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ERE (EXTRA REGIMENTAL EMPLOYEES) 371 Exam 2 Standardized 2025 Questions With Full Answers, Exams of Security Analysis

ERE (EXTRA REGIMENTAL EMPLOYEES) 371 Exam 2 Standardized 2025 Questions With Full Answers Upgraded A.

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ERE (EXTRA REGIMENTAL
EMPLOYEES) 371 Exam 2 Standardized
2025 Questions With Full Answers
Upgraded A.
Traverse
Series of lines of known length connected at traverse stations, related by known angles. Stations must
have visibility to next and previous station.
Traversing
Activity of establishing and measuring traverse. Applied as common method for local horizontal control
surveys.
Mathematically Closed Traverse
- Geometrically closed : polygon that begins and ends on same point. Checks: angular measurements
-Geometrically open : begin/end on different points. point locations known better than measurements.
Control station on both ends. Checks: angles and distances.
Mathematically open traverse
Begin and end on unrelated pts. Control station on only 1 end. No checks/ closure so must repeat
measurements. Application: exploratory surveys
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Download ERE (EXTRA REGIMENTAL EMPLOYEES) 371 Exam 2 Standardized 2025 Questions With Full Answers and more Exams Security Analysis in PDF only on Docsity!

ERE (EXTRA REGIMENTAL

EMPLOYEES) 371 Exam 2 Standardized

2025 Questions With Full Answers

Upgraded A.

Traverse

Series of lines of known length connected at traverse stations, related by known angles. Stations must have visibility to next and previous station.

Traversing

Activity of establishing and measuring traverse. Applied as common method for local horizontal control surveys.

Mathematically Closed Traverse

  • Geometrically closed : polygon that begins and ends on same point. Checks: angular measurements
  • Geometrically open : begin/end on different points. point locations known better than measurements. Control station on both ends. Checks: angles and distances.

Mathematically open traverse

Begin and end on unrelated pts. Control station on only 1 end. No checks/ closure so must repeat measurements. Application: exploratory surveys

Interior angles

usually turn CW. Checks: measure exterior angle or (n-2)*

Deflection Angles

Measure L or R from prior direction. Used for geometrically open (e.g. route). Sight backsight and then turn angle to foresight.

Distance methods

Stadia, taping, EDM. Varies in accuracy/ time/ cost. Geo open = stationing, Geo closed = measure lines individually. Often EDM is used to meet standards.

Stationing

Identify key pts along route. Show distance from pt of beginning (POB)

"Full stations" use 100 ft / 1000 m increments and "Pluses" between full stations (i.e. POB: station 0+00, 1+11.2 = 111.2 feet along route from POB)

Hubs / Traverse Stations

location depends on purpose of survey - mapping vs. construction vs. property. Issue of accuracy, utility, & efficiency. Must be intervisible, and maximize line length. Permanent or relocatable.

Referencing traverse station

measured with different accuracy.

  • determine preliminary line directions
  • calc deps/lats
  • calc preliminary station coordinates
  • adjust measurements
  • calc adjusted station coordinates
  • calc adjusted lengths and directions of lines

Traverses can be open or closed, both mathematically and geometrically. Explain the

distinction between these types of traverses.

Mathematically closed traverses begin and end on points that are known. In the case of a

mathematically and geometrically closed traverse, the beginning and end points are the same; in the

case of a mathematically closed, but geometrically open traverse, the beginning and end points are

known relative to each other, but are not the same. A mathematically open traverse begins and ends

on points that have no known relationship; therefore, mathematically open traverses must also be

geometrically open since they end on a different point from where they began.

A route survey begins on station 100+00, then proceeds 159.60 ft to point A, and from

there 312.12 ft to point B. Compute the stationing for point A and point B.

Each full station is 100 feet counted along the route, thus point A is at station 101+59.60 and point B

is at station 104+71.72.

Describe an issue in selecting the location of traverse station. How might this issue vary

depending on the application of the control network under development?

