Preliminary Survey || Method || Important Point-Highway Engineering - Civil Engineering

Friday, 15 March 2019

Preliminary Survey || Method || Important Point-Highway Engineering

The survey of highway can be completed in four Stage(map study, reconnaissance survey, preliminary survey, final location and detailed survey), the third stage is known as Preliminary Survey.

Preliminary Survey

The art of finding the details of alternative alignments found suitable during the reconnaissance survey is called preliminary survey.
Preliminary Survey -highway
Preliminary Survey
In this survey, the routes selected during reconnaissance survey, are actually located on the ground. The highway engineer collects necessary data in the field and prepares drawings and approximate estimates to compare the alternative routes and to finalize the best alignment from all consideration. 
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Method Of Preliminary Survey

The preliminary survey is carried out by any one of the following methods.

1. Conventional Method

In conventional method, a survey party carries out surveys by using the field equipments like chain, metallic tape, prismatic compass, leveling instrument, plane table, theodolite etc. The survey party takes measurements, collects topographical and other data and also conduct soil survey.

2. Modern Approach

In this method, necessary topographic and other maps including details of soil and geographical features of the area are obtained by Arial survey.

Important Point to be Followed during Preliminary Survey

  1. The angle of traverse should be very accurately measured by theodolite.
  2. The length of the centre line should be measured by using very good and accurate chaining method or by techometry or by modern instruments.
  3. Cross section levels should be taken at suitable intervals.
  4. Drainage investigations and hydrological data are to be collected carefully so as to estimate the type, number and approximate size of cross drainage structures.
  5. Soil survey is to be carried out very carefully.