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    • Abstract: UNESCO-NIGERIA TECHNICAL &VOCATIONAL EDUCATIONREVITALISATION PROJECT-PHASE IINATIONAL DIPLOMA INBUILDING TECHNOLOGYBASIC PRINCIPLES IN SURVEYING ICOURSE CODE: SUG 101YEAR I- SE MESTER I

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UNESCO-NIGERIA TECHNICAL &
VOCATIONAL EDUCATION
REVITALISATION PROJECT-PHASE II
NATIONAL DIPLOMA IN
BUILDING TECHNOLOGY
BASIC PRINCIPLES IN SURVEYING I
COURSE CODE: SUG 101
YEAR I- SE MESTER I
THEORY/PRACTICALS
Version 1: December 2008
1
TABLE OF CONTENTS
WEEK ONE:
• INTRODUCTION
• CLASSIFICATION OF SURVEYORS
• BRANCHES OF SURVEYING
WEEK TWO
• BASIC PRINCIPLES IN SURVEYING
• ERRORS IN SURVEYING
WEEK THREE
• EFFECTS OF ERRORS IN LINEAR MEASUREMENT
• CORRECTIONS OF ERRORS IN LINEAR MEASUREMENT
• STANDARDIZATION
• SLOPE CORRECTION
• SAG CORRECTION
• TEMPERATURE VARIATION
• TENSION CORRECTION
WEEK FOUR
• CHAIN SURVEYING
• EQUIPMENTS USED IN CHAIN SURVEYING
• NECESSARY PRECAUTIONS IN USING CHAIN SURVEYING
INSTRUMENTS
• GENERAL PROCEDURE IN MAKING A CHAIN SURVEY
• CRITERIA FOR SELECTING A SURVEY LINES/OFFSETS
WEEK FIVE
• METHOD OF MAKING LINEAR MEASUREMENTS IN SURVEYING
• METHOD OF SETTING OFFSET TO THE CHAIN LINE
• CHECK OR PROOF LINES
2
• FIELD NOTES
• METHOD OF PLOTTING THE SURVEY
WEEK SIX
• FIELD PROBLEMS (OBSTACLES) IN CHAIN SURVEYING
• WAYS OF OVERCOMING THEM
• ERRORS IN CHAIN SURVEYING
WEEK SEVEN
• LEVELLING
• SURVEYOR’S LEVELLING INSTRUMENTS
• LINE OF COLLIMATION
WEEK EIGHT
• CRITERIA FOR SELECTING LEVELLING DATUM
• CONSTRUCTION AND USE OF BENCH MARKS
• PROCEDURE IN LEVELING
WEEK NINE
• USES OF LEVELLING
• CONTOUR CHARACTERISTICS
• USES OF CONTOUR MAPS
• SOURCES OF ERROR IN LEVELLING
WEEK TEN
• THEODOLITES
• UNITS OF ANGULAR MEASUREMENT
• BASIC COMPONENTS OF AN OPTICAL THEODOLITE
WEEK ELEVEN
• COMPASS SURVEYING
• THE PRISMATIC COMPASS
• VARIATION IN DECLINATION
3
WEEK TWELVE
• INTERPRETATION OF MAPS, LAYOUT AND ENGINEERING SURVEY
PLAN
• TYPES OF MAPS
• GENERAL REQUIREMENT OF A MAP OR PLAN
• MAP SCALES
• PRINCIPLES OF PLAN PRODUCTION
WEEK THIRTEEN
• MEASURING DISTANCE FROM MAP OR PLAN
• MEASURING AREAS FROM THE SURVEY PLOT (MAP OR PLAN)
• MEASURING AREA BY THE PLANIMETER
• PLAN DISTORTION
WEEK FOURTEEN
• THE NATIONAL GRID
WEEK FIFTEEN
• SUBMISSION OF SURVEY RECORDS
• PRESERVATION OF SURVEY RECORDS
4
WEEK ONE:
INTRODUCTION
• Surveying is defined as “taking a general view of, by observation and
measurement determining the boundaries, size, position, quantity, condition,
value etc. of land, estates, building, farms mines etc. and finally presenting the
survey data in a suitable form”. This covers the work of the valuation surveyor,
the quantity surveyor, the building surveyor, the mining surveyor and so forth,
as well as the land surveyor.
