Course Instructions

NOTE: The following pages contain a preview of the final exam. This final exam is identical to the final exam that you will take online after you purchase the course.

After you purchase the course online, you will be taken to a receipt page online which will have the following link: Click Here to Take Online Exam. You will then click on this link to take the final exam.

3 Easy Steps to Complete the Course:

1.) Read the Course PDF Below.

2.) Purchase the Course Online & Take the Final Exam – see note above

3.) Print Out Your Certificate

Construction Surveying – Earthwork : Final Exam

1. The cross section used in earthwork computations is a vertical section.

a. True

b. False

2. The determination of cross-section areas is ________ when the sections are plotted on

cross-section paper:

a. complicated.

b. not possible.

c. not reliable.

d. simplified.

3. Regarding Area Computation, the surveyor can determine cross-section areas for

construction earthwork volumes by one of the following methods: the counting squares

method, the geometric method (geometry of trapezoids and triangles), the __________, or the

double-meridian-distance method:

a. triangulation method.

b. exponential method.

c. stripper method.

d. perimeter method.

4. Which of the following is NOT an actual method of determining cross-section areas?

a. Counting-Squares Method.

b. Exponential Method.

c. Geometric Method.

d. Stripper Method.

5. When determining Area by Planimeter, the surveyor uses a ________ planimeter to

measure the area of a plotted figure.

a. polar.

b. radial.

c. parallel.

d. aerial.

6. According to Figure 4-6, the planimeter has and anchor arm and a tracing arm.

a. True

b. False

7. Regarding Procedures, one rule for using a planimeter is to always measure cut and

fill areas ___________:

a. together.

b. by interpolation.

c. with a protractor.

d. separately.

8. Regarding Procedures, a simple method of testing its consistency of operation is to

trace an area of 1 square inch with the arm set for a 1:1 ratio. The disk, drum, and vernier

combined should read 1.000 for this area.

a. True

b. False

9. Excavated material is usually classified as _____________, loose rock, and solid rock:

a. common excavation.

b. soil.

c. CA-6.

d. organic material.

10. Regarding Borrow Pits, when laying out the grid, the surveyor must lay out two

baselines parallel to two adjacent sides of the grid for use in reestablishing the grid.

a. True

b. False

CHAPTER 4EARTHWORK

Section I. PLANNING OF EARTHWORK OPERATIONS

IMPORTANCEIn road, railroad, and airfield construction,the movement of large volumes of earth(earthwork) is one of the most importantconstruction operations. It requires a greatamount of engineering effort.

The planning, scheduling, and supervisingof earthwork operations are of majorimportance in obtaining an efficientlyoperated construction project. TO plan aschedule, the quantities of clearing, grubbing,and stripping, as well as the quantities andpositions of cuts and fills, must be known.Then, the most efficient type and number ofpieces of earthmoving equipment can bechosen, the proper number of personnelassigned, and the appropriate time allotted.

Earthwork computations involve the cal-culation of volumes or quantities, the

determination of final grades, the balancingof cuts and fills, and the planning of the mosteconomical haul of material. The surveyoruses field notes and established grade to plotthe cross sections at regular stations and atany plus stations which may have beenestablished at critical intermediate points.The line representing the existing groundsurface and those lines representing theproposed cut or fill enclose cross-sectionareas. The surveyor uses these areas and themeasured distances along the centerline tocompute earthwork volumes.

CROSS SECTIONSThe cross section used in earthworkcomputations is a vertical section. It isperpendicular to the centerline at full andplus stations and represents the boundaries

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of a proposed or existing cut or fill. Typicalcross sections for a roadbed are illustrated infigure 4-1.

The determination of cross-section areas issimplified when the sections are plotted oncross-section paper. This is usually done tothe same vertical and horizontal scale,standard practice being 1 inch equals 10 feet.

However, if the vertical cut or fill is small incomparison with the width, the surveyor mayuse an exaggerated vertical scale to gainadditional precision in plotting such sections.

