Idaho Civil Engineer Examination
Advanced 100-Question Practice Exam
2026 | Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
Question 1
A. Use only the concrete tensile strength
B. Assume the beam is unreinforced
C. Perform a strain-compatibility or equivalent rectangular stress-block analysis
D. Design the reinforcement using the beam's gross moment of inertia only
Answer: C. Perform a strain-compatibility or equivalent rectangular stress-block
analysis
Rationale: The flexural reinforcement must be proportioned from equilibrium
and compatibility using the applicable reinforced-concrete design provisions.
Gross-section properties alone do not establish the required steel area.
,Question 2
A 20-ft simply supported steel beam carries a uniform service load of 1.5 kip/ft,
excluding beam self-weight. What is the maximum service-load bending moment?
A. 37.5 kip-ft
B. 60 kip-ft
C. 75 kip-ft
D. 150 kip-ft
Answer: C. 75 kip-ft
Rationale: For a simply supported beam with uniform load, Mmax = wL²/8 =
1.5(20²)/8 = 75 kip-ft.
Question 3
A soil sample has a saturated unit weight of 125 pcf. At a point 15 ft below the
groundwater table, what is the approximate effective vertical stress if the total
overburden above the point is 1,875 psf?
A. 780 psf
B. 945 psf
C. 1,410 psf
D. 1,875 psf
Answer: B. 945 psf
Rationale: Effective stress equals total stress minus pore-water pressure. Using
γw ≈ 62.4 pcf, u = 15(62.4) = 936 psf, giving approximately 1,875 − 936 = 939 psf,
or about 945 psf depending on rounding.
Question 4
,A roadway embankment is founded on soft saturated clay. Which condition is
most critical for short-term stability immediately after construction?
A. Long-term drained friction
B. Undrained shear strength of the clay
C. Ultimate pavement friction factor
D. Asphalt viscosity
Answer: B. Undrained shear strength of the clay
Rationale: Immediately after rapid loading, saturated clay may behave
essentially undrained, so short-term stability is governed primarily by undrained
shear strength and total-stress behavior.
Question 5
For a highway horizontal curve, increasing the curve radius while maintaining the
same design speed generally:
A. Increases required superelevation
B. Decreases lateral acceleration
C. Increases lateral acceleration
D. Has no effect on vehicle dynamics
Answer: B. Decreases lateral acceleration
Rationale: Lateral acceleration is approximately v²/R. Increasing radius reduces
lateral acceleration for a given speed, generally reducing the demand for
superelevation and side friction.
Question 6
A stormwater detention basin must reduce a peak inflow of 80 cfs to a controlled
discharge of 30 cfs. If the inflow hydrograph were approximated as constant for 1
, hour, what minimum storage would be required under that simplified
assumption?
A. 18,000 ft³
B. 90,000 ft³
C. 180,000 ft³
D. 288,000 ft³
Answer: C. 180,000 ft³
Rationale: The net storage rate is 80 − 30 = 50 cfs. Over 3,600 seconds, storage is
50(3,600) = 180,000 ft³.
Question 7
In a closed conduit flowing full, which hydraulic parameter is most directly
associated with the energy loss caused by wall friction?
A. Manning roughness coefficient
B. Specific gravity only
C. Atmospheric pressure
D. Vapor pressure
Answer: A. Manning roughness coefficient
Rationale: For many open-channel and partially full conduit calculations,
Manning's n represents hydraulic roughness and directly affects friction-related
energy losses.
Question 8
A wastewater treatment plant experiences a sudden increase in influent
ammonia. Which process is principally responsible for converting ammonia
nitrogen to nitrate under aerobic biological treatment?
Advanced 100-Question Practice Exam
2026 | Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
Question 1
A. Use only the concrete tensile strength
B. Assume the beam is unreinforced
C. Perform a strain-compatibility or equivalent rectangular stress-block analysis
D. Design the reinforcement using the beam's gross moment of inertia only
Answer: C. Perform a strain-compatibility or equivalent rectangular stress-block
analysis
Rationale: The flexural reinforcement must be proportioned from equilibrium
and compatibility using the applicable reinforced-concrete design provisions.
Gross-section properties alone do not establish the required steel area.
,Question 2
A 20-ft simply supported steel beam carries a uniform service load of 1.5 kip/ft,
excluding beam self-weight. What is the maximum service-load bending moment?
A. 37.5 kip-ft
B. 60 kip-ft
C. 75 kip-ft
D. 150 kip-ft
Answer: C. 75 kip-ft
Rationale: For a simply supported beam with uniform load, Mmax = wL²/8 =
1.5(20²)/8 = 75 kip-ft.
Question 3
A soil sample has a saturated unit weight of 125 pcf. At a point 15 ft below the
groundwater table, what is the approximate effective vertical stress if the total
overburden above the point is 1,875 psf?
A. 780 psf
B. 945 psf
C. 1,410 psf
D. 1,875 psf
Answer: B. 945 psf
Rationale: Effective stress equals total stress minus pore-water pressure. Using
γw ≈ 62.4 pcf, u = 15(62.4) = 936 psf, giving approximately 1,875 − 936 = 939 psf,
or about 945 psf depending on rounding.
Question 4
,A roadway embankment is founded on soft saturated clay. Which condition is
most critical for short-term stability immediately after construction?
A. Long-term drained friction
B. Undrained shear strength of the clay
C. Ultimate pavement friction factor
D. Asphalt viscosity
Answer: B. Undrained shear strength of the clay
Rationale: Immediately after rapid loading, saturated clay may behave
essentially undrained, so short-term stability is governed primarily by undrained
shear strength and total-stress behavior.
Question 5
For a highway horizontal curve, increasing the curve radius while maintaining the
same design speed generally:
A. Increases required superelevation
B. Decreases lateral acceleration
C. Increases lateral acceleration
D. Has no effect on vehicle dynamics
Answer: B. Decreases lateral acceleration
Rationale: Lateral acceleration is approximately v²/R. Increasing radius reduces
lateral acceleration for a given speed, generally reducing the demand for
superelevation and side friction.
Question 6
A stormwater detention basin must reduce a peak inflow of 80 cfs to a controlled
discharge of 30 cfs. If the inflow hydrograph were approximated as constant for 1
, hour, what minimum storage would be required under that simplified
assumption?
A. 18,000 ft³
B. 90,000 ft³
C. 180,000 ft³
D. 288,000 ft³
Answer: C. 180,000 ft³
Rationale: The net storage rate is 80 − 30 = 50 cfs. Over 3,600 seconds, storage is
50(3,600) = 180,000 ft³.
Question 7
In a closed conduit flowing full, which hydraulic parameter is most directly
associated with the energy loss caused by wall friction?
A. Manning roughness coefficient
B. Specific gravity only
C. Atmospheric pressure
D. Vapor pressure
Answer: A. Manning roughness coefficient
Rationale: For many open-channel and partially full conduit calculations,
Manning's n represents hydraulic roughness and directly affects friction-related
energy losses.
Question 8
A wastewater treatment plant experiences a sudden increase in influent
ammonia. Which process is principally responsible for converting ammonia
nitrogen to nitrate under aerobic biological treatment?