• Another school of thought define surveying “as the act of making
measurement of the relative position of natural and man made features on
earth’s surface and the presentation of this information either graphically or
numerically.
The process of surveying is therefore in three stages namely:
(i) Taking a general view
This part of the definition is important as it indicates the need to obtain an
overall picture of what is required before any type of survey work is
undertaken. In land surveying, this is achieved during the reconnaissance
study.
(ii) Observation and Measurement
This part of the definition denotes the next stage of any survey, which in land
surveying constitutes the measurement to determine the relative position and
sizes of natural and artificial features on the land.
(iii) Presentation of Data:
The data collected in any survey must be presented in a form which allows the
information to be clearly interpreted and understood by others. This
presentation may take the form of written report, bills of quantities, datasheets,
drawings and in land surveying maps and plan showing the features on the
land.
5
CLASSIFICATION OF SURVEYORS
Surveying is made up of various specializations known as sectors or classes as
shown below:
1. General Practice Surveyors:
• Surveyors under this class are mostly concerned with valuation and
investment. Valuation surveyors deal with property markets, land and property
values, valuation procedures and property law. Investment surveyors help
investors to get the best possible return form property.
• They handle a selection of properties for purchase or sale by pension funds,
insurance companies, charities and other major investors. They also specialize
in housing policy advice, housing development and management.
2. Planning and Development Surveyors
• They are concerned with preparing planning applications and negotiating with
local authorities planners to obtain planning permission.
3. Building Surveyors
• Their work involves advising on the construction, maintenance, repair and
refurbishment of all types of residential and commercial property.
• The analysis of building defects is an important part of a building surveyors
discipline.
4. The Quantity Surveyors
• They evaluate project cost and advice on alternative proposals. They also
6
ensure that each element of a project agrees with the cost plan allowance and
that the overall project remains within budget.
5. Rural Practice Surveyors:
• Surveyors in rural practice advice land owners, farmers and others with
interests in the country side.
• They are responsible for the management of country estates and farms, the
planning and execution of development schemes for agriculture, forestation,
recreation, sales of properties and live stock.
6. Mineral Surveyors
• They plan the development and future of mineral workings. They work with
local authorities and the land owners on planning applications and appeals,
mining laws and working rights, mining subsidence and damage, the
environmental effects of land and rehabilitation of derelict land and deep
underground mines.
7. Land surveyors:
• They measure land and its physical features accurately and record them in the
form of a map or plan for the purpose of planning new building and by local
authorities in managing roads, housing estates, and other facilities.
• They also undertake the positioning and monitoring for construction works.
7
BRANCHES OF SURVEYING
Surveying
Aerial Land Hydrographic
Surveying Surveying Surveying
Geodetic Plane
Surveying Surveying
Cadastral Topographi Engineerin
Surveying c g
Surveying Surveying
1. Aerial Surveying
• Aerial surveys are undertaken by using photographs taken with special
cameras mounted in an aircraft viewed in pairs. The photographs produce
three-dimensional images of ground features from which maps or numerical
data can be produced usually with the aid of stereo plotting machines and
computers.
8
2. Hydrographic Surveying (Hydro-Survey)
• Hydro survey is undertaken to gather information in the marine environment
such as mapping out the coast lines and sea bed in order to produce
navigational charts.
9
• It is also used for off shore oil exploration and production, design, construction
and maintenance of harbours, inland water routes, river and sea defence,
pollution control and ocean studies.
-
3. Geodetic Survey:
• In geodetic survey, large areas of the earth surface are involved usually on
national basis where survey stations are precisely located large distances
apart. Account is taken of the curvature of the earth, hence it involves
advanced mathematical theory and precise measurements are required to be
made.
• Geodetic survey stations can be used to map out entire continent, measure
the size and shape of the earth or in carrying out scientific studies such as
determination of the Earth’s magnetic field and direction of continental drifts.
