PS Construction Layout & Staking 2 — Questions and Answers
Question 1: When setting slope stakes for a highway cut section, which measurement is critical for determining the catch point?
- Horizontal distance from centerline to where the cut slope meets natural ground (Correct answer)
- Vertical distance from subgrade to finish grade
- Offset distance from the edge of pavement to the toe of slope
- Depth of excavation at the centerline
Correct answer: Horizontal distance from centerline to where the cut slope meets natural ground
The catch point is where the cut slope intersects natural ground surface, found by measuring horizontal distance from centerline at the calculated slope ratio.
Question 2: A retaining wall footing must be set at elevation 412.75. The instrument HI is 418.32. What rod reading is needed to set the footing elevation?
- 5.57 (Correct answer)
- 6.43
- 4.71
- 831.07
Correct answer: 5.57
The required rod reading = HI − desired elevation = 418.32 − 412.75 = 5.57 ft.
Question 3: For bridge pier layout, which technique is most reliable for establishing pier centerlines over water?
- Intersection from two shore control points using total station (Correct answer)
- Tape measurement from nearest abutment
- GPS single-point positioning
- Level loop from benchmark
Correct answer: Intersection from two shore control points using total station
Intersecting lines of sight from two shore-based control points using a total station provides precise pier centerline location over water without direct access.
Question 4: In road construction staking, what does a blue-top stake indicate?
- Subgrade elevation has been reached at that point (Correct answer)
- The stake marks a utility crossing
- Water table is near the surface
- The fill material is compacted to spec
Correct answer: Subgrade elevation has been reached at that point
A blue-top stake is driven so its top is flush with the design subgrade elevation, giving the grading contractor a visual target.
Question 5: A storm drain inlet is to be located 42.5 ft right of centerline station 18+75. Which field operation locates it correctly?
- Measure along the perpendicular from the centerline stake at 18+75 to 42.5 ft offset (Correct answer)
- Measure 42.5 ft diagonally from the nearest centerline stake
- Set a stake 42.5 ft right of the right-of-way line
- Calculate coordinate intersection then stake with GPS
Correct answer: Measure along the perpendicular from the centerline stake at 18+75 to 42.5 ft offset
Construction offsets are always measured perpendicular to the baseline at the specified station.
Question 6: When staking a building corner using coordinate geometry, the surveyor computes an angle and distance from a control point. What is this layout method called?
- Polar stakeout (Correct answer)
- Resection
- Three-point intersection
- Triangulation
Correct answer: Polar stakeout
Polar stakeout (also called radial stakeout) uses a computed bearing and distance from a known control point to locate a design point.
Question 7: A grade rod reading taken at a proposed manhole rim elevation of 487.30 gives a reading of 3.46. What is the HI of the level?
- 490.76 (Correct answer)
- 483.84
- 484.76
- 491.30
Correct answer: 490.76
HI = elevation + rod reading = 487.30 + 3.46 = 490.76 ft.
PS Construction Layout & Staking 2
When setting slope stakes for a highway cut section, which measurement is critical for determining the catch point?