DEPARTMENT OF GEODETIC
ENGINEERING
Visca, Baybay City, Leyte, PHILIPPINES
Telephone: (053) 565-0600 local 1027
Email: dge@vsu.edu.ph
Website: www.vsu.edu.ph
ESci 121 – Fundamentals of Surveying
Exercise No. 3: Taping over Even and Uneven Ground Surfaces
I.
Name: JOH PAUL B. LORIAGA
Date Performed: 2/07/2024
Course and Year: BSCE-2
Date Submitted: 2/14/2024
Introduction
Measuring horizontal distances is one of the essential operations in surveying.
Of all the methods of measuring horizontal distances, taping is the most common and
usually done by surveyors in the absence of more advanced measuring instruments
with acceptable accuracy and precision. The taping process is accomplished with the
use of a calibrated tape. Therefore, the measurement process requires a well-trained
taping team and possesses the necessary skills to achieve acceptable and reliable
results.
Perhaps taping over a smooth and level ground is easier to perform than
measurement done in uneven and sloping ground surfaces. Taping performed on the
latter ground type is a challenging task for surveyors and tapemen. Due to the terrain
configuration and the weight of the tape itself, the taping operation is a method that
needs extra care and attention and is employed by the breaking-the-tape method. This
taping method is a standard practice to hold the tape horizontally above ground and
plumb at one or both ends when taping on sloping or uneven ground terrain surfaces
(La Putt, 2008). The measured short distances along the course of the intended
measurement are then added to accumulate the total length. Thus, in the absence of
more advanced equipment, skills in taping a sloping ground should be acquired to
achieve higher accuracy and precision.
II.
Learning Outcomes
1. To measure the horizontal length of the line using a measuring tape over an even
and level ground surface supported throughout its length;
2. To measure the horizontal length of a line using a measuring tape over an uneven
and sloping ground surface by the method of breaking tape; and
3. To acquire an acceptable relative precision of the measured horizontal length of a
line in surveying operations.
III.
Materials
Steel tape/measuring tape, chaining pins, range poles, pegs or hubs, chalk or marking
crayons, and plumb bob.
IV.
Procedure
A. Taping over an even or level ground surface
1. Two points approximately 100 to 200 meters long will be identified and designated on
a level or even ground as points A and B, marked with chaining pins, or with the use of
marking chalk/crayons for concrete pavements.
2. Position the range poles at the already identified points, A and B. The range poles at
each endpoint help ensure maintaining a straight line of sight during the measurement.
3. At the start of measurement, the rear tapeman positions himself at Point A or the point of
beginning carrying the terminal mark of the tape, the head tapeman holding the zero end
of the tape walks toward the direction of measurement (Point B).
4. A third range pole is positioned at the zero end of the tape (along the head tapeman) to
check the line of sight with the other two range poles at the ends (Points A and B). When
viewing at each end, the third range pole in between will not be seen, then the direction of
measurement is in a straight line.
5. Put a mark/chaining pin or mark with chalk at the zero mark (or the end of the tape) and
record your measurement, say the full tape length.
6. The head tapeman then pulls the tape towards the direction of Point B, and the rear
tapeman positions himself at the previously occupied point by the head tapeman. The
process is repeated, and measurement is recorded for the next full tape length.
7. Measure the last full tape length towards the end of the line at Point B. The remaining
partial length is also measured at Point B with the head tapeman pulls the tape taut and
record correspondingly the fractional measurement read from the tape end.
8. After completing the measurement from Point A to Point B, do the same process in the
opposite direction, Point B to Point A. The mean of the two measures is taken as the
most probable value (MPV) of the length of the line.
9. Tabulate the observed and computed values using Table 1.
Table 1. Measured horizontal distances of an even or level ground by taping
Trial
1
2
Line
AB
BA
Length
Discrepancy
Mean
Relative Precision
Computations:
a. The discrepancy for the measurement is the absolute value difference between the two
measurements (AB and BA).
Discrepancy = |Length AB − Length BA|
b. The mean length of the measured line is the average value of the two measurements
and is the most probable value or MPV.
