PE Civil (NCEES Principles and Practice of Engineering) — All Questions

A task has an earned value (EV) of $8,000 and an actual cost (AC) of $10,000. What is the Cost Performance Index (CPI)?

• a.0.8✓
• b.0.2
• c.1.25
• d.1.0

CPI = EV / AC = 8,000 / 10,000 = 0.8. A CPI below 1.0 means the work is over budget (you earned less value than you spent). CPI is a core earned-value metric for project cost control.

In CPM scheduling, the total float of an activity is correctly computed as:

• a.The activity duration
• b.Early finish minus early start
• c.Late finish minus late start
• d.Late finish minus early finish✓

Total float = Late Finish - Early Finish (equivalently Late Start - Early Start). It is the time an activity can slip without delaying project completion. Activities on the critical path have zero total float.

A soil has a bank (in-place) volume of 100 cubic yards and a swell of 25%. What is the loose (excavated) volume?

• a.80 cubic yards
• b.125 cubic yards✓
• c.75 cubic yards
• d.100 cubic yards

Loose volume = bank volume x (1 + swell) = 100 x 1.25 = 125 cubic yards. Excavating loosens soil so it occupies more volume; swell governs hauling quantities, while shrinkage governs compacted fill.

A concrete slab measures 20 ft by 20 ft by 0.5 ft thick. What volume of concrete is required, in cubic yards?

• a.27 cubic yards
• b.200 cubic yards
• c.7.4 cubic yards✓
• d.3.7 cubic yards

Volume = 20 x 20 x 0.5 = 200 cubic feet. Converting to cubic yards, divide by 27: 200 / 27 = 7.4 cubic yards. Ordering concrete requires this conversion because ready-mix is sold by the cubic yard.

A borrow soil has a bank (in-place) volume of 500 cubic yards and a shrinkage of 10%. What compacted fill volume will it produce?

• a.550 cubic yards
• b.405 cubic yards
• c.450 cubic yards✓
• d.500 cubic yards

Compacted volume = bank volume x (1 - shrinkage) = 500 x (1 - 0.10) = 450 CY. Shrinkage reflects densification of soil in a compacted embankment and governs how much borrow is required for a given fill.

An embankment requires 1,800 compacted cubic yards. If the borrow soil has a shrinkage of 10%, what bank volume must be excavated?

• a.1,800 cubic yards
• b.2,000 cubic yards✓
• c.1,980 cubic yards
• d.1,620 cubic yards

Bank volume = compacted volume / (1 - shrinkage) = 1,800 / 0.90 = 2,000 CY. You must excavate more bank material than the finished fill because compaction reduces the volume.

A soil has a bank volume of 2,000 cubic yards and a swell of 25%. What is the loose (hauled) volume?

• a.2,250 cubic yards
• b.1,600 cubic yards
• c.2,500 cubic yards✓
• d.2,000 cubic yards

Loose volume = bank volume x (1 + swell) = 2,000 x 1.25 = 2,500 CY. Excavation loosens soil so it occupies more volume; swell governs the number of truck loads to haul.

A soil swells 25% when excavated. What is its load factor?

• a.0.80✓
• b.1.00
• c.1.25
• d.0.75

Load factor = 1 / (1 + swell) = 1 / 1.25 = 0.80. Multiplying a loose (truck) volume by the load factor converts it back to bank volume, the basis for pay quantities.

A project must haul 2,500 loose cubic yards of soil in trucks that carry 25 loose cubic yards each. How many truck loads are required?

• a.100 loads✓
• b.50 loads
• c.80 loads
• d.125 loads

Number of loads = total loose volume / truck capacity = 2,500 / 25 = 100 loads. Hauling calculations must use loose (not bank) volume because trucks carry loosened, swelled material.

A front-end loader has a 3-cubic-yard bucket and completes one load cycle in 30 seconds. At 100% efficiency, what is its production rate?

• a.120 CY/hr
• b.720 CY/hr
• c.360 CY/hr✓
• d.180 CY/hr

Cycles per hour = 3,600 s / 30 s = 120; production = 120 x 3 CY = 360 CY/hr. Production is bucket volume times cycles per hour, before applying an efficiency factor.

Applying a 50-minute working hour (efficiency factor 50/60), what is the realistic production of a loader whose ideal output is 360 CY/hr?

• a.300 CY/hr✓
• b.432 CY/hr
• c.250 CY/hr
• d.360 CY/hr

Realistic production = ideal x efficiency = 360 x (50/60) = 300 CY/hr. The 50-minute-hour factor accounts for normal job and management delays within each clock hour.

A haul truck has a total cycle time of 24 minutes, and the loader fills it in 6 minutes. How many trucks are needed to keep the loader working continuously?

• a.6 trucks
• b.4 trucks✓
• c.3 trucks
• d.5 trucks

Number of trucks = truck cycle time / load time = 24 / 6 = 4 trucks. Matching the fleet to the loader's pace avoids the loader idling or trucks queuing.

A haul truck spends 6 min loading, 4 min hauling, 2 min dumping, and 3 min returning. What is its total cycle time?

