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MD Land Surveyor practice questions

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Question 1Land Surveying Fundamentals

In the U.S. Public Land Survey System, a township is nominally a square tract of land measuring how many miles on each side?

  1. 6 miles Correct answer.
  2. 1 mile
  3. 24 miles
  4. 12 miles

Explanation

A PLSS township is nominally 6 miles on a side, containing 36 sections of one square mile each. Sections are numbered from the northeast corner, serpentine, ending at 36 in the southeast corner. This six-mile framework is the basis for the rectangular survey system.

Question 2Land Surveying Fundamentals

A bearing of N 45° E is equivalent to which azimuth measured clockwise from north?

  1. 315°
  2. 225°
  3. 45° Correct answer.
  4. 135°

Explanation

Azimuths are measured clockwise from north through 360°, so a northeast bearing of exactly 45° east of north corresponds to an azimuth of 45°. The quadrant bearing and the azimuth coincide only at this diagonal. Converting requires adding or subtracting the bearing angle from the appropriate cardinal direction.

Question 3Land Surveying Fundamentals

On a survey plat, the scale is stated as 1 inch equals 100 feet. A line scaled on the plat measures 3.5 inches. What is the ground distance?

  1. 3,500 feet
  2. 350 inches
  3. 350 feet Correct answer.
  4. 35 feet

Explanation

At 1 inch to 100 feet, each inch on the plat represents 100 feet on the ground. Multiplying 3.5 inches by 100 feet per inch gives 350 feet. The units must be kept consistent, so the answer is expressed in feet, not inches.

Question 4Land Surveying Fundamentals

In differential leveling, what is the term for a temporary instrument setup position from which backsight and foresight readings are taken?

  1. Height of instrument
  2. Turning point
  3. Instrument station Correct answer.
  4. Bench mark

Explanation

The instrument station is the location where the level is set up for a set of readings. The height of instrument is the elevation of the line of sight, not the physical setup location. A turning point is a point on which two readings are taken to continue the run.

Question 5Land Surveying Fundamentals

A closed traverse that returns to its starting point should have a total interior angle sum equal to which value for a five-sided polygon?

  1. 360°
  2. 540° Correct answer.
  3. 180°
  4. 720°

Explanation

The interior angles of a closed polygon sum to (n−2)×180°, where n is the number of sides. For n = 5 this yields 3×180° = 540°. This closure check reveals angular misclosure before coordinates are computed.

Question 6Land Surveying Fundamentals

Which term describes the angular difference between true north and magnetic north at a given location?

  1. Magnetic declination Correct answer.
  2. Deflection angle
  3. Azimuth
  4. Grid convergence

Explanation

Magnetic declination is the angle between true (geographic) north and magnetic north and changes with location and time. Grid convergence, by contrast, is the angle between true north and grid north on a projection. Surveyors must apply declination to convert magnetic bearings to true bearings.

Question 7Land Surveying Fundamentals

What does the abbreviation "BM" denote on a survey drawing or field note set?

  1. Boundary monument
  2. Base map
  3. Bench mark Correct answer.
  4. Baseline measurement

Explanation

BM stands for bench mark, a point of known or assumed elevation used as a reference for leveling. Bench marks anchor vertical control for a project. Other abbreviations such as MON denote monuments used for horizontal control.

Question 8Land Surveying Fundamentals

A distance measured along a slope is 100.00 feet, and the vertical elevation difference between its ends is 6.00 feet. What is the horizontal distance, to the nearest 0.01 foot?

  1. 99.82 ft Correct answer.
  2. 94.00 ft
  3. 106.00 ft
  4. 99.99 ft

Explanation

Horizontal distance is the hypotenuse reduced by the Pythagorean relationship: H = √(S² − V²) = √(100² − 6²) = √(10,000 − 36) = √9,964 ≈ 99.82 ft. Slope distance is always longer than horizontal distance. The correction is small because the elevation difference is modest.

Question 9Land Surveying Fundamentals

In a differential leveling run, a backsight of 4.25 ft is taken on a point of elevation 100.00 ft. What is the height of instrument?

  1. 100.00 ft
  2. 4.25 ft
  3. 95.75 ft
  4. 104.25 ft Correct answer.

Explanation

Height of instrument equals the known elevation plus the backsight reading: 100.00 + 4.25 = 104.25 ft. This HI is then used to compute foresight elevations by subtraction. Confusing the sign of the operation is a common source of leveling error.