4. Plane Surveying
10
• In plane surveying relatively small areas are involved and the area under
consideration is taken to be a horizontal plane. It is divided into three
branches.
- Cadastral surveying
- Topographical surveying
- Engineering surveying
5. Cadastral surveying
• These are surveys undertaken to define and record the boundary of
properties, legislative area and even countries.
• It may be almost entirely topographical where features define boundaries with
the topographical details appearing on ordinance survey maps.
• In the other hand, accurately surveyed beacons or markers define boundaries,
corner or line points and little account may be taken of the topographical
features.
6. Topographical Survey
• These are surveys where the physical features on the earth are measured and
maps/plans prepared to show their relative positions both horizontally and
vertically.
11
• The relative positions and shape of natural and man –made features over an
area are established usually for the purpose of producing a map of the area of
for establishing geographical information system.
8. Engineering Survey
• These are surveys undertaken to provide special information for construction
of Civil Engineering and building projects.
• The survey supply details for a particular engineering schemes and could
include setting out of the work on the ground and dimensional control on such
schemes.
Reconnaissance:
• This is an exhaustive preliminary survey of the land to be surveyed. It may be
either ground reconnaissance or aerial reconnaissance survey.
12
• Reconnaissance is made on arrival to site during which an overall picture or
view of the area is obtained. The most suitable position of stations is selected,
the purpose of the survey and the accuracy required will be drawn, and finally
the method of observation will be established.
Objectives of reconnaissance
1. To ascertain the possibility of building or constructing route or track through
the area.
2. To choose the best one or more routes and record on a map
3. To estimate probable cost and draft a report.
13
WEEK TWO
BASIC PRINCIPLES IN SURVEYING
PRINCIPLE OF WORKING FROM WHOLE TO PART
• It is a fundamental rule to always work from the whole to the part. This implies
a precise control surveying as the first consideration followed by subsidiary
detail surveying.
• This surveying principle involves laying down an overall system of stations
whose positions are fixed to a fairly high degree of accuracy as control, and
then the survey of details between the control points may be added on the
frame by less elaborate methods.
• Once the overall size has been determined, the smaller areas can be surveyed
in the knowledge that they must (and will if care is taken) put into the confines
of the main overall frame.
• Errors which may inevitably arise are then contained within the framework of
the control points and can be adjusted to it. Thus they have no chance of
building up on accumulating throughout the whole survey.
IMPORTANCE OF SCIENTIFIC HONESTY
• Honesty is essential in booking notes in the field and when plotting and
computations in the office. There is nothing to be gained from cooking the
survey or altering dimensions so that points will tie-in on the drawing. It is
utterly unprofessional to betray such trust at each stage of the survey.
• This applies to the assistants equally as it does to the surveyor in charge.
Assistants must also listen carefully to all instructions and carry them out to the
later without questions.
CHECK ON MEASUREMENTS
• The second principle is that; all survey work must be checked in such away
that an error will be apparent before the survey is completed.
• Concentration and care are necessary in order to ensure that all necessary
measures are taken to the required standard of accuracy and that nothing is
omitted. Hence they must be maintained in the field at all times.
• Surveyor on site should be checking the correctness of his own work and that
of others which is based on his information.
14
• Check should be constantly arranged on all measurements wherever possible.
Check measurements should be conducted to supplement errors on field.
Pegs can be moved, sight rails altered etc.
• Survey records and computations such as field notes, level books, field books,
setting out record books etc must be kept clean and complete with clear notes
and diagrams so that the survey data can be clearly understood by others.
Untidy and anonymous figures in the field books should be avoided.
• Like field work, computations should be carefully planned and carried out in a
systemic manner and all field data should be properly prepared before
calculations start. Where possible, standardized tables and forms should be
used to simplify calculations. If the result of a computation has not been
checked, it is considered unreliable and for this reason, frequent checks
should be applied to every calculation procedure.
• As a check, the distances between stations are measured as they are plotted,
to see that there is correspondence with the measured horizontal distance.