• a.12 min
• b.18 min
• c.15 min✓
• d.20 min

Cycle time is the sum of all activity times: 6 + 4 + 2 + 3 = 15 min. The full cycle, not just haul time, sets how many trips a truck makes per hour.

A 20-CY truck has a cycle time of 15 minutes. What is its hauling production rate?

• a.20 CY/hr
• b.100 CY/hr
• c.80 CY/hr✓
• d.60 CY/hr

Trips per hour = 60 / 15 = 4; production = 4 x 20 = 80 CY/hr. Truck production equals capacity times trips per hour, driven by the complete cycle time.

In a CPM forward pass, an activity has an early start (ES) of day 5 and a duration of 8 days. What is its early finish (EF)?

• a.3
• b.13✓
• c.8
• d.40

Early finish = early start + duration = 5 + 8 = 13. The forward pass propagates ES and EF from project start to compute the earliest completion.

An activity has an early start of day 6 and a late start of day 10. What is its total float?

• a.6
• b.4✓
• c.0
• d.16

Total float = late start - early start = 10 - 6 = 4 days (equivalently LF - EF). It is the delay an activity can absorb without extending the project.

An activity finishes at early finish day 10, and its only successor has an early start of day 12. What is the activity's free float?

• a.12
• b.10
• c.2✓
• d.22

Free float = (earliest ES of successors) - EF = 12 - 10 = 2 days. Free float is the delay available without disturbing the early start of any following activity.

In CPM, the critical path is best defined as:

• a.the path containing the most activities
• b.the shortest path between start and finish
• c.the continuous path whose activities carry the greatest amount of total float in the network
• d.the longest continuous path of activities through the network✓

The critical path is the longest-duration path through the network; it sets the minimum project duration, and its activities have zero total float. Any delay on it delays the project.

A network has three paths from start to finish: A-B-C = 12 days, A-D-C = 15 days, and A-E = 9 days. What is the project duration?

• a.36 days
• b.15 days✓
• c.12 days
• d.9 days

Project duration equals the longest path (the critical path): A-D-C = 15 days. Paths are not summed; the network finishes only when its longest chain completes.

An activity costs $10,000 for a normal 10-day duration or $14,000 crashed to 8 days. What is its crash cost slope?

• a.$500 per day
• b.$2,000 per day✓
• c.$1,000 per day
• d.$4,000 per day

Cost slope = (crash cost - normal cost) / (normal duration - crash duration) = (14,000 - 10,000) / (10 - 8) = $2,000/day. It is the cost to shorten the activity by one day.

An activity has zero total float. What does this indicate?

• a.it has the maximum scheduling flexibility of any activity in the network
• b.it is not yet scheduled
• c.it can be delayed freely
• d.any delay to it delays the whole project✓

Zero total float means the activity is on the critical path, so any slip pushes the project completion out. Critical activities receive priority for resources and monitoring.

Using the full-liquid-head assumption, what is the maximum lateral pressure at the base of a 5-ft-tall wall form for concrete weighing 150 pcf?

• a.750 psf✓
• b.600 psf
• c.1,000 psf
• d.375 psf

Treating fresh concrete as a fluid, p = unit weight x height = 150 x 5 = 750 psf. This full-liquid-head value is a conservative upper bound; ACI 347 formulas reduce it for slower placement.

Increasing the rate of concrete placement into a wall form generally does what to the maximum lateral form pressure?

• a.has no effect on form pressure
• b.eliminates the need for form ties
• c.lowers the maximum lateral form pressure
• d.raises the maximum lateral form pressure✓

Faster placement keeps more concrete fluid before initial set, so a greater depth acts hydrostatically and the peak pressure rises. Slower pours let lower lifts stiffen and carry their own weight.

A slab measures 30 ft by 40 ft by 0.5 ft thick. How much concrete is required, in cubic yards?

• a.24 CY
• b.600 CY
• c.20 CY
• d.22.2 CY✓

Volume = 30 x 40 x 0.5 = 600 cubic feet; divide by 27 to get cubic yards: 600 / 27 = 22.2 CY. Ready-mix concrete is ordered by the cubic yard, so this conversion is essential.

A continuous footing is 2 ft wide, 1.5 ft deep, and 100 ft long. What volume of concrete is required, in cubic yards?

• a.11.1 CY✓
• b.9.0 CY
• c.300 CY
• d.7.4 CY

Volume = 2 x 1.5 x 100 = 300 cubic feet; 300 / 27 = 11.1 CY. Always convert cubic feet to cubic yards (divide by 27) before ordering concrete.

A two-leg sling lifts an 8-kip load with each leg at 60 degrees from the horizontal. What is the tension in each leg?

• a.8.00 kip
• b.4.62 kip✓
• c.4.00 kip
• d.5.66 kip

Each leg carries half the vertical load (4 kip); tension = vertical share / sin(angle) = 4 / sin 60 = 4 / 0.866 = 4.62 kip. Sling tension always exceeds the shared vertical load.

A two-leg sling lifts a 10-kip load with each leg at 45 degrees from horizontal. What is the tension in each leg?

