavator has a bucket capacity of 3.0 yd3.
Its operation cycle consists of the following phases:
(a) excavation time = 45 sec,
(b) travel time (two-way) = 4 min, and
(c) transfer time (to trucks) = 45 sec.
The excavator transfers the excavated material to a fleet of trucks that carry the material offsite.
The following data is given:
Overall efficiency factor for the excavator = 90%
Truck capacity = 15 yd3
Truck cycle time (transfer + two-way travel + dumping) = 90 min
The quantity of excavated material = 2,600 yd3 (loose)
The number of trucks needed to balance the production of the excavator, assuming 8-hr workdays, is most nearly:
A. 2
B. 3
C. 4
D. 5
3
- The architect for a warehouse building has proposed a design change to ensure compatibility with local building codes. The revised SOW is to substitute one layer of 5/8-in.-thick sheet rock with two layers of ½-in.-thick fire code (FC) GWB and to provide insulation within the wall cavity.
The building plan dimensions are: 180 ft × 200 ft
Floor-to-ceiling height: 12 ft
Openings: eight 6 ft 0 in. wide × 10 ft 0 in. high openings
Labor rates
Carpenter foreman (working) $50.00 fully burdened
Carpenter (journeyman) $40.00 fully burdened
Laborer $25.00 fully burdened
Work crew
4 carpenters
2 laborers
1 working foreman
Work crew productivity (based on 8 hr/day)
GWB installation 960 ft2/L.H.
Insulation 1,920 ft2/L.H.
Material costs (add 10% waste factor for all materials)
4 ft 0 in. × 10 ft 0 in. × ½ in. GWB (FC) $0.285/ft2
4 ft 0 in. × 10 ft 0 in. × 5/8 in. GWB $0.255/ft2
Insulation $0.45/ft2
Contractor’s overhead 10%
Contractor’s profit 5%
The complete cost ($) of the change order for the
revised SOW is most nearly:
A. 3,300
B. 4,200
C. 9,800 D. 7,800
9,800
- A 450-ft-long canal (trapezoidal section: 19-ft-
bottom width, 3H:2V side slopes) is to be lined with
concrete to a nominal thickness of 8 in. Material
waste is estimated to be 5%.
Concrete cost = $98/yd3
Concrete pour rate = 8 yd3/hr
Surface finishing compound is purchased in 5-gal containers costing $40 each
Coverage of surfacing compound = 300 ft2/gal
The total material cost ($) is most nearly:
A. 75,000
B. 85,000
C. 95,000
D. 105,000
105,000
- Dump trucks with a capacity of 16 yd3 are used to dispose of excavated materials from a site. The distance from the dump-site is 4 mi and the average speed of the dump trucks is 30 mph. The bucket capacity of the power shovel is 3 yd3; power shovel excavation rate is 10 yd3/min (bank measure); the transfer time to the dump trucks
(per 3-yd3 load) is 40 sec; and a dump time (per 3-yd3 load) is 30 sec. The excavated material has a swell of 10%.
The factors affecting the job site productivity of the dump truck are: 0.80 for equipment idle time and 0.70 for operator efficiency. If a fleet of dump trucks is used to haul the excavated material, the number of trucks needed is most nearly:
A. 3
B. 4
C. 5
D. 6
5
- A certain project includes the activities summarized in the table below. The start date of the project is week 0. The project duration (weeks) is most nearly:
A. 32
B. 36
C. 41
D. 44
41
- A 6-in.-square unreinforced-concrete beam is loaded in third-point loading on a simple span of 5 ft. The test is conducted at 28 days after the concrete beam is cast. If the failure occurs by flexural cracking within the middle third of the beam when load P = 800 lb, the 28-day
compressive strength (lb/in.2) of the concrete is most nearly:
A. 6,500
B. 5,500
C. 4,500
D. 3,500
3,500
- A 6-in.-diameter × 12-in.-height concrete cylinder fails at a transverse load of 55,000 lb at 28 days in a split cylinder test. The 28-day compression strength (lb/in.2) of the concrete is most nearly:
A. 6,200
B. 5,200
C. 4,200
D. 3,200
5,200
- Normal weight concrete (unit weight = 145 lb/ft3) is placed at a rate of 12 ft/hr into 18-ft-high column forms. The blended cement mix contains 30% fly ash but no retarders. Average concrete temperature during curing is 50°F. The maximum lateral design pressure (lb/ft2) for the design of forms is most nearly:
A. 2,600
B. 2,760
C. 2,150
D. 2,300
2,600
- A temporary road closure (not exceeding 20 min during the daytime) is established around a 1,250-ft long work zone (including a buffer space) on a freeway. The distance (ft) from the centerline of the work zone to the location of the ROAD WORK AHEAD sign is most nearly:
A. 4,800
B. 5,800
C. 6,800
D. 7,800
5,800
- Whenever a masonry wall is constructed, a limited access zone is to be established. Which of the following is true?