Failure to match indicates an error in plotting or during the survey.
• If checks are not done on observations, expensive mistake may occur. It is
always preferable to take a few more dimensions on site to ensure that the
survey will resolve itself at the plotting stage, rather than to retire to site for
taking more measurements when things do not be in on the drawing board
which can often be expensive besides the frustration and time loss.
ACCURACY AND PRECISION
These terms are used frequently in engineering surveying both by manufacturers
when quoting specifications for their equipments and on site by surveyors to describe
results obtained from field work.
• Accuracy allows a certain amount of tolerance (either plus or minus) in a
measurement, while;
• Precision demands exact measurement. Since there is no such things as an
absolutely exact measurement, a set of observations that are closely grouped
15
together having small deviations from the sample mean will have a small
standard error and are said to be precise.
ECONOMY OF ACCURACY AND ITS INFLUENCE ON CHOICE OF
EQUIPMENTS
• Survey work is usually described as being to a certain standard of accuracy
which in turn is suited to the work in hand. Bearing in mind the purpose for
which the survey is being made, it is better to achieve a high degree of
accuracy than to aim for precision (exactness) which if it were to be altered
would depend not only on the instrument used but also on the care taken by
the operator to ensure that his work was free from mistake.
• Always remember that, the greater the effort and time needed both in the field
and in the office, the more expensive to survey will be for the client. The
standard accuracy attained in the field must be in keeping with the size of the
ultimate drawings.
• The equipment selected should be appropriate to the test in hand. An
important factor when selecting equipment is that the various instruments
should produce roughly the same order of precision. A steel chain best at an
accuracy of 1/500 to 1/1000 would be of little use for work requiring an
accuracy of 1/1000. Similarly, the theodolite reading to one second would be
pointless where a reading to one minute is sufficient.
• Having selected the equipment necessary, the work should be thoroughly
checked and if found wanting should be adjusted, repaired or replaced or have
allowance calculated for its deficiencies. This task will be less tedious if field
equipment is regularly maintained.
ERRORS IN SURVEYING
• Surveying is a process that involves observations and measurements with a
wide range of electronic, optical and mechanical equipment some of which are
very sophisticated.
• Despite the best equipments and methods used, it is still impossible to take
observations that are completely free of small variations caused by errors
which must be guided against or their effects corrected.
16
TYPES OF ERRORS
1. Gross Errors
• These are referred to mistakes or blunders by either the surveyor or his
assistants due to carelessness or incompetence.
• On construction sites, mistakes are frequently made by in – experienced
Engineers or surveyors who are unfamiliar with the equipment and method
they are using.
• These types of errors include miscounting the number of tapes length, wrong
booking, sighting wrong target, measuring anticlockwise reading, turning
instruments incorrectly, displacement of arrows or station marks etc.
• Gross errors can occur at any stage of survey when observing, booking,
computing or plotting and they would have a damaging effect on the results if
left uncorrected.
• Gross errors can be eliminated only by careful methods of observing booking
and constantly checking both operations.
2. Systematic or Cumulative Errors
• These errors are cumulative in effect and are caused by badly adjusted
instrument and the physical condition at the time of measurement must be
considered in this respect. Expansion of steel, frequently changes in electro
magnetic distance (EDM) measuring instrument, etc are just some of these
errors.
• Systematic errors have the same magnitude and sign in a series of
measurements that are repeated under the same condition, thus contributing
negatively or positively to the reading hence, makes the readings shorter or
longer.
• This type of error can be eliminated from a measurement using corrections
(e.g. effect of tension and temperature on steel tape).
• Another method of removing systematic errors is to calibrate the observing
equipment and quantify the error allowing corrections to be made to further
observations.
17
• Observational procedures by re-measuring the quantity with an entirely
different method using different instrument can also be used to eliminate the
effect of systematic errors.
3. Random or Compensating Errors
• Although every precaution may be taken certain unavoidable errors always
exist in any measurement caused usually by human limitation in
reading/handling of instruments.
• Random errors cannot be removed from observation but methods can be
adopted to ensure that they are kept within acceptable limits.