Question 10Land Surveying Fundamentals

A total station measures a slope distance of 250.000 m with a zenith angle of 90°00'00". What horizontal distance results?

  1. 176.777 m
  2. 353.553 m
  3. 0.000 m
  4. 250.000 m Correct answer.

Explanation

A zenith angle of 90° means the line of sight is horizontal, so slope distance equals horizontal distance. Horizontal distance equals slope distance times sin(zenith); sin 90° = 1. Any deviation from 90° would reduce the horizontal component.

Question 11Land Surveying Fundamentals

What is the primary purpose of a traverse adjustment such as the compass (Bowditch) rule?

  1. To convert bearings to azimuths
  2. To determine the elevation of turning points
  3. To correct magnetic declination
  4. To distribute linear misclosure proportionally to leg lengths Correct answer.

Explanation

The compass rule distributes the linear misclosure of a closed traverse among the legs in proportion to their lengths. This forces the traverse to close on its starting coordinates. It addresses horizontal position only, not elevations or angular reference.

Question 12Land Surveying Fundamentals

A deed describes a boundary as running "thence North 30°00'00" East a distance of 200.00 feet." What are the approximate latitude and departure of this course?

  1. Latitude 100.00 ft, departure 173.21 ft
  2. Latitude 173.21 ft, departure 100.00 ft Correct answer.
  3. Latitude 200.00 ft, departure 0.00 ft
  4. Latitude 141.42 ft, departure 141.42 ft

Explanation

Latitude equals distance times cosine of the bearing angle and departure equals distance times sine. Here 200×cos30° ≈ 173.21 ft north and 200×sin30° = 100.00 ft east. Latitude is the north-south component and departure the east-west component.

Question 13Land Surveying Fundamentals

In GNSS surveying, which technique achieves centimeter-level accuracy by resolving carrier-phase integer ambiguities using corrections from a nearby reference station?

  1. Real-time kinematic (RTK) Correct answer.
  2. Standard positioning service
  3. Dead reckoning
  4. Autonomous point positioning

Explanation

RTK uses carrier-phase measurements and corrections from a base station or network to resolve integer ambiguities, yielding centimeter-level positions in real time. Autonomous positioning uses code measurements alone and is far less precise. The reference station provides the differential corrections that make ambiguity resolution possible.

Question 14Land Surveying Fundamentals

A closed leveling loop begins and ends on a bench mark of elevation 500.000 ft. The sum of backsights is 28.450 ft and the sum of foresights is 28.485 ft. What is the misclosure?

  1. 0.035 ft Correct answer.
  2. 0.350 ft
  3. 0.035 ft per setup
  4. 56.935 ft

Explanation

Misclosure equals the sum of backsights minus the sum of foresights: 28.450 − 28.485 = −0.035 ft, a magnitude of 0.035 ft. A perfect run would give zero difference. This residual is compared against the allowable closure for the project.

Question 15Land Surveying Fundamentals

Which of the following best describes a "monument" in boundary surveying?

  1. A computed coordinate pair
  2. A physical object set to mark a boundary corner or line Correct answer.
  3. A temporary tripod setup
  4. A written record of a previous survey

Explanation

A monument is a physical object, such as an iron pin, concrete post, or stone, placed to mark a corner or line on the ground. Monuments are the physical evidence that controls boundary location. Coordinates and written records are representations, not the monument itself.

Question 16Land Surveying Fundamentals

A surveyor measures the same distance six times and obtains values tightly clustered around one figure that is later found to be 0.5 ft from the true value. What do these observations demonstrate?

  1. Neither precision nor accuracy
  2. High accuracy but low precision
  3. Both high accuracy and high precision
  4. High precision but low accuracy Correct answer.

Explanation

Precision describes how closely repeated measurements agree with one another, while accuracy describes closeness to the true value. Tight clustering with a consistent offset from truth indicates good precision but a systematic bias degrading accuracy. Calibration or instrument checks would address the bias.

Question 17Land Surveying Fundamentals

What is the function of a plumb bob or optical plummet when setting up an instrument over a survey point?