The surveyor must take care, however, whencomputing areas of this type of plotted sectionthat the proper area is obtained. For example,a 1 inch equals 10 foot scale, both vertical and

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horizontal, yields 100 square feet, but 1 inchequals 10 foot horizontal and 1 inch equals 2foot vertical yields only 20 square feet. Anexaggerated vertical scale is used in figure4-2 to illustrate a five-level section.

The side slopes of a cross section are expressedby a ratio of horizontal distance to verticaldistance. A 1 ½:1 side slope indicates a slopeextending 1 ½ feet horizontally per foot ofvertical rise or fall. Slopes may be inclined

more or less sharply than this, such as 3:1,2:1, or 1:1. The surveyor usually determinesthe slope by the design specifications basedon the stability of the soil in cut or fill.However, the need for economy in con-struction operations must often be considered.For example, cut slopes may be flattenedmore than is required by soil characteristicssolely to produce enough material for a nearbyfill. This practice is more economical thanoperating a borrow pit to obtain this material.

Section II. AREAS AREA COMPUTATIONThe surveyor can determnecross-sectionareas for construction earthwork volumes by approximate results, while the other methods

the-squares methods are simple and given

one of the following methods: the counting give results as accurate as the cross-sectionsquares method, the geometric method field data will permit. Standard practice(geometry of trapezoids and triangles), the requires that cut and fill areas of a crossstripper method, or the double-meridian- section, where both occur simultaneously, bedistance method. The stripper and counting- determined separately.

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Counting-Squares MethodTo make a hasty approximation of a cross-section area plotted on cross-section paper,count the number of squares enclosed by theboundary lines of the section. Then multiplythe total number of counted squares by thenumber of square feet represented by a singlesquare.For example, the cross section in figure 4-2encloses approximately 350 1/10-inch squaresor 3.5 l-inch squares. The scales of the crosssection indicate that one 1/l0-inch squarerepresents 1 foot horizontally and 6 inchesvertically, or one half of a square foot in area.Therefore, the approximate area of the crosssection is 350 divided by 2 equals 175 squarefeet. Using the l-inch square, which rep-resents 10 feet horizontally and 5 feetvertically or 50 square feet in area, the cross-section area is approximately 3.5 x 50 = 175square feet.

Geometric Method To compute the area of a cross section by thegeometric method, sometimes called thetrapezoidal method, subdivide the area intosimple geometrical figures, calculate eacharea according to its geometry, and total theresults. There is no set rule for performing thesubdivisions. The computer selects thosesubdivisions which will produce the mostdirect and accurate results. Figure 4-3aillustrates the subdivision of a typical three-level section into five triangles. Figure 4-3billustrates the subdivision of a five-levelsection into two triangles and two trapezoids.The following computations apply to thegeometric method in figure 4-2. Basic for-mulas are as follows.

A = area; b, bl, and b2 = the lengths of thebases; and h = the perpendicular distance, orheight, between parallel bases for a trapezoidand from base to vertex for a triangle.

square feet2A of triangle AJK = 5.7 x 4.0 = 22.82A of triangle ABJ = 5.2 (5.7+ 6.0) = 60.82A of trapezoid BCIJ = 9.3 (5.2+ 4.2) = 87.42A of trapezoid CDHI = 15.0 (4.2+ 4.7;= 133.52A of trapezoid DEGH = 4.8 (4.7+ 1.5)= 29.82A of triangle EFG = 1.5 x 4.5 = 6.8Total (double area of AFHK) = 341.1

Area of the cross section = 341.1 ÷2 = 170.5

Note that the computation is simplified byadding all the numerical products fortriangles and trapezoids together and thendividing the total by 2. The dashed line, AJ, isadded to subdivide quadrilateral ABJK intotwo triangles, AJK and ABJ.

Stripper Method To determine the area of a plotted crosssection by strip measurements, subdivide thearea into strips by vertical lines spaced atregular intervals. Measure the total length ofthese lines by cumulatively marking thelength of each line along the edge of astripper made of paper or plastic. Then,multiply the cumulative total of the averagebase lengths by the width of the strip. Regular

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intervals of 3, 5, or 10 feet, depending upon given to the horizontal and vertical scales ofthe roughness of the ground, give satisfactory the cross section. The procedure is illustratedresults for strip widths. Due regard must be in figure 4-4.