Mean Length = MPV =
Measured Length AB + Measured Length BA
2
c. The relative precision of the measurement is determined by dividing the discrepancy by
the mean length, where the numerator is reduced to unity or 1. The relative precision is
expressed in fractional form and the denominator is rounded to the nearest hundredth.
Discrepancy
Relative Precision =
Mean Length
d. The acceptable precision should be at least 1/1,000. If this is not attained the
measurement should be repeated.
B. Taping over an uneven and sloping ground surface
B.1 Measuring Uphill (C to D)
1. Two points approximately 100 to 200 meters long will be identified and designated on a
sloping or uneven ground as Point C (Downhill) and Point D (Uphill), marked with
chaining pins, or with the use of marking chalk/crayons for concrete pavements.
2. Position two ranges poles at both points (C and D) and measure the horizontal distance
employing the breaking-the-tape method.
3. The head tapeman pulls the zero mark of the tape uphill towards Point D, leaving the
other end positioned and fixed at Point C with the rear tapeman. At the head tapeman,
another range pole is placed at the zero-meter mark end of the tape to ensure a straight line
path along the course CD. When viewed from either Point (C or D), the intermediate rangepole should not be seen.
4. The rear tapeman raises the terminal mark of the tape (say the 30-meter or 50-meter
mark) breast-high while the head tapeman positions the zero-meter mark end of the
tape on the ground surface as high as the other raised end of the tape. Another member of
the team/group stays by the side of the line measured and ensures that the tape is held
horizontal and the three range poles (at Point C, D, and the intermediate point) in
alignment.
5. With the tape held horizontal and the alignment attained, the rear tapeman plumbs from
Point C to the terminal mark of the tape with a plumb bob and maintains this plumb bob
steady over Point C while the head tapeman pulls the tape taut.
6. Record the measurement and mark the points on the ground by chaining pins or
marking chalk/crayons.
7. The head tapeman advances uphill towards Point D, and the rear tapeman leaves his
end of the tape, moves up the slope, and gets hold of the tape at the point previously
held by the head tapeman. The subsequent measurement is made horizontally from the pin
stuck in the ground or the marked point with chalk/crayons by the head tapeman, and
the whole process is repeated until Point D is reached.
8. The horizontal length of line CD is the sum of the short measurements using the
breaking-the-tape method (Figure 1).
Figure 1. An illustration of the breaking-the-tape method in downhill measurement
B.2 Measuring Downhill (D to C)
1. The measurement downhill starts at Point D with the rear tapeman holding the
terminal meter mark of the tape. The tape is reversed with the head tapeman
holding the zero end and moving forward down the slope in the direction of Point C.
2. The head tapeman holds the plumb bob and align it with the range pole positioned in
between Points D and C where the first horizontal distance will be measured.
3. With the plumb bob dropped on the ground, indicate a mark using chalk/crayons
and proceed to reading the horizontal distance when the tape is already held
horizontal and the range poles alignment is attained. Record the measurement.
4. The head tapeman then advances downward in the direction of Point C while the
rear tapeman positions himself at the previously occupied point by the head
tapeman. Repeat the process of measurement until Point C is reached.
5. The horizontal length of line DC is the total of the short measurements using the
breaking-the-tape method (Figure 1).
6. Tabulate observed and computed values accordingly using Table 2.
Table 2. Measured horizontal distances of an uneven or sloping ground by taping
Trial
Line
Length
Difference
Mean
Relative Precision
1
CD
2
DC
Computations:
a. The discrepancy for the measurement is the absolute value difference between the two
measurements (CD and DC).
Discrepancy = |Length CD − Length DC|
b. The mean length of the measured line is the average value of the two measurements
and is the most probable value or MPV.
Mean Length = MPV =
Measured Length CD + Measured Length DC
2
c. The relative precision of the measurement is determined by dividing the discrepancy
by the mean length, where the numerator is reduced to unity or 1. The relative
precision is expressed in fractional form and the denominator is rounded to the
nearest hundredth.
Discrepancy
Relative Precision =
Mean Length
d. The acceptable precision should be at least 1/1,000. If this is not
attained the measurement should be repeated.
Guide Questions:
1.What are the common sources of errors in taping using the breaking tape method and
how would you lessen if not eliminate these errors?
