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2/11/2014
Surveying
Dr. Madhar M. Taamneh
Civil Engineering Department
Yarmouk University
Summer - 2013
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Part I • Units and Significant Figures
 2.1 Introduction
Five
ve types of
o observations
obse vat o s
illustrated in Figure 2.1
form the basis of
traditional plane
surveying:
1.
2.
3.
4.
5.
horizontal angles,
horizontal distances,
vertical (or zenith) angles,
vertical distances, and
slope distances
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 2.1 Introduction
 In the figure, OAB and ECD
are horizontal planes, and
OACE and ABDC are vertical
planes.
 Horizontal angles
angles, such as angle
AOB, and horizontal distances,
OA and OB, are measured in
horizontal planes;
 Vertical angles, such as AOC,
are measured in vertical planes;
 Zenith angles, such as EOC, are
also measured in vertical
planes;
 Vertical lines, such as AC and
BD, are measured vertically (in
the direction of gravity); and
 Slope distances, such as OC, are
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determined along inclined
planes.
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 2.2 Units of Measurement
 In surveying, the most commonly employed units
are length, area, volume, and angle.
 Two different systems are in use for specifying
units of observed quantities;
English system
Metric system (International System of Units,
and abbreviated SI)
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 2.2 Units of Measurement
 Unit of Length
 Foot in the English system
 Meter in the metric system.
system
 In the past, two different definitions have been used to
relate the foot and meter.
 In 1893, the United States officially adopted a standard in
which 39.37 in. was exactly equivalent to 1 m. Under this
standard, the foot was approximately equal to 0.3048006 m.
(U.S. survey foot)
 In1959, a new standard was officially adopted in which the
inch was equal to exactly 2.54 cm. Under this standard, 1 ft
equals exactly 0.3048 m. (International foot)
 Differs from the previous one by about 1 part in 500,000, or
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approximately 1 foot per 100 miles.
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 2.2 Units of Measurement
 The National Geodetic Survey uses the meter in its
distance measurements.
 English system has long been the officially adopted
standard for measurements in the United States, except
for geodetic surveys. Therefore;
 The linear units of feet and decimals of a foot are most
commonly used by surveyors
 In construction feet and inches are often used.
 Surveyors must understand all the various systems of units
and be capable of making conversions between them.
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 2.2 Units of Measurement
 A summary of the length units used in past and present
surveys in the United States includes the following:
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 2.2 Units of Measurement
Unit of Area
 In the English system,
system areas are given in square feet or
square yards.
 The most common unit for large areas is the acre.
 Ten square chains (Gunter’s) equal 1 acre.
 Thus an acre contains 43,560 ft2, which is the product of
10 and 662.
 The arpent (equal to approximately 0.85 acre, but varying
somewhat in different states) was used in land grants of
the French crown.
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2.2 Units of Measurement
 Unit of Volume
 Volumes in the English system can be given in cubic
feet or cubic yards.
 For very large volumes, for example, the quantity of
water in a reservoir, the acre-foot unit is used. It is
equivalent to the area of an acre having a depth of 1 ft,
,
ft3.
and thus is 43,560
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 2.2 Units of Measurement
 Unit of Angle
 The unit of angle used in surveying is the degree
degree,
defined as 1/360 of a circle.
 One degree (1°) equals 60 min, and 1 min equals 60
sec.
 Divisions of seconds are given in tenths, hundredths,
and thousandths.
thousandths
 A radian is the angle subtended by an arc of a circle
having a length equal to the radius of the circle.
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 2.3 International System of Units (SI)
 Unit of length
 meter is the basic unit
 Unit of Area
 Square meter (m2).
 Large areas are given in hectares (ha), where one hectare is
equivalent to a square having sides of 100 m. Thus, there are 10,000
m2, or about 2.471 acres per hectare.
 Unit of Volume
 The cubic meter (m3) is used for volumes in the SI system.
system
 Unit of Angles
 Degrees, minutes, and seconds, or the radian, are accepted SI units
for angles.
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 2.4 Significant Figures
 Significant figures (number of digits) is an indication
of the accuracy attained in measurements.
 By definition, the number of significant figures in any
observed value includes the positive (certain) digits
plus one (only one) digit that is estimated or rounded
off, and therefore questionable.