• a.5.00 kip
• b.3.54 kip
• c.10.0 kip
• d.7.07 kip✓

Vertical share per leg = 10 / 2 = 5 kip; tension = 5 / sin 45 = 5 / 0.707 = 7.07 kip. The flatter the sling, the higher the tension for the same load.

As the angle between a sling leg and the horizontal decreases (the sling flattens), the tension in each leg:

• a.tension decreases
• b.the load capacity increases
• c.tension increases✓
• d.tension stays constant

Leg tension = vertical share / sin(angle); as the angle drops, sin decreases and tension climbs sharply. This is why rigging charts warn against very flat sling angles.

For a mobile crane, the rated lifting capacity generally:

• a.decreases as load radius increases✓
• b.is independent of load radius
• c.increases as load radius increases
• d.depends only on boom length

Capacity is governed by the tipping/structural moment, so as the load radius (horizontal distance to the load) grows, the allowable load falls. Load charts list capacity versus radius.

A round concrete column is 24 in in diameter and 10 ft tall. How much concrete does it need, in cubic yards?

• a.3.14 CY
• b.1.16 CY✓
• c.0.58 CY
• d.31.4 CY

Cross-section area = pi x (1 ft)^2 = 3.14 sq ft; volume = 3.14 x 10 = 31.4 cubic feet; 31.4 / 27 = 1.16 CY. The radius is 1 ft (half of the 24-in diameter).

A road section 1,000 ft long and 24 ft wide receives a 0.5-ft-thick asphalt layer weighing 145 pcf. How many tons of asphalt are required?

• a.870 tons✓
• b.435 tons
• c.960 tons
• d.1,740 tons

Volume = 1,000 x 24 x 0.5 = 12,000 cubic feet; weight = 12,000 x 145 = 1,740,000 lb; tons = 1,740,000 / 2,000 = 870 tons. Asphalt is bid and paid by the ton.

A field-compacted soil has a dry density of 118 pcf; the maximum Proctor dry density is 125 pcf. What is the relative compaction?

• a.94.4%✓
• b.90%
• c.106%
• d.88%

Relative compaction = field dry density / max dry density x 100 = 118 / 125 x 100 = 94.4%. Specifications commonly require 90% to 95% of the Proctor maximum.

A specification requires 95% relative compaction, and the maximum Proctor dry density is 120 pcf. What field dry density must be achieved?

• a.114 pcf✓
• b.120 pcf
• c.108 pcf
• d.126 pcf

Required density = 0.95 x maximum dry density = 0.95 x 120 = 114 pcf. Nuclear-gauge or sand-cone tests verify that field density meets this target.

A sheepsfoot (padfoot) roller is best suited for compacting which material?

• a.crushed rock
• b.cohesive clay✓
• c.gravel
• d.clean uniformly graded sand placed in thick lifts

The feet knead and remold cohesive clay/silt, compacting it from the bottom of the lift up. Smooth-drum and vibratory rollers are preferred for granular soils, where kneading is unnecessary.

A crew of 4 workers places 40 cubic yards of concrete in an 8-hour shift. What is the labor productivity?

• a.1.25 CY/labor-hr✓
• b.0.8 CY/labor-hr
• c.10 CY/labor-hr
• d.5 CY/labor-hr

Productivity = output / labor-hours = 40 / (4 x 8) = 40 / 32 = 1.25 CY per labor-hour. Labor-hours, not crew-hours, are the denominator for unit productivity.

A crew costing $400 per hour places concrete at 50 CY per hour. What is the unit labor cost?

• a.$0.125/CY
• b.$20/CY
• c.$12.50/CY
• d.$8.00/CY✓

Unit cost = crew cost per hour / production per hour = 400 / 50 = $8.00/CY. Dividing an hourly crew rate by hourly production yields cost per unit of work.

A contractor's direct cost is $100,000 and applies a 15% markup on cost. What is the bid price?

• a.$85,000
• b.$117,647
• c.$15,000
• d.$115,000✓

Bid = direct cost x (1 + markup) = 100,000 x 1.15 = $115,000. Markup-on-cost adds the percentage to the cost, unlike margin-on-price which divides by (1 - margin).

A contractor wants a 20% profit margin on the selling price for a job costing $80,000. What price achieves this?

• a.$120,000
• b.$66,667
• c.$96,000
• d.$100,000✓

Price = cost / (1 - margin) = 80,000 / (1 - 0.20) = 80,000 / 0.80 = $100,000. A margin on price is not the same as a markup on cost; applying 20% to cost ($96,000) understates the price.

In a construction estimate, a contingency allowance represents:

• a.a reserve for identified but uncertain costs✓
• b.the contractor's fee
• c.guaranteed profit that the contractor keeps regardless of how the work turns out
• d.a bonus for early finish

Contingency covers foreseeable but not fully quantified risks (quantity growth, minor unknowns) within the defined scope. It is not profit and is drawn down as risks materialize.

A task has an earned value (EV) of $12,000 and a planned value (PV) of $15,000. What is the Schedule Performance Index (SPI)?

• a.0.20
• b.0.80✓
• c.1.25
• d.1.0

SPI = EV / PV = 12,000 / 15,000 = 0.80. An SPI below 1.0 means less work was accomplished than planned, so the project is behind schedule.