Ans. The common sources of errors in taping using breaking tape method are human
error, the distance of breaking the tape, technique in handling the instruments and lastly,
the presence of wind and other natural phenomena. This sources of errors could be lessen
through minimizing the human error by careful and well execution of the reading and
measurement. The shorter the break, the less error can be committed because linearity of
the range poles can be assured. Proper technique and execution of the instruments can
also lessen the errors. Lastly, stiff and firm holding of the tape can solve the sagging and
wind problem.
2.How would you eliminate the effect of sag in taping a sloping ground?
Ans. The effect of sagging in taping a sloping ground can be eliminated and minimized
through firmly and stiffly holding the tape and shortening the distance of the break, because
in this way there is a lesser or no sag on the tape.
V.
Results and Discussion
A. Taping over an even or level ground surface
Table 1. Measured horizontal distances of an even or level ground by taping
Trial
1
2
Line
AB
BA
Length
100.93 m
100.94 m
Discrepancy
0.01
Mean
100.935 m
Relative Precision
1/1000
A to B
Measurement
Distance
1
40.00 m
2
30.00 m
3
30.93 m
Total
100.93 m
B to A
Measurement
1
2
3
Total
Table
Distance
29.00 m
30.00 m
45.97 m
100.94 m
1
shows
the
data
gathered
while
performing
Procedure 1. The length was measured with the aid of measuring tape and
range pools from point A to B and vice versa. The discrepancy is the
absolute difference of the two measured length. The mean length was
determined by adding the two measured length and dividing the sum by 2.
While the Relative precision is the quotient of the discrepancy and mean
length reduced to unity. As we can see, the result is accurate as the
Relative precision is in the acceptable range.
B.
Taping over an uneven or sloping ground surface
Table 2. Measured horizontal distances of an uneven or sloping ground by taping
Trial
Line
Length
Difference
Mean
Relative Precision
1
CD
104.07
0.72
103.71 m
1/144
2
DC
103.35
Uphill (C to D)
Measurement
1+2
3+4
5+6
7+8
9+10
11+12
13+14
15+16
Total
Distance
11 m
12 m
12 m
12 m
12 m
13.45 m
15.92 m
15.7 m
104.07
Downhill (D to C)
Measurement
1+2
3+4
5+6
7+8
9+10
11+12
15
Total
Distance
16 m
14.86 m
14 m
14 m
14 m
14 m
5.05 m
103.35
Table 2 shows the data gathered while performing Procedure B. The
lengths CD and DC was the actual measurements of the two points using
the technique of pacing. The discrepancy is the difference of the two
measurements. The Mean length was determined by adding the two
measurements and dividing
by 2. Lastly, the Relative precision was
determined by dividing the discrepancy by the mean length and reducing it
to unity. The result was quite inaccurate as the resulted RP was not in the
acceptable range. This inaccuracy was due to the errors committed while
conducting the activity. A lot of factors can contribute to the errors
committed, first, the wind pressure that may cause the tape to be unstable.
Also, skills of the students in handling the instruments greatly affected the
outcome of the activity.
Conclusion and Recommendations
VI.
All measurements in plane surveying are taken to be horizontal. This can be
achieved using the tape held horizontally in a sloping or uneven ground and held on
the ground in a level ground. Measuring the distance by taping along the along a
level and sloping ground is better if breaking tape method is applied. In this way,
linearity could be assured and angular displacement that may cause error could be
minimized.
Errors always happened in every field work but as long as you aware of it,
you can take it in considerations. In measuring distance, always keep it in a straight
path. Keeping the line of measurement straight requires both rear tapeman and pole
man’s attention especially if the when the tape is being held in a certain level due to
sloping ground. Plumb bob is used to keep the path straight to the direction of the
pole on the end of the path. Errors will occur if the tape is not leveled or not pulled
properly or is sag. Properly mark where the tip of the plumb bob points to assure
accuracy and less errors. Accuracy in taping measurement can also be assured by
minimizing the human error, and proper reading reading of measurement. Be patient
in conducting the activity and enjoy.
VII.
References
Remulla, (2019). Taping on level and uneven ground. https://pdfcoffee.com/field-work-2copydocx-pdf-free.html