• In order to analyze random errors or variable, statistical principles must be
used and in surveying their effects may be reduced by increasing the number
of observations and finding their mean. It is therefore important to assume
those random variables are normally distributed.
18
WEEK THREE
EFFECTS OF ERRORS IN LINEAR MEASUREMENT AND THEIR
CORRECTIONS.
1. STANDARDIZATION
• Under a given condition, a tape has a certain nominal length which may
however tend to stretch with a lot of use under field conditions. The actual
length can be determined by comparing it with a known standard base or
against a reference tape.
• A base line for standardizing tapes should consist of two fixed points located
on site such that they are likely to be disturbed. These points could be nail in
pegs, but marks set into concrete blocks or pillars are preferable. The length of
the field tape is computed to the length of the baseline and the standardization
correction obtained as follows:.
Standardization = L (LB - LT) --------- (1)
LB
Where:-
L = Measured length
LB = Length of baseline
LT = Length of field tape along base line.
• If a reference tape is to be used, it should not be used for any field work and
should be checked by the manufacturer as often as possible.
• To avoid error, standardization should be done on smooth, flat surface such
as surfaced road or foot path.
• It is obvious that every tape length measured with a tape of incorrect length
would be in error (plus or minus) and the total error from this source would be
in direct proportion to the number of tape length measured.
• Standardization of steel tapes should be carried out frequently for each tape at
least once in every six months or whenever it is broken and mended.
• From standardization measurements a connection is computed as follows:
19
True distance = Actual length of the tape
Measured length Nominal length of the tape
Or dt = L1 ± L
dm L
Where :- L1 ± L = ±δL (Error per unit length)
L L
= dt = 1 ± δL
dm L
∴ dt = dm 1±δL standardization correction
L
Worked Examples
Example (1)
A chain of nominal length 20.00m when compared with a standard measures
20.05m. If this chain is used to measure a line AB and the recorded
measurement is 131.35m, what is the true length of AB.
Solution A:
Nominal length of chain = 20.00m
Actual length of chain = 20.05m
Measured length = 131.35m
δL = L1 - L
= 20.05 – 20.00 = 0.05m
Error per chain δL = 0.05 = 0.0025m
L 20.00
True length dt = dm 1 + δL
L
= 131.35 (1 + 0.0025)
= 131.680m
Solution B
True distance = Actual length of chain
20
Measured distance Nominal length of chain
dt = 131.35 20.05 = 131.680m
20.00
EFFECT OF STANDARDIZATION ON AREA
2
True distance (AT) = Actual length of tape/chain
Measured Area (Am) Nominal length of tape/chain
Example (2):
A metric chain of nominal length 20.00 is found to be 16cm too long and on using it
an area of 100 hectares is computed. Find the true area. (1 ha = 10000m2) NOTE:
(16.6cm = 0.16m)
Solution
Nominal length of chain = 20.00m
Actual length of chain = 20.16
Measured area (Am) = 100.00ha
2
True Area (AT) = Measured Area A. L. T
N. L. T
2
= 100.00 x 20.16
20.00
= 100. 00 x 1.016
= 101.670ha
EX AMPLE (3)
(a) A base line known to be precisely 100m long was measured with a nominal
20m tape. The observed length of the base was found to be 99.925m. What is
the actual length of the tape?
(b) The tape above was used in the measurements to provide calculated area of
3.162ha. What is the true area?
Solution
True distance = 100.00m
Measured length = 99.925m
Nominal length of tape (N.L.T) = 20.00m
21
True distance = A.L. T
Measured length N.L.T
100.00 = A.L.T
99.925 20.00
A. .L T. ═ 20.00 100.000 = 20.015m
99.925
2
(b) True Area (AT) = A.L. T
Measured length N.L.T
100.00 = A.L.T
99.925 20.00
A.L.T. = 2.162 20.015 = 3.16ha
20.000
SLOPE CORRECTION
Lengths measured on sloping land must be longer than those measured on flat land.
Measurements along a slope must be therefore reduced to horizontal plane before
being used for computations or plotting.