 For example, a distance measured with a tape whose
smallest graduation is 0.01 ft, and recorded as 73.52 ft,
is said to have four significant figures; in this case the
first three digits are certain, and the last is rounded off
and therefore questionable but still significant.
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 2.4 Significant Figures
 Some Examples:
 Two significant figures: 24, 2.4, 0.24, 0.0024, 0.020
 Three significant figures: 364, 36.4, 0.000364, 0.0240
 Four significant figures: 7621, 76.21, 0.0007621, 24.00.
 Zeros at the end of an integer value may cause difficulty
because they may or may not be significant. The preferred
method of eliminating this uncertainty is to express the value
in terms of powers of 10.
 For example, the observed value of 2400 may has two, three, or four
significant figures.

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2.400 * 103

2.40 * 103

2.4 * 103
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 2.4 Significant Figures
 The following three steps
will be followed for addition
or subtraction:
 (1) Identify the column
containing the rightmost
significant digit in each
number being added or
subtracted,
 (2) Perform the addition or
subtraction,, and
 (3) Round the answer so that
its rightmost significant digit
occurs in the leftmost column
identified in step (1).
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 2.4 Significant Figures
 In multiplication, the number of significant figures in
the answer is equal to the least number of significant
fi
figures
in
i any off the
h factors.
f
 For example
 362.56 * 2.13 = 772.2528 when multiplied, but the answer is
correctly given as 772.
 Likewise, in division the quotient should be rounded
off to contain only as many significant figures as the
least number of significant figures in either the divisor
or the dividend.
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 2.5 Rounding off Numbers
 Rounding off a number is the process of dropping one or
more digits so the answer contains only those digits that are
significant
significant.
 When the digit to be dropped is lower than 5, the number is
written without the digit. Thus, 78.374 becomes 78.37. Also
78.3749 rounded to four figures becomes 78.37.
 When the digit to be dropped is exactly 5, the nearest even
number is used for the preceding digit. Thus, 78.375 becomes
78.38 and 78.385 is also rounded to 78.38.
 When the digit to be dropped is greater than 5, the number is
written with the preceding digit increased by 1. Thus, 78.386
becomes 78.39.
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Part II • Field Notes
 2.6 Field Notes
 The only permanent records of work done in the field
field.
 They typically contain measurements, sketches,
descriptions, and many other items of miscellaneous
information.
 Two types of Filed Notes
 Hand
d lettering
l
i in
i field
fi ld books
b k or special
i l note pads.
d
 Automatic data collectors (electronic field book and
survey controllers).
 Can interface with many different modern surveying instruments.
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2.6 Field Notes
 If the data are incomplete, incorrect, lost, or destroyed,
much or all of the time and money invested in making
the measurements and records have been wasted.
 Hence, the job of data recording is frequently the most
important and difficult one in a surveying party.
 Recorded field data are used in the office to perform
computations, make drawings, or both.
 Property surveys are subject to court review under
some conditions, so field notes become an important
factor in litigation.
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2.7 General Requirements of Handwritten Field Notes
Accuracy
 This is the most important quality in all surveying
operations
Integrity
 A single omitted measurement or detail can nullify use of
the notes for computing or plotting.
 Notes
N t should
h ld be
b checked
h k d carefully
f ll for
f completeness
l t
before leaving the survey site.
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2.7 General Requirements of Handwritten Field
Notes
Legibility.
 Notes can be used only if they are legible.
legible
Arrangement.
 Note forms appropriate to a particular survey contribute
to accuracy, integrity, and legibility.
Clarity.
 Advance planning and proper field procedures are
necessary to ensure clarity of sketches and tabulations,
and to minimize the possibility of mistakes and
omissions
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Handwritten Field Notes
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2.8 Types of Field Books
 Since field books contain valuable data, suffer hard wear, and
must be permanent in nature, only the best should be used for
practical
ti l work.
k
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2.9 Kinds of Notes
 Four types of notes
are kept in practice:
1.
Sketches,
2.
Tabulations,
3.
Descriptions, and
4.
Combinations of
these.
When in doubt about the need for any information, include it and make a
sketch. It is better to have too much data than not enough.