  1. To level the horizontal axis of the instrument
  2. To center the instrument vertically over the ground mark Correct answer.
  3. To measure the height of the instrument
  4. To record the magnetic bearing

Explanation

A plumb bob or optical plummet projects the instrument's vertical axis to the ground so it can be centered over the mark. Leveling is a separate operation performed with the leveling screws and bubble. Centering and leveling together ensure the instrument occupies the correct point.

Question 18Land Surveying Fundamentals

A parcel is described as the "NE 1/4 of the SW 1/4 of Section 12." What is the nominal area of this tract?

  1. 10 acres
  2. 40 acres Correct answer.
  3. 80 acres
  4. 160 acres

Explanation

Each quarter-quarter aliquot part of a one-square-mile section contains 640 ÷ 16 = 40 acres. The NE 1/4 of the SW 1/4 is one such 40-acre tract. Aliquot parts are named by successive halving of the section.

Question 19Land Surveying Fundamentals

In a boundary survey, which rule holds that a natural monument generally controls over a course and distance called for in the deed?

  1. The rule of monuments controlling over courses and distances Correct answer.
  2. The rule of adverse possession
  3. The rule of senior rights
  4. The rule of proportionate measurement

Explanation

A well-established principle of boundary evidence holds that natural or artificial monuments called for in a deed generally control over recited courses and distances. Distances are considered the least reliable element of a description. This hierarchy guides resolution when the record and field evidence conflict.

Question 20Land Surveying Fundamentals

A total station occupies Station A and sights Station B, 500.000 ft away, with an azimuth of 90°00'00". A point P is then set at an azimuth of 135°00'00" from A. What is the angle turned from AB to AP?

  1. 225°00'00"
  2. 135°00'00"
  3. 90°00'00"
  4. 45°00'00" Correct answer.

Explanation

The angle between two directions from the same station is the difference of their azimuths: 135° − 90° = 45°. Azimuths are measured from the same north reference, so subtraction gives the turned angle directly. This is the basis for setting out by angle from a backsight.

Question 21Land Surveying Fundamentals

In a closed traverse, the sum of latitudes is +0.12 ft and the sum of departures is −0.08 ft. What is the linear misclosure?

  1. 0.144 ft Correct answer.
  2. 0.02 ft
  3. 0.20 ft
  4. 0.04 ft

Explanation

Linear misclosure is the vector magnitude of the latitude and departure residuals: √(0.12² + 0.08²) = √(0.0144 + 0.0064) = √0.0208 ≈ 0.144 ft. The residuals act as perpendicular components, so they combine by the Pythagorean theorem rather than by direct addition.

Question 22Land Surveying Fundamentals

A surveyor must convert a magnetic bearing observed today to a true bearing. The observed magnetic bearing is N 10°00' E and magnetic declination is 5°00' E. What is the true bearing?

  1. N 15°00' E Correct answer.
  2. N 10°00' E
  3. N 5°00' E
  4. N 15°00' W

Explanation

East declination means magnetic north lies east of true north, so a true bearing is found by adding east declination to the magnetic bearing: 10° + 5° = 15° east of true north. West declination would be subtracted. Keeping the sign of declination straight is essential to avoid a systematic error.

Question 23Land Surveying Fundamentals

A deed calls for a line "to a stone at the bank of a creek, thence with the creek." The stone cannot be found, but the creek exists as described. How should the surveyor treat the boundary evidence?

  1. Disregard the creek because the stone is missing
  2. Average the deed distance and the creek location
  3. Use the stated distance alone to establish the corner
  4. Use the creek as the controlling natural monument Correct answer.

Explanation

The creek is a natural monument called for in the deed and generally controls over courses and distances. The missing stone does not eliminate the creek as evidence of the intended boundary. The surveyor should follow the natural feature as described.

Question 24Land Surveying Fundamentals

In a leveling run of 10 setups, each backsight and foresight reading is subject to a random error of ±0.005 ft. Assuming errors are independent, what is the approximate expected error in the total elevation difference?

  1. ±0.100 ft
  2. ±0.022 ft Correct answer.
  3. ±0.050 ft
  4. ±0.005 ft

Explanation

Random errors accumulate by the square root of the number of observations. With 10 setups each contributing a reading error, the combined error is approximately 0.005×√(2×10) ≈ 0.022 ft when both backsight and foresight errors are considered. This illustrates why random error grows more slowly than the number of setups.

Question 25Land Surveying Fundamentals

A surveyor computes coordinates for a closed traverse and finds that the adjusted traverse closes exactly but the computed area differs from the deed area by 2%. Which statement best characterizes the situation?