A. The limited access zone shall run to the same length on both sides of the wall.
B. The width of the limited access zone shall be wall height plus 2 ft.
C. The width of the limited access zone shall be wall height plus 4 ft.
D. If provided along the entire length of the wall, the width of the limited access zone is based on the judgment of the contractor.
The width of the limited access zone shall be wall height plus 4 ft.
- According to OSHA, lifelines shall be secured above the point of operation to an anchorage or structural member capable of supporting a dead weight (lb) of at least:
A. 5,000
B. 4,500
C. 4,000
D. 3,200
5,000
- According to OSHA, the limiting exposure (dB) to impulse or impact peak noise level is most nearly:
A. 80
B. 100
C. 120
D. 140
140
- A job requires specially engineered fill to be hauled from storage to the job site and then placed and compacted. Given the following information the installed cost ($/yd3) of the fill is most nearly:
Compacted volume required at job site 15,000 yd3
Distance from storage to job site 32 mi
Average truck speed 32 mph
Truck capacity (net) 50,000 lb
Truck load time 25 min
Truck unload time 10 min
Truck operating cost $80 per hr
Cost of fill at storage facility $3 per ton
Compacted unit weight of fill 140 lb/ft3
Cost to place & compact fill $0.50 per yd3
A. 15
B. 27
C. 23
D. 22
22
- The following table shows areas of cut and fill sections at locations 50 ft apart. Assume shrinkage = 12% and bulking = 25%. Cumulative
earthwork (yd3) between stations 0 + 0.00 and 3 + 0.00 is most nearly:
A. 1,340
B. 1,850
C. 2,200
D. 2,500
1,340
- A contractor has the following options for a project lasting 18 months:
Option A:
Monthly rental of excavation equipment at $15,000 per month + operating costs $2,000/month
Option B:
Purchase equipment for $200,000
Maintenance costs = $8,000/month
Resale value of equipment after 18 months = $120,000
Nominal interest rate = 10% p.a.
The benefit-cost ratio of option B (purchasing) is most nearly:
A. 0.95
B. 1.25
C. 1.55
D. 1.95
1.55
- An excavation plan is outlined in the following figure. Each grid square is 50 ft. × 50 ft. The numbers are depth of cut (ft.) at indicated
locations. The total volume of cut (yd3) is most nearly:
A. 4,500
B. 5,000
C. 5,500
D. 6,000
4,500
- An existing landfill, in the shape of a truncated pyramid, is rectangular at the base with plan dimensions 4,000 ft. × 2,500 ft. The free-standing sides slope 3H:1V. The height of the landfill is 12 ft. The top of the landfill must be covered with cover soil to a depth of 18 in. The amount of cover soil (yd3) required is most nearly:
A. 525,000
B. 650,500
C. 712,200
D. 821,435
525,000
- The following table shows ordinates of a mass haul diagram for a highway construction project. The free haul distance is 300 ft. Overhaul cost is $3.70/station-yd. The total cost of overhaul is most nearly:
A. $35,000
B. $40,000
C. $45,000
D. $50,000
$40,000
- The total duration of a project was estimated as follows:
522 working days at 6 days per week and 10 hr a day of work.
30 days (10 hr per day) for contingencies such as bad weather, which would be worked on weekends and holidays.
The labor agreement defines the regular work day as an 8-hr-long week-day. Labor cost for premium time is 50% for hours during the week, and 80% for weekend work. What is most nearly the overall
labor premium rate for the project?