Any reasonable answer is acceptable here; ideas discussed in class include accuracy, utility, efficiency,

intervisibility, and permanence. These issues might have slightly different resolution depending on

the type of survey that will subsequently be performed, e.g., mapping vs. construction vs. cadastral. If

a traverse is being performed to map a region, then the primary features need to be visible from at least

one traverse station; if the survey is for construction, issues with permanence in any area that is

undergoing change become critical; for cadastral surveys, the property corners much be visible from

one of the traverse points.

Describe the purpose of traverse computations. What are the underlying assumptions that

should be met before performing traverse adjustment?

Traverse computations are used to check if required accuracy is met, to adjust a traverse to get

geometric consistency and to compute control point locations. Performing traverse adjustment does

not make a traverse better or more accurate, just more consistent. Traverse adjustment should only be

applied when systematic errors and mistakes have been removed and the remaining random errors are

normally distributed and fall within the error tolerance that is appropriate for the survey application.

Three approaches to adjustment were discussed in class: arbitrary, compass rule, and least squares.

Traversing Errors/Mistakes

Personal error: poor station location related to line of sight. Angle/Distance measurement errors can be personal, instrumental, or Natural. Mistakes include set up of instrument/back/foresight, and notetaking

local horizontal i.e., it is perpendicular to gravity at a point and tangent to the geoid at a point.

However, the plane is not necessary tangent to the ellipsoid or the actual Earth surface. The use

of a plane for a reference surface is appropriate for small extents, particularly with lower

accuracy specifications.

Geoid

equipotential gravitational surface, i.e., it has equal gravitational potential at all

points. The geoid is perpendicular to gravity everywhere. Mean sea level is a common example

of a geoid. The geoid is mathematically undefined, but is observable and is commonly used for

vertical reference surfaces.

Ellipsoid

mathematical surface obtained by revolving an ellipse about polar axis. The

dimensions of the ellipse are typically selected to provide the closest fit to the geoid. The

ellipsoid is mathematically defined, and is commonly used for global, or continental, horizontal

reference surfaces.

Plane

defined using

local horizontal i.e., it is perpendicular to gravity at a point and tangent to the geoid at a point.

However, the plane is not necessary tangent to the ellipsoid or the actual Earth surface. The use

of a plane for a reference surface is appropriate for small extents, particularly with lower

accuracy specifications.

Describe a consequence of ignoring earth curvature when making measurements of horizontal

distance

the difference between a direct line connecting two points and the great

circle connecting two points is insignificant for relatively long distances i.e. only a 6mm

difference over 8 km. However, the discrepancy is more significant as distances become much

larger, e.g. over 1000km there is more than a 1 km difference between a straight line distance

and a great circle distance.

Describe a consequence of ignoring earth curvature when making measurements of vertical distance

the difference between a horizontal plane and a level surface is measurably

different at relatively short distances, e.g. at a mile out, the separation is approximately 8 inches.

Describe a consequence of ignoring earth curvature when making measurements of horizontal angles.

in a plane triangle, angles sum to 180°. This holds true for triangles of area

up to approximately 75 sq. miles, at which point because of earth curvature, the angle sum is

increased by one second.

Describe the Universal Transverse Mercator Coordinate system, including origin, projection

characteristics and coordinate components. What are the advantages and disadvantages of using

Explain why grid and geodetic azimuths at a point are typically not the same.

The UTM and State Plane coordinate systems select a central meridian for a zone, and then

create a rectangular grid with all grid meridians parallel to the central meridian. Along the

central meridian, grid and true azimuths will be the same, but as you move away from the central

meridian, the convergence of the true meridians toward the North Pole mean that the true north

meridian is not parallel to the grid meridian, thus directions relative to the two different systems

will not be the same.

Arbitrary adjustments

essentially distribute angular and distance error using no particular justification.

It would be hard to find any scenario where this would be justifiable.