• This can be achieved by calculating a slope correction for the measured length
or by measuring the horizontal equivalent of the slope directly in the field.
• On ground which is of variable slope, stepping is the best method and needs
no calculation. Series of horizontal distance measurements are taken in short
length against a previously lined-in ranging rods and the points on the ground
below the free end are located by plumb bob or drop arrow as shown below;
22
Diagram
• As an alternative to stepping when measuring along regular slopes, the slope
angle (Ø) can be determined and the horizontal distance (D) calculated from
the measured slope distance (L). The correction
can be computed from:
Slope correction = [L ( 1 - Cos θ)]………………………..1
Where:-
L = measured length (slope distance)
θ = slope angle.
The horizontal distance can be determined shown below:
D = LCOS Ө…………………………………………….2
Diagram
• If the difference in light between the two stations is measured and the slope
between them is uniform, then;
23
Correction = h2
2L ………………………………………3
Where: h = difference in height
L = Measured length
D=L– h2
2L
SAG CORRECTION
When the ground between two points is very irregular, surface taping can prove to be
a difficult process and it may be necessary to suspend the tape above the ground
between the points in order to measure the distance between them. A tape
suspended in this way will sag under its own weight in the shape of a Catenary curve
as shown below:
Diagram
Sag correction nw2L3
24T2
Where n = number of unsupported length
w = weight per metre of tape = (mg)
L = unsupported length in metres
T= Tension applied to the tape in Newton
TEMPERATURE VARIATION
Steel tapes expand or contact with temperature variation. If the temperature during
measurement is different from that at which the tape was standardized the resulting
error will be accumulated in direct proportion to the number of tape length measured.
• In order to improve precision, the temperature of the tape has to be recorded
by using special surveying if already calibrated at a standard temperature. It is
necessary to have the tape in position for some time before readings are taken
to allow it to reach the ambient temperature.
• It is bad practice to measure a distance in the field in winter with a tape that
has just been removed from a heated office.
24
The temperature correction is given by:
Temperature correction = αL (tf – ts)
Where: α = Co-efficient of thermal expansion
L = Length of the tape used
tF = Temperature during measurement
ts = Tape standard temperature
NOTE: - Unless the field temperature differs considerably from that at which the
tape was standardized, this correction is usually negligible
TENSION CORRECTION
The tension applied to a tape should be the same as that applied when testing it
against standard. Variations in tension are bound to occur even when using a spring
balance, but resulting errors are small and tend to compensate each other.
If the tape is consistently pulled too hard or too lightly a cumulative error will arise and
this must be guarded against particularly when using linen and plastic tapes.
Tension correction is given as:
Tension correction = L (Tf – Ts)A E
Where L = Measured length
Tf = Tension applied to the tape (N)
Ts = Standard tension (N)
A = Cross sectional area of the tape (MM2)
E = Modules of elasticity for the tape material (N/mm2)
Example 4
The following data were obtained from a survey along a slope, calculate the
horizontal distance.
Measured length = 126.300m
Slope angle = 2o 34/
Different in height between the two points = 5.650m
Solution
L = 126.300m, θ = 2o 34/
θ = 2.567o
25
(i). Slope correction = L (1 – Cos θ)
= 126.300 (1 – Cos 2.567o)
= 126.300 (1-0.9990)
= 26.300 x 0.001
= 0.126m
Horizontal distance = L - correction
= 126.300 – 0.126
= 126.174m
(ii) Horizontal distance (D) = L Cos θ
= 126.300 x Cos 2.567o
= 126.300 x 0.990
∴D = 126.174m
(iii) Since the difference in height (h) = 5.650m
Slope correction - h2 = 5.6502
2L 2 x 126.300
Horizontal distance (d) = 126.300 – 0.126
= 126.174m
Example (5)
A 30m tape standardized in catenary as 29.9850m at 110N is used in the field with a
tension of 90N. Calculate the correction if the mass of the tape is 0.0312kg/m
Solution:-
Sag correction = nw2L3
24 T2
n = 1, standardized length (L) = 29.9850m
At T= 110N, mass of the tape (m) = 0.0312Kgm
Tension applied on field (T2) = 90N
Standardized chord length with 110N = 29.9850
Sag correction = (0.0312 x 9.81)2x 303
24 x 1102 = +0.0087
Standardized are length = 29.9850 + 0.0087
26
= 29.9937m
Sag correction in the field = (0.0312 x 9.81)2 x 303
24 x 902
= 0.0130m
∴ Reduced field length = 29.9937 – 0.0130
= 29.980.7m
EXERCISE
A steel tape of nominal length 30mm was used to measure a line AB by suspending it
between supports. The following measurements were recorded.