A. 1.25
B. 1.28
C. 1.31
D. 1.34
1.25
- A roller is used to compact soil to a specific density. The roller can achieve this target density for a 6-in. layer of material in four passes. The following specifications are given:
Width of roller drum = 8.0 ft
Forward speed of roller = 3 mph
Overall efficiency of roller = 80%
Soil shrinkage = 15%
The material delivery rate (bank measure) to the site is 950 yd3/hr. The number of rollers required to keep up with this material delivery rate is most nearly:
A. 1
B. 2
C. 3
D. 4
2
- A 14-ft-high wall is placed at a rate of 4 ft./hr. Concrete is lightweight (135 pcf) made with Type I cement and a retarding admixture. The average concrete temperature is 60°F. The lateral design pressure exerted by the fresh concrete is most nearly:
A. 870
B. 750
C. 900
D. 725
870
- Specifications for a construction job state that wall forms can be removed once the concrete reaches a compressive strength of 3,400 psi. The maturity curve (Nurse-Saul) for the concrete is shown in the figure below. The cement hydration is assumed to cease below a temperature of 30°F. The average temperature of the concrete during the curing process is 70°F. The number of hours that the contractor has to wait before removing forms is most nearly:
A. 24
B. 36
C. 48
D. 60
48
- An activity on an arrow network for a project is shown below. Numbers adjacent to arrows are activity durations (weeks). The total float (weeks) for activity G is:
A. 0
B. 1
C. 2
D. 3
1
- As part of the PERT analysis of a project, durations are estimated for activities A through G and summarized in the table below. The critical
path for the project is ACEF.
22
- A new earth haul project requires moving 323,000 ft3 (bank measure) of excavated material to a location 12 mi away. A bidding contractor had completed a similar project (size and scope) 2½
years ago. The proposed price for the job on record was $525.00 per dump-truck load. Annual construction inflation factor is 3.2%. The
contractor uses a fleet of dump trucks with 26-yd3 capacity (heaped). The excavated material has a swell factor of 25%. The contractor’s bid ($) should be most nearly:
A. 262,000
B. 302,000
C. 326,000
D. 353,000
326,000
- A building construction site is represented by the following rectangle ABCD. The original elevation of the water table at the site is 325.8 ft (above sea level). The dashed line shows the limits of proposed construction. The bottom elevation of the mat foundation for the building is 325.65 ft. Steady state pumping from a 9-in.- diameter well at point B is to be used to lower the GWT. The transmissivity of the underlying aquifer is 250 ft2/hr. During construction, the GWT must
be lowered to at least 5 ft. below the bottom of the foundation and no higher than an elevation of 324.0 ft. within the limits of the site. The minimum steady-state pumping rate (gal/min) required is most nearly:
A. 1,000
B. 1,500
C. 2,000
D. 3,000
3,000
- A contract has 90 days remaining until completion. Early completion will be paid $18,000 bonus per day that the duration is shortened.
Activities on the critical path are targeted for “crashing.” Critical activities can be accelerated by allocating additional crew units. Additional cost and schedule reduction are shown in the table
below. If crews must be added as a complete unit, the net bonus is maximized by the addition of how many crews?
A. 1 additional crew unit
B. 2 additional crew units
C. 3 additional crew units
D. None of the crashing schemes are profitable
1 additional crew unit
- The activity on a node diagram for a project is shown below. All durations are in weeks. All relationships are finish to start unless noted otherwise. The free float (weeks) of activity A is:
A. 0
B. 1
C. 2
D. 3
0
- All costs for a construction project are classified as either direct costs (material, labor, etc.) or indirect costs (leasing and rental costs,
utilities, etc.). The estimated variation of these cost categories vs. project duration (weeks) is shown. The optimum project duration (weeks) is most nearly:
A. 10
B. 13
C. 16
D. 19
16
- A 5-story structure steel frame is to be constructed. Story height is 12 ft. The maximum tolerance for out-of-plumbness of the columns (in.) at the fourth floor is most nearly:
A. 0.25
B. 0.65
C. 0.95
D.1.15
1.15