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2. 12 Introduction to Automatic Data Collectors
 Advances in computer
technology
gy in recent yyears have
led to the development of
sophisticated automatic data
collection systems for taking
field notes.
Figure 2.4 Various data collectors that are used in the
field: (a) Trimble TSC2 data collector (Courtesy of
Trimble) and(b) Carlson Explorer data collector.
 Data collectors can be
interfaced with modern
surveying
y g instruments,, and
when operated in that mode
they can automatically receive
and store data in computer
compatible files as observations
are taken.
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2. 12 Introduction to Automatic Data Collectors
 Control of the measurement and storage operations is
maintained through the data collector’s keyboard.
 For clarification of the notes, the operator inputs point
identifiers and other descriptive information along
with the measurements as they are being recorded
automatically.
 When a job is completed or at day’s end, the files can
be transferred directly to a computer for further
processing.
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2. 12 Introduction to Automatic Data Collectors
 In using automatic data
collectors, the usual preliminary
p y
information such as date, party,
weather, time, and instrument
number is entered manually into
the file through the keyboard.
 For a given type of survey, the
data collector’s internal
microprocessor is programmed
to follow a specific sequence of
steps.
 The
h operator identifies
id ifi the
h type
of survey to be performed from
a menu, or by means of a code,
and then follows instructions
that appear on the unit’s screen.
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2. 12 Introduction to Automatic Data Collectors
 Step-by-step prompts
will guide the operator
to either
ih
 (a) input “external”
data (which may
include station names,
descriptions, or other
information) or
 (b) press a key
k to
initiate the automatic
recording of observed
values.
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2. 12 Introduction to Automatic Data Collectors
 Many
a y instrument
st u e t
manufacturers incorporate
data collection systems as
internal components
directly into their
equipment. This
incorporates all features of
external data collectors,
including the display
panel, within the
instrument.
Figure 2.5 The Topcon GTS 800 total
station with internal data collector.
(Courtesy Topcon Positioning Systems.)
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2. 13 Transfer of Files from Data Collectors
 At regular intervals, usually at
lunchtime and at the end of a
day’s work, or when a survey
h been
has
b
completed,
l t d the
th
information stored in files
within a data collector is
transferred to another device.
 This is a safety precaution to
avoid accidentally losing
substantial amounts of data.
 Ultimately, of course, the files
are downloaded to a host
computer, which will perform
computations or generate maps
and plots from the data.
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2. 13 Transfer of Files from Data Collectors
 In one method that is particularly
convenient when surveying in
remote locations,, data can be
returned to the home office via
telephone technology using devices
called data modems.
 Another method of data transfer
consists in downloading data
straight into a computer by direct
hookup via an RS-232 cable.
 Data can be transferred to the office
using wireless connections
 Some surveying instruments, for
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example, the Topcon GTS 800
Series total station shown in Figure
2.5, are capable of storing data
externally on PCMCIA cards.
2. 14 Digital Data File Management
 Typical information downloaded from a data collector
includes:
 The computed coordinates file, and
 The raw data file.
 Many methods can be used to provide backup of digital
data
 It is wise to keep two copies of the files for all jobs
 Compact disk (CD) and digital video disk (DVD)
 Care must be taken in their handling and storage
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2. 15 Advantages and Disadvantages of Data Collectors
 Advantages
 Mistakes in reading and manually recording observations
i the
in
h field
fi ld are precluded.
l d d
 The time to process, display, and archive the field notes in
the office is reduced significantly.
 Systems that incorporate computers can execute some
programs in the field, which adds a significant advantage.
 Recorded
R
d d llarge quantities
i i off information
i f
i (Topographic
(T
hi
Surveys)
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2. 15 Advantages and Disadvantages of Data Collectors
 Disadvantages
 There is the slight chance, for example, the files could be
accidentally erased through carelessness or lost because of
malfunction or damage to the unit.
 Some difficulties are also created by the fact that sketches
cannot be entered into the computer.
 However, this problem can be overcome by
supplementing files with sketches made simultaneously
with the observations that include field codes
 These field codes can instruct the drafting software to
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draw a map of the data complete with lines, curves, and
mapping symbols.
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