  1. Closure of the traverse does not by itself validate the area against the deed Correct answer.
  2. The area discrepancy proves the deed is wrong
  3. The coordinates must be recomputed until the area matches the deed
  4. A forced mathematical closure guarantees the field measurements were accurate

Explanation

An adjustment distributes misclosure but cannot create accuracy that the field measurements lacked. A traverse can close mathematically while still containing systematic error that shifts the computed area. The surveyor should evaluate measurement quality independently rather than assuming closure validates the result.

Question 26Land Surveying Fundamentals

In the Public Land Survey System, a township is nominally how wide, measured east-west along a standard parallel?

  1. One mile
  2. Thirty-six miles
  3. Six miles Correct answer.
  4. Twelve miles

Explanation

A PLSS township is a six-mile-square block subdivided into 36 sections, each nominally one mile square. The east-west extent between the governing meridians is therefore six miles, subject to correction lines.

Question 27Land Surveying Fundamentals

Which angular unit equals exactly 1/3600 of one degree?

  1. One second of arc Correct answer.
  2. One radian
  3. One grad
  4. One minute of arc

Explanation

Angle notation in surveying uses degrees, minutes, and seconds, where one degree contains 60 minutes and each minute contains 60 seconds. One second is therefore 1/3600 of a degree.

Question 28Land Surveying Fundamentals

A bearing is written as S 45°00'00" W. Into which quadrant does the line run?

  1. Northwest
  2. Southwest Correct answer.
  3. Southeast
  4. Northeast

Explanation

The first letter of a quadrant bearing gives the north or south component and the second gives the east or west component. S and W together place the line in the southwest quadrant, 45 degrees west of due south.

Question 29Land Surveying Fundamentals

What does a surveyor call the temporary turning point used between two instrument setups in a differential leveling run?

  1. A bench mark
  2. A turning point Correct answer.
  3. A reference mark
  4. A temporary benchmark

Explanation

A turning point is a stable, unmarked point on which a foresight is taken and then a backsight is taken after the instrument is moved. It carries the elevation forward without being a permanent elevation reference.

Question 30Land Surveying Fundamentals

On a plat, a curved boundary is annotated with a radius, a central angle, and an arc length. Which additional element is normally shown to fully define the curve?

  1. The magnetic declination
  2. The convergence angle
  3. The grid azimuth only
  4. The chord bearing and chord length Correct answer.

Explanation

A circular curve is fully described by its radius, central angle, arc length, and the chord bearing and chord length between the tangent points. The chord data let the reader compute and check the endpoint coordinates.

Question 31Land Surveying Fundamentals

Which instrument is designed primarily to measure horizontal and vertical angles with high precision and, when fitted with a distance meter, also measures distances?

  1. Total station Correct answer.
  2. Hand level
  3. Plane table
  4. Automatic level

Explanation

A total station combines an electronic theodolite with an electronic distance meter and onboard computing. It measures angles and distances to a target and can reduce them to coordinates.

Question 32Land Surveying Fundamentals

In a metes-and-bounds description, what does the word 'metes' refer to?

  1. The recording stamp of the county
  2. The names of adjoining owners
  3. The bearings and distances of the boundary lines Correct answer.
  4. The area of the parcel

Explanation

Metes are the courses, meaning bearings and distances, while bounds are the physical monuments or adjoiners that call for the lines. Together they describe the parcel boundary.

Question 33Land Surveying Fundamentals

Which map projection is commonly used for state plane coordinate systems because it keeps scale error small over a limited zone?

  1. A polar stereographic projection
  2. A sinusoidal equal-area projection
  3. A Mercator projection centered on the equator
  4. A transverse Mercator or Lambert conformal conic projection Correct answer.

Explanation

State plane systems use conformal projections, typically transverse Mercator for north-south zones and Lambert conformal conic for east-west zones. Conformality preserves angles and keeps scale distortion small within a narrow zone.

Question 34Land Surveying Fundamentals

A total station reads a zenith angle of 60°00'00" to a target at a slope distance of 200.000 m. Treating the instrument and target heights as equal, what is the horizontal distance?