Line Length Slope angle Mean temp Tension
measured Applied
AB 29.872m 3o 401 5oC 120N
The standardized length of the tape against a reference tape was known to be
30.014m at 20oC and 50N tension.
If the tape weighs 0.17N/m and has a cross sectional area of 2mm2, calculate the
horizontal length of AB.
(Young modulus (E) for the tape materials is 200KN/mm2 and the co-efficient of
thermal expansion α= 0.000112 per o C.
27
WEEK FOUR
CHAIN SURVEYING
This is the simplest and oldest form of land surveying of an area using linear
measurements only. It can be defined as the process of taking direct measurement,
although not necessarily with a chain.
EQUIPMENTS USED IN CHAIN SURVEYING
These equipments can be divided into three, namely
(i) Those used for linear measurement. (Chain, steel band, linear tape)
(ii) Those used for slope angle measurement and for measuring right angle (Eg.
Abney level, clinomater, cross staff, optical squares)
(iii) Other items (Ranging rods or poles, arrows, pegs etc).
1. Chain:-
The chain is usually made of steel wire, and consists of long links joined by
shorter links. It is designed for hard usage, and is sufficiently accurate for
measuring the chain lines and offsets of small surveys.
Chains are made up of links which measure 200mm from centre to centre of
each middle connecting ring and surveying brass handless are fitted at each
end. Tally markers made of plastic or brass are attached at every whole metre
position or at each tenth link. To avoid confusion in reading, chains are
marked similarly form both end (E.g. Tally for 2m and 18m is the same) so that
measurements may be commenced with either end of the chain
There are three different types of chains used in taking measurement
namely:
i. Engineers chain
28
ii. Gunter’s chain
Iii Steel bands
2 Steel Bands:
This may be 30m, 50m or 100m long and 13mm wide. It has handles similar to
those on the chain and is wound on a steel cross. It is more accurate and but
less robust than the chain.
The operating tension and temperature for which it was graduated should be
indicated on the band.
29
3 Tapes:
Tapes are used where greater accuracy of measurements are required, such
as the setting out of buildings and roads. They are 15m or 30m long marked in
metres, centimeter and millimeters. Tapes are classified into three types;
i. Linen or Linen with steel wire woven into the fabric;
These tapes are liable to stretch in use and should be frequently tested
for length. They should never be used on work for which great accuracy
is required.
ii. Fibre Glass Tapes: These are much stronger than lines and will
not stretch in use.
iii. Steel tapes: These are much more accurate, and are usually used
for setting out buildings and structural steel works. Steel tapes are
available in various lengths up to 100m (20m and 30m being the most
common) encased in steel or plastic boxes with a recessed winding
lever or mounted on open frames with a folding winding lever.
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4. Arrows:
Arrow consists of a piece of steel wire about 0.5m long, and are used for
marking temporary stations. A piece of coloured cloth, white or red ribbon is
usually attached or tied to the end of the arrow to be clearly seen on the field.
5. Pegs
Pegs are made of wood 50m x 50mm and some convenient length. They are
used for points which are required to be permanently marked, such as
intersection points of survey lines.
Pegs are driven with a mallet and nails are set in the tops.
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6. Ranging Rod:
These are poles of circular section 2m, 2.5m or 3m long, painted with
characteristic red and white bands which are usually 0.5m long and tipped with
a pointed steel shoe to enable them to be driven into the ground. They are
used in the measurement of lines with the tape, and for marking


Use: 0.0512