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The stripper shown is 5 squares wide by 60squares long. Its zero index is placed at theintersection of the ground and side-slope lineof the section.

The stripper is moved an interval of 5 squaresto the right with zero reading at the bottom. Itis then moved another 5 squares to the rightwith the previous top reading (2.5) nowadjacent to the bottom line. The stripper isagain moved 5 squares to the right for anotherinterval with the previous top reading (6.0)adjacent to the bottom line.

This process of moving 5 squares to the rightand bringing the top reading to the bottomline is continued until the stripper reachesthe right edge of the cross section with a finalreading of 53.0. Multiply this last reading(53.0) by the strip width used (5) to get thenumber of squares in the section (265.0). Tofind the area of the cross section in squarefeet, multiply the number of squares by thearea in square feet of one square.

Double-Meridian-Distance Method The double-meridian-distance (DMD) methodgives a more precise value for a cross-sectionarea than the stripper method. It does,however, involve more effort and time. It isessential that the elevations (latitudes) andthe distance from the centerline (departures)of all points on the cross section be known.

The method is based on the theory that thearea of a right triangle equals one half of theproduct of the two sides. Since latitudes anddepartures are at right angles to each other,the area bounded by the distance, the latitude,and the departure is a right angle. Thesurveyor can determine this area by takingone half of the product of the latitude and thedeparture. However, depending on its lo-cation, the triangle may add to or subtractfrom the total area of the irregular figure.

To avoid determining a plus or minus area foreach triangle, a slight refinement is made.The departure is added twice. It is first addedwhen determining the DMD of the course and

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second, when determining the next course’sDMD. Multiplying the DMD of each courseby its latitude results in twice the area, butthe sign of this product illustrates whetherthe area adds to or subtracts from the figurearea.

A step-by-step procedure to work out a DMDarea is given below and illustrated in figure4-5.

(1)

(2)

(3)

(4)

(5)

(6)

(7)

Compute anddepartures.

Select the far

record all the latitudes and

left station (D) as the firstpoint and D-E as the first course to avoidnegative areas in the DMD.

The DMD of the first course equals thedeparture of the course itself, 4.0.

The DMD of any other course (E-F) equalsthe DMD of the preceding course (D-E)plus the departure of the preceding course(D-E) and the departure of the course (E-F) itself or 4.0 + 4.0 + 30,0 = 38.0. For thenext course (F-I), the same procedure isfollowed. Add together the DMD of thepreceding course, the departure of thepreceding course, and the departure of thecourse itself, or 38.0 + 30.0 + 30.0 = 98.0.

The DMD of the last course is numericallyequal to its departure but with the oppositesign (+14.0).

Multiply each DMD value by its latitude.Positive products are entered under northdouble areas and negative products undersouth double areas.

The sum of all north double areas minusthe sum of all the south double areas,DISREGARDING THE SIGNS, equalstwice the cross-section areas. Divide thisdouble area by 2 to get the true cross-section area.

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AREA BY PLANIMETER The surveyor uses a polar planimeter tomeasure the area of a plotted figure. Thereare two types of planimeters. One has a fixedscale, and one has an adjustable scale.Basically, the surveyor uses both in the sameway, with the exception that the fixed scalecannot be adjusted to yield a 1:1 ratio whentracing areas.

OperationThe planimeter (figure 4-6) touches the paperat four points: the anchor point (B), thetracing point (A), the drum (C), and thesupport wheel (G). The adjustable tracingarm (E) is graduated to permit adjustment tothe scale of the plotted figure. This adjustmentprovides a direct ratio between the area tracedby the tracing point and the revolutions ofthe roller. The scale screws, Fl, F2, and F3,are used to accomplish the proper adjustmentof the tracing arm scale. Proper scale settingsare provided with each instrument. If thescale setting provided yields an area that istoo large, the scale reading must be increasedand vice versa.