  1. 100.000 m Correct answer.
  2. 173.205 m
  3. 200.000 m
  4. 86.603 m

Explanation

Horizontal distance equals slope distance times the sine of the zenith angle, since the zenith is measured from the vertical. Here 200.000 × sin 60° = 200.000 × 0.86603 = 173.205 m, so the option 173.205 m is the correct value and the keyed answer is the one matching it.

Question 35Land Surveying Fundamentals

A line has a latitude of +150.000 ft and a departure of −150.000 ft. What is its azimuth measured clockwise from north?

  1. 135°00'00" Correct answer.
  2. 225°00'00"
  3. 45°00'00"
  4. 315°00'00"

Explanation

A positive latitude means the line runs north and a negative departure means it runs west, placing it in the northwest quadrant. Equal magnitudes give a 45-degree angle west of north, which as an azimuth is 360 − 45 = 315 degrees.

Question 36Land Surveying Fundamentals

A closed traverse has a total angular error of 0°01'30" distributed among six interior angles. What is the correction applied to each angle if the error is distributed equally?

  1. 0°01'30"
  2. 0°00'15" Correct answer.
  3. 0°00'30"
  4. 0°00'25"

Explanation

Equal distribution divides the total angular misclosure by the number of angles. Ninety seconds divided by six angles gives fifteen seconds per angle, applied with the sign opposite the misclosure.

Question 37Land Surveying Fundamentals

A level is set up midway between two points 300 ft apart, and the rod readings are 3.500 ft on the near point and 5.250 ft on the far point. What is the elevation difference between the points?

  1. 1.750 ft, with the far point higher Correct answer.
  2. 0.571 ft, with the far point higher
  3. 1.750 ft, with the far point lower
  4. 8.750 ft, with the far point lower

Explanation

The larger rod reading occurs on the lower point, since the line of sight is horizontal. The far point reads 1.750 ft higher on the rod, so it lies 1.750 ft lower in elevation than the near point, meaning the near point is higher.

Question 38Land Surveying Fundamentals

A surveyor measures a distance as 528.000 ft with a 100-ft steel tape that is actually 100.020 ft long under field conditions. What is the corrected distance?

  1. 527.980 ft
  2. 528.020 ft
  3. 528.106 ft Correct answer.
  4. 527.894 ft

Explanation

The correction equals the measured length times the tape error divided by the nominal tape length. Here 528.000 × 0.020/100 = 0.106 ft, and because the tape is long the measured value is increased, giving 528.106 ft.

Question 39Land Surveying Fundamentals

A boundary line bears N 20°00'00" E. What is the equivalent azimuth measured clockwise from south?

  1. 20°00'00"
  2. 200°00'00" Correct answer.
  3. 340°00'00"
  4. 160°00'00"

Explanation

An azimuth from south is measured clockwise starting at due south, which is 180 degrees in the north-based system. Converting the north-based azimuth of 20 degrees gives 180 + 20 = 200 degrees.

Question 40Land Surveying Fundamentals

A rectangular parcel measures 250.00 m by 400.00 m. What is its area in hectares?

  1. 0.100 ha
  2. 1.000 ha
  3. 10.000 ha Correct answer.
  4. 100.000 ha

Explanation

The area is 250 × 400 = 100,000 square meters. One hectare equals 10,000 square meters, so the parcel contains 10.000 hectares.

Question 41Land Surveying Fundamentals

Why is a closed traverse generally preferred over an open traverse for control work?

  1. It eliminates the need for any angular measurement
  2. It provides a mathematical check on both angular and linear misclosure Correct answer.
  3. It requires no monumentation of stations
  4. It automatically corrects for magnetic declination

Explanation

A closed traverse returns to a known point, so the surveyor can compare computed closure against known coordinates. That comparison reveals accumulated angular and linear error, which an open traverse cannot expose.

Question 42Land Surveying Fundamentals

A GNSS receiver collects static observations on two points for 45 minutes and post-processes the data against a continuously operating reference station. Which error source is most reduced by differential processing?

  1. Antenna height measurement blunders
  2. Receiver firmware version mismatches
  3. Satellite orbit and clock errors common to both receivers Correct answer.
  4. Local multipath at the rover antenna

Explanation

Differential processing cancels errors that are common to the base and rover, principally satellite clock and orbit errors and much of the atmospheric delay. Errors unique to one receiver, such as local multipath, are not removed.

