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Basic Principles of Surveying (13)

Gates MacBain Associates

This unit provides an introduction to the basic principals of Engineering Surveying.

  • Aims and Objectives
    Aims and Objectives
  • Book
    Book
  • Website
    Website
  • Video/DVD
    Video/DVD
  • Self Assessment
    Self Assessment

Equipment
Aims
 
Aims and Objectives

 

At the end of this section you should be able to:

 

  • List  the types of equipment used in the surveying process

 

A wide range of equipment is used in engineering surveying. Using the activities above we will look in detail at the optical and associated equipment which might be required. The Fig 10 below shows the equipment that might be used in each case.

 

The equipment required for the survey of a building including internal measurements is covered in Unit 3.

When carrying out a linear survey the first stage is to walk over the site and decide upon the position of the survey lines and network of well conditioned triangles. Ranging rods are used to mark the corners of each triangle and a sketch is drawn in the survey book showing the survey lines and giving each point a station reference (usually alphabetical).

 

 

 

Equipment

Type of Survey

Linear

Levelling

Theodolite

Total Station

Optical Level

 

x

 

 

Theodolite

 

 

x

 

Total Station

 

 

 

x

Tripod

 

x

x

 

Levelling Staff

 

x

 

 

Prism Target

 

 

 

x

Abney Level

x

 

 

 

Ranging Rods

x

x

x

x

Steel Tape/Band

x

x

x

 

Synthetic Tape

x

 

 

 

Arrows

x

x

x

 

Pocket tape

x

 

 

 

Plumbob

 

 

x

x

Wooden Pegs

 

 

 

x

Survey Book

x

 

 

 

Levelling Book

 

x

 

 

Record Sheets

 

 

x

 

Pen or Pencil

x

x

x

 

 

 

 

 Figure 11: Suveying Equipment

 

Steel tapes or bands are graduated every millimetre and are either 30m or 50m long. They are calibrated to read true length when at 20º C and pulled at a pressure of 50 Newtons force. These tapes are coated with plastic or enamel for protection an ideally should be dried and wiped with an oily rag before being wound into its case. They are used for precise measurement on survey lines. The steel band is similar but is carried on a four arm open frame with a winder attached.

Pocket tapes are usually up to 5m in length and suitable for small offset measurements and the synthetic tapes usually graduated to the nearest 5mm are used to take offset and tie measurements. Because they are made of PVC or fibreglass these are prone to being stretched. Again this tape should be wiped prior to re-winding into the case.

.

 

Ranging rods or poles are usually 2m or 2.5m long and divided into 500mm bands alternating red and white. They are used to identify key points and forming straight lines during a survey.

 

Arrows are small steel pins usually about 300mm high with a coloured tag attached to enhance their visibility. These are used to mark survey or offset points as measurements and data collection proceeds. These may be substituted by pegs. There is a weighted version which is used when step measuring. This is known as a dropping arrow.

 

A plumbob is hung below a theodolite to position the instrument over a station prior to fine adjustment with the vertical scope.

 

A wide selection of equipment is available and examples of these can be seen by visiting a supplier such as the one shown below.

 

 

 


Website
 
Websites

Book
 
Publications

  • Irvine, W, (1995) Surveying for Construction, McGraw-Hill: Berkshire (Chapters 4 & 7)


Self_assessment
 
Task

 

  • Make a list of all the equipment you would require to carry out a linear survey and then collect data for contouring.