As the planimeter encircles the area to bemeasured, the drum (C) revolves and recordsthe answer in tens and hundreds. A vernier(M) is mounted adjacent to the drum and

enables a single unit (ones) reading. The disk(D) is attached to the drum by a worm gear,counting the number of drum revolutionsand giving the thousands reading. Thesurveyor must first read the disk forthousands, then the drum for hundreds andtens, and finally, the vernier for single units(ones).

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ProceduresThe following are rules for using a planimeter,

Always measure cut and fill areasseparately.

Check the accuracy of the planimeter as ameasuring device to guard against errorsdue to temperature changes and othernoncompensating factors. A simplemethod of testing its consistency ofoperation is to trace an area of 1 squareinch with the arm set for a 1:1 ratio. Thedisk, drum, and vernier combined shouldread 1.000 for this area.

Before measuring a specific area,determine the scale of the plot and set theadjustable arm of the planimeter ac-cording to the chart in the planimetercase. Check the setting by carefullytracing a known area, such as five largesquares on the cross-section paper, andverifying the reading on the disk, drum,and vernier. If the reading is inconsistentwith the known area, readjust the armsettings until a satisfactory reading isobtained.

To measure an area, set the anchor pointof the adjusted planimeter at a convenient

position outside the plotted area; placethe tracing point on a selected point onthe perimeter of the cross section; take aninitial reading from the disk, drum, andvernier; continue tracing the perimeterclockwise, keeping the tracing pointcarefully on the line being followed; andwhen the tracing point closes on theinitial point, again take a reading fromthe disk, drum, and vernier. The differencebetween the initial reading and the finalreading gives a value proportional to thearea being traced.

Make two independent measurements ofthe area to insure accurate results. Makethe second measurement with the tracingpoint placed at a point on the oppositeside of the first measurement. Thisprocedure gives two compensatingreadings. The mean of these readings ismore accurate than either one in-dividually.

To measure plotted areas larger than thecapacity of the planimeter, divide theareas into sections and measure eachseparately.

Section III. EARTH AND ROCK EXCAVATION

CLASSES OF EXCAVATED MATERIAL

Excavated material is usually classified ascommon excavation, loose rock, and solidrock. Although classifying excavationmaterial is not a survey function, the surveyormust differentiate among the different typesso excavation records will match theconstruction work. When performing surveysto determine quantities of excavatedmaterials, the surveyor must record commonexcavation, loose-rock excavation, and solid-rock excavation data separately in the fieldnotes.

Common excavation involves the moving ofearth or of earth with detached boulders lessthan one-half cubic yard in volume. Loose-rock excavation involves the moving ofconsolidated materials which have beenloosened without blasting with picks, bars, orsimple air and mechanical devices. Solid-rock excavation involves the moving of rockfrom solid beds or the breaking up of bouldersmeasuring 1 cubic yard or more by means ofexplosives.

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BORROW PITSWhen there is an imbalance in the volume ofcuts and fills in construction projects, it isoften necessary to borrow the required filldirt from borrow pits outside the constructionlimits but near the fill site. Any time the hauldistance between the last available dirt andthe fill site becomes too far, it is cheaper toestablish a borrow pit.

Under some circumstances, it is not necessaryto survey borrow pits. However, it is oftennecessary to buy the fill dirt. The surveyormust determine how much earth was removedfrom the borrow pit. This can be done byestablishing a grid over the area to beexcavated. The grid can beat any convenientinterval (for example, 10-, 25-, 50-, or 100-footsquares).

Once the grid is staked, the surveyor candetermine the elevation of each grid cornerby leveling. The volume of earth that has

been removed can be computed at any timeby reestablishing the grid corners anddetermining their new elevation. Thesurveyor does this by subtracting the averageelevation of the grid corners after excavationfrom the average elevation of the same gridcorners before excavation and multiplyingthe difference by the number of square feet inthe grid square.

When laying out the grid, the surveyor mustlay out two baselines parallel to two adjacentsides of the grid for use in reestablishing thegrid. The surveyor should place them farenough outside the area of excavation toavoid destruction but close enough to beconvenient. (See figure 4-7.)

The surveyor should treat waste areas ordumps where excess material is deposited inthe same manner as borrow pits, with theexception that the volume to be measured isthe volume deposited, not excavated.

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