Question 43Land Surveying Fundamentals

In a boundary retracement, the original survey called for a line to run to 'a white oak, 18 inches in diameter.' The oak is gone but a stump of matching size and species remains at the described location. How is the stump generally treated?

  1. As controlling evidence of the original corner, since it is the remains of the called-for monument Correct answer.
  2. As meaningless because the tree no longer stands
  3. As inferior to the record distance in all cases
  4. As a new monument that supersedes the original deed call

Explanation

Monument controls over course and distance, and the remains of the called-for monument are strong evidence of the original corner location. A stump matching the species, size, and position supports the corner as originally set.

Question 44Land Surveying Fundamentals

A deed calls for a parcel bounded by a meandering non-navigable stream. Under the common-law rule for non-navigable streams, the boundary of a riparian owner typically extends to which location?

  1. The thread (centerline) of the stream Correct answer.
  2. The ordinary high water mark
  3. The low water mark
  4. The nearest public road right-of-way

Explanation

Under the common-law rule, owners of land bordering a non-navigable stream hold title to the thread or centerline of the stream, subject to the water. Navigable waters follow a different rule keyed to the ordinary high water mark.

Question 45Land Surveying Fundamentals

A surveyor must stake a point 75.000 ft from a total station along an azimuth of 210°00'00". What are the approximate north and east offsets of that point from the instrument?

  1. South 37.500 ft, West 64.952 ft
  2. North 37.500 ft, East 64.952 ft
  3. South 64.952 ft, West 37.500 ft Correct answer.
  4. North 64.952 ft, East 37.500 ft

Explanation

Latitude equals distance times the cosine of the azimuth and departure equals distance times the sine. At 210 degrees both cosine and sine are negative, giving 75 × (−0.86603) = −64.952 ft north and 75 × (−0.50000) = −37.500 ft east.

Question 46Land Surveying Fundamentals

A level circuit closes with a misclosure of 0.048 ft over a route of 1.2 miles. What is the misclosure expressed in feet per mile?

  1. 0.058 ft/mi
  2. 0.400 ft/mi
  3. 0.048 ft/mi
  4. 0.040 ft/mi Correct answer.

Explanation

Dividing the total misclosure by the route length gives the rate per mile. Here 0.048 ft divided by 1.2 miles equals 0.040 ft per mile, which can be compared against the project's closure standard.

Question 47Land Surveying Fundamentals

A survey crew observes a horizontal angle four times, reading 47°12'20", 47°12'40", 47°12'25", and 47°12'35". What is the mean angle?

  1. 47°12'30" Correct answer.
  2. 47°12'35"
  3. 47°12'40"
  4. 47°12'25"

Explanation

Summing the four readings gives 188°49'60", which is 188°50'00". Dividing by four yields 47°12'30", the arithmetic mean of the observations.

Question 48Land Surveying Fundamentals

An angle is measured as 89°59'40" when its true value is 90°00'00". How should this observation be characterized?

  1. It has high precision but a systematic error of 20 seconds Correct answer.
  2. It has an accuracy of 20 seconds and unknown precision
  3. It contains a 20-second blunder
  4. It is both precise and accurate within 1 second

Explanation

Accuracy describes closeness to the true value, while precision describes repeatability among observations. A consistent 20-second departure from truth indicates a systematic error, such as instrument adjustment, rather than random scatter.

Question 49Land Surveying Fundamentals

A closed traverse of five courses has a linear misclosure of 0.150 ft and a total perimeter of 2,500.00 ft. What is the relative precision, expressed as a ratio?

  1. 1:166,670
  2. 1:16,667 Correct answer.
  3. 1:15,000
  4. 1:2,500

Explanation

Relative precision is the perimeter divided by the linear misclosure. Dividing 2,500.00 by 0.150 gives 16,667, so the closure is expressed as 1:16,667.

Question 50Land Surveying Fundamentals

A surveyor must establish control in a dense urban canyon where GNSS signals are blocked and lines of sight are short. Which approach best provides reliable horizontal control under these conditions?

  1. A single sun-shot azimuth with no angular check
  2. A static GNSS session on each corner of the block
  3. A closed traverse with total station observations between intervisible monuments Correct answer.
  4. An open traverse run from one known point to the work area

Explanation

Where satellite signals are obstructed, a closed traverse between intervisible monuments provides redundant angular and linear observations that can be checked and adjusted. Closing the traverse on known control exposes error that an open traverse would hide.