ce3500 exam two

what are the three main parts of an engineer’s transit

1. upper plate or alidade assembly

2. leveling head assembly

3. lower plate assembly

degree

defined by dividing one complete rotation into 360 equal parts

radians

defines an angle using the relationship between the arc length and the radius of a circle

what are the three main parts of a total station

1. electronic distance measuring (EDM) instrument

2. an electronic angle measuring component

3. a computer or microprocessor

what is a total station used for

observing horizontal and vertical angles, and slope distances from a single setup

functions of total station

1. averages repeated measurements

2. corrects measurements for prism constant and atmospheric conditions (temp and pressure)

3. applies curvature and refraction corrections when appropriate

4. converts slope distance into horizontal and vertical components

5. computes points elevations using vertical angle distance measurements

6. computes points coordinates from measured angles and distances

how to set up total station over a point

1. tripod legs should be equally spaced

2. tripod head should be approximately level

3. head should be directly over the point. use the centering screw for sighting the point on the ground

what are horizontal angles usually measured with

a theodolite or total station

for all closed polygons of n sides, the sum of the interior angles will be…

(n - 2)(180 degrees)

for all closed polygons of n sides, the sum of the exterior angles will be…

(n + 2)(180 degrees)

traverse can be solved by…

• interior angles

• exterior angles

• deflection angles

a surveyor’s compass uses a ___ to measure __ (bearings or azimuths)

magnetic needle, magnetic directions

what is used for measuring horizontal and vertical angles or directions and extending straight lines

angles, bearing, and azimuth measurements

what are the two traditional instruments that used to be used for angles, bearing, and azimuth measurements

the engineer’s transit and the theodolite

azimuth

the direction of a line as given by an angle measured clockwise (usually) from the north end of a meridian

bearing

the direction of a line as given by the angle between the line and a meridian

how can a bearing angle be measured

CW or CCW from the north or south end of the meridian

NE bearing=

azimuth

SE bearing=

180 degrees - azimuth

SW bearing

azimuth - 180 degrees

NW bearing=

360 degrees - azimuth

traversing

a rapid convenient method for establishing or extending horizontal control points

what are the main purposes of traverses

• property surveys to locate and establish boundaries

• supplementary horizontal control for topographic mapping surveys

• location and construction layout surveys for highways, railways, and other private or public works

control points

reference points of known geospatial coordinates. it may consist of any known point capable of establishing accurate control of distance and direction (ex: coordinates, elevation, bearings)

what are the advantages of traversing

1. less reconnaissance and organization

2. are not subject to the strength-of-figure requirements of triangulation networks

3. scale errors do not accumulate throughout the traverse

where do open traverses start and end

they start at a point of known position and end at a point of unknown position

open traverses are…

very risky and should be avoided

open traverse checks

no computational checks are therefore possible to detect any errors or blunders in distances or direction

where do closed traverses start and end

they start and end on points of known position

closed traverse checks

since the start and ends points are known, this provides a computational check on the measurements and calculations

systematic errors and blunders in closed traverses can..

be detected in both the distance and direction

to provide known positions for the start and end points in closed traverses…

at least one known bearing or azimuth is also needed

in closed traverses, more than one bearing is required to…

prevent the entire traverse from pivoting about a single known point

errors and blunders in angles and distances can be detected through…

angular and coordinate closure checks

in closed traverses, one known bearing/azimuth…

orients the traverse

in closed traverses, additional known bearing/azimuth…

checks the orientation and angular closure

permissible misclosure

c = k*sqrt(n)

where: k is the traverse order accuracy

n is the number of angles

traverse adjustment steps

• adjust interior angles using (n-2)*180

• compute all azimuths

• adjustment of coordinates

  • linear methods

    • bowditch compass rule

    • transit rule

  • non-linear methods

    • least squares

departure

represents the horizontal distance in the east-west direction

latitude

represents the vertical distance perpendicular to departure and along the north-south direction

regularly spaced offsets

well known rule for area calculation

• trapezoid

• simpson

irregularly spaced offsets

area by coordinates; shoelace formula

what are the three methods used to calculate volumes

1. cross-section method

2. unit-area or borrow-pit method

3. contour-area method

flat topography cross-section

ordinary topography cross-section

required for rough topography cross-section

practical for rough topography cross-section

from cut to fill cross-section

side-hill locations cross-section

traverse ties

requires at least two fixed objects

total station

modernization of theodolite

traverse linear misclosure

difference btwn measured and actual point

engineer’s transit

vernier-reading

centering

optical plummet

traverse network adjustment

least squares method

traverse angle adjustment

balancing

traverse angle measurement

clockwise and counterclockwise

bearing

surveyor’s compassco

coordinates

indirect measurements

the interior angles summation of an 8-angle closed traverse network is

1080 degrees

total station reduce slope distances to __ and __ components

horizontal and vertical

which quadrant has azimuth equal to bearing

the first quadrant (NE)

t/f: the accuracy of the closed traverse relies on balancing the departure and latitude

true

t/f: total station applies various corrections to the observed distances

true

t/f: the total station’s maximum accuracy is 10 times higher than the engineer’s transit

false

t/f: angle between intersecting lines can be calculated by subtracting their azimuths

true

t/f: open and closed traverses should be avoided

false

t/f: the azimuth angle is measured clockwise or counterclockwise

false