Lesson 11 : Tape measurmenets 4

Types of tapes

According to graduation

• • In metric or imperial units

• •Different location of zero mark

• •Least graduation interval

                Millimeters, centimeters, or decimeters           
         

 

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Lesson 10 : Tape measurmenets 3

Equipments used with taping

1) Plumb bob 

• Used to ensure a horizontal reading is obtained .

2) Range poles 

• painted alternately red and white .
• Used as upright guides when chaining or marking turning points .

Types of tapes : great variety exists :

1) According to the material : 

• steel and steel alloy 
• metallic or non-metallic 
• polymers 
• Invar 

       1) nickle - steel alloy .

       2) with very low coefficient of thermal expansion .

       3) Used for precise measurements .

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Lesson 9 : Tape measurmenets 2

Units of length :

1) Metric system 

• Adopted as international system .
• The meter is the length of the path traveled by light in vacuum during a time interval of 1/299792458 of a second .

2) Imperial ( English ) system : 

• foot .
• the popular belief is that original standard was the length of a man's foot .
• the foot used today is the imperial foot , which is defined to be exactly 0.3048 meters .

Units of Area :

1) Imperial ( English ) system ; 

• square foot , yard and inch 
• 1 Acre = 43560 square feet 

2) Metric 

• square meter , kilometer , decimeter , centimeter and millimeter .
• 1 hectare = 10000square meters 

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Lesson 8 : Tape measurmenets 1

Introduction

1) one of the fundamental operation in surveying is distance measurement  .

2) distance measurement can be done by :

1. passing 
2. wheels 
3. taping 

• also the term chaining is used .
• the oldest instrument used is chain 
• later on tape 

3) stadia method 

• the distance is computed from angle measurements and staff readings .

4) electronic distance measurement - the most modern technique .

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Lesson 7 : Taping

Taping 

Considered by many to be the most accurate of manual measurement . 

A crew of two persons are referred to as a head chainman and a rear chainman  

Accuracy of measuring with a tape come from knowing the equipment . 

Source of errors when taping 

• Tape of incorrect length 
• 
  
• Tape not horizontal 
• 
  
• Incorrect alignment 
• 
  
• Random errors  

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Lesson 6 : Sources Of Errors

 Sources Of Errors 

1) personal errors 

no surveyor has perfect senses of sight and touch 

2) Instrument errors 

devices cannot be manufactured perfectly wear and tear and 

compatibility with other components  .

3 ) Natural error 

temperature , wind , moisture , magnetic variation , etc .

4) Systematic error 

Known as cumulative errors .

Correction can be made to eliminate them .  

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Lesson 5 : Conversions of unit of measuring

Conversions of unit of measuring 

As a student you must store these basic parameters in your mind to use it but in future you can used a lot of alternatives to convert between units 

• 1 yard = 3 feet 
• 1 meter = 39.37 inch = 3.2808 feet
• 1 degree = 1/ 360 of the angle around a point  
• 1 degree = 60 minutes 
• 1 radian = 57.3 degrees 
• 1meter = 100 cm = 1000 mm = 1.0936 yd 
• 1 kilometer = 1000 m = 0.6214 mile 
• 1 foot = 12 inch 
• 1 mile = 1760 yd 
• 1 hectare = 10000m square 
• 1 square kilometer = 100 hectare 

This the most important point you can use in conversions . 

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