Mixed Deck — All FS Topics Flashcards

What is a Benchmark (BM)?

Answer: A point of known elevation

Explanation: A benchmark (BM) is a point of known elevation. It is a reference point used in surveying and construction to establish vertical measurements. By knowing the elevation of a benchmark, surveyors can accurately determine the elevation of other points in the area. This helps in ensuring that structures are built at the correct height and that accurate measurements are taken for various purposes.

What does PDOP measure in GPS quality assessment?

Answer: Position Dilution of Precision

PDOP (Position Dilution of Precision) describes the combined effect of satellite geometry on 3D positional accuracy.

The arc length (L) of a simple horizontal curve with radius R and central angle Δ expressed in radians is:

Answer: L = R × Δ

Arc length equals the radius multiplied by the central angle in radians: L = R × Δ.

A crest vertical curve is used when:

Answer: A positive grade is followed by a negative or less steep positive grade

A crest (summit) vertical curve occurs when the algebraic difference in grades produces a curve that is concave downward, connecting a positive grade to a negative or flatter grade.

What does the term 'sounding' refer to in hydrographic surveying?

Answer: A depth measurement below the water surface

A sounding is a measurement of water depth at a specific location, referenced to a chart datum and plotted on nautical charts.

The rights of a landowner whose property abuts a flowing river are known as:

Answer: Riparian rights

Riparian rights pertain to landowners whose property is adjacent to a flowing body of water, like a river or stream. Littoral rights apply to landowners whose property borders a static body of water, such as a lake or ocean. Avulsion is the sudden change in a river's course and relates to how boundaries are affected, but it is not the name of the rights themselves. Subsurface rights relate to ownership of resources below the ground.

In a GIS, which data model is best suited for representing continuous phenomena like elevation, temperature, or satellite imagery?

Answer: Raster

The raster data model uses a grid of cells (or pixels), where each cell contains a value representing the phenomenon being measured. This structure is ideal for representing continuous surfaces where values change across a landscape, such as elevation from a Digital Elevation Model (DEM) or temperature gradients.

In establishing a high-precision horizontal control network, a surveyor includes numerous redundant measurements, such as observing all angles in a quadrilateral and both of its diagonals. What is the primary benefit of incorporating this redundancy into the survey?

Answer: It allows for a rigorous statistical analysis and least-squares adjustment to increase overall accuracy.

Redundant measurements are essential for a robust control survey because they provide more data than is minimally required to determine the positions of the points. [12, 13] This over-determination allows for a least-squares adjustment, which is a statistical method that analyzes the measurements, distributes random errors, helps detect blunders, and computes the most probable coordinate values for the network stations, thereby increasing the overall precision and reliability of the survey. [19, 22]

Which of the following best describes the key characteristic of an orthophoto that distinguishes it from a standard unrectified aerial photograph?

Answer: It has been geometrically corrected to have a uniform scale.

A standard aerial photograph has scale variations and relief displacement due to terrain and perspective geometry. An orthophoto is a photograph that has been geometrically corrected ('orthorectified') to remove these distortions. The result is an image with a uniform scale, similar to a map, where true distances can be measured directly.

The tangent length (T) of a simple horizontal curve with radius R and intersection angle Δ is calculated as:

Answer: T = R × tan(Δ/2)

The tangent length is T = R × tan(Δ/2), derived from the right triangle formed by the radius, tangent, and line to the PI.

A surveyor is performing a closed traverse survey. After measuring all interior angles and distances, they compute the latitudes and departures and find a linear misclosure. Which of the following methods is commonly used to adjust the latitudes and departures to achieve a mathematically closed figure?

Answer: Compass Rule (Bowditch Method)

The Compass Rule, also known as the Bowditch Method, is a standard and widely accepted method for adjusting a closed traverse. It distributes the linear misclosure among the latitudes and departures of the traverse legs in proportion to the length of the legs themselves.

A simple circular horizontal curve has a radius of 1000.00 ft and a central angle (delta) of 30°00'00". What is the length of the tangent (T) from the Point of Intersection (PI) to the Point of Curvature (PC)?

Answer: 267.95 ft

The formula for the tangent length (T) of a simple circular curve is T = R * tan(Δ/2). Given R = 1000.00 ft and Δ = 30°00'00". First, divide the central angle by two: Δ/2 = 15°00'00". Then, calculate the tangent: T = 1000.00 * tan(15°) = 1000.00 * 0.267949 ≈ 267.95 ft. [6, 11, 25]

In earthwork economics, 'overhaul' is best defined as:

Answer: The transportation of excavated material beyond the free haul distance, billed per station-yard or ton-mile

Overhaul is the extra compensation paid when material must be moved farther than the free haul distance, typically measured in station-yards (volume × distance beyond free haul) or ton-miles.

What is multibeam sonar used for in hydrographic surveys?

Answer: Collecting depth profiles across a wide swath simultaneously

Multibeam sonar emits many acoustic beams simultaneously to map a wide swath of the seafloor, providing complete bottom coverage in a single pass.

What is RTK in GPS surveying?

Answer: Real-Time Kinematics

RTK (Real-Time Kinematics) is a differential GPS technique that delivers centimeter-level accuracy in real time by transmitting corrections from a base station to a rover.

A surveyor needs to calculate the volume of earthwork between two parallel cross-sections. The area of the first cross-section (A1) is 450 sq ft and the area of the second cross-section (A2) is 550 sq ft. The distance (L) between the sections is 100 ft. Which of the following formulas is most commonly used for this calculation and what is the resulting volume?

Answer: Average End Area Formula, resulting in 50,000 cubic feet

The Average End Area Formula is a widely used and straightforward method for estimating earthwork volumes. It calculates the average area of the two end sections and multiplies it by the distance between them. The calculation is V = L * (A1 + A2) / 2 = 100 ft * (450 sq ft + 550 sq ft) / 2 = 50,000 cubic feet.

What organization publishes official nautical charts for US coastal waters?

Answer: NOAA Office of Coast Survey

NOAA's Office of Coast Survey produces and maintains official nautical charts for US coastal, Great Lakes, and inland waterways.

The Global Positioning System (GPS) provides its raw positional calculations and coordinates natively referenced to which geodetic reference system?

Answer: World Geodetic System 1984 (WGS 84)

The GPS is operated by the U.S. Department of Defense and uses the World Geodetic System 1984 (WGS 84) as its fundamental reference system. All raw GPS positions are computed on the WGS 84 ellipsoid. Coordinates in other datums, such as NAD 83, are derived through mathematical transformations from WGS 84.

In the chord definition of degree of curve, D is the central angle subtended by a chord of what length?

Answer: 100 feet

The chord definition defines D as the central angle subtended by a 100-foot chord, commonly used in railroad surveying in the US.

What is the height of collimation (HOC) for a Level?

Answer: Height of the instrument after setting up

Explanation: The height of collimation (HOC) for a Level refers to the height of the instrument after it has been set up. This is an important measurement in surveying as it allows for accurate leveling and the determination of elevations. By knowing the HOC, surveyors can calculate the difference in elevation between different points on the ground.