Civil Engineering

The following five corrections may be found for the measured lengths of tape: (i)   Corrections for absolute length (ii)  Corrections for pull (iii) Corrections for temperature (iv) Corrections for slope and (v) Corrections for sag.

Errors in chaining may be classified as: (i) Personal errors (ii) Compensating errors, and (iii) Cumulating errors. Personal Errors Wrong reading, wrong recording, reading from wrong end of chain etc., are personal errors. These errors are serious errors and cannot be detected easily. Care should be taken to avoid such errors. Compensating Errors These errors…

When a survey line is longer than a chain length, it is necessary to align intermediate points on chain line so that the measurements are along the line. The process of locating intermediate points on survey line is known as ranging. There are two methods of ranging viz., direct ranging and reciprocal ranging. Direct Ranging…

As soon as the survey party arrives in the field the following details are entered in the field book: (i) Title of the survey work (ii) The date of survey (iii) The names of the members of the party. The field work may be divided into the following: (i) Reconnaissance survey. (ii) Marking stations, drawing…

All observations and measurements taken during chain surveying are to be recorded in a standard field book. It is a oblong book of size 200 mm × 120 mm, which can be carried in the pocket. There are two forms of the book (i) single line and (ii) double line. The pages of a single book are…

Lateral measurements to chain lines for locating ground features are known as offsets. For this purpose perpendicular or oblique offsets may be taken . If the object to be located (say road) is curved more number of offsets should be taken. For measuring offsets tapes are commonly used. For setting perpendicular offsets any one of the following…

The following points should be considered in selecting station points: (i) It should be visible from at least two or more stations. (ii) As far as possible main lines should run on level ground. (iii) All triangles should be well conditioned (No angle less than 30º). (iv) Main network should have as few lines as possible….

Various technical terms used in connection with the network of the triangles in surveying are explained below: Station: Station is a point of importance at the beginning or at the end of a survey line. Main station: These are the stations at the beginning or at the end of lines forming main skeleton. They are denoted as…

Chain survey is suitable in the following cases: (i) Area to be surveyed is comparatively small (ii) Ground is fairly level                         (iii) Area is open and (iv) Details to be filled up are simple and less. In chain surveying only linear measurements are made i.e. no angular measurements are made. Since triangle is the only figure…

The following instruments are required for measurements with chain and tape: (i) Arrows (ii) Pegs (iii) Ranging rods and ranging poles (iv) Offset rods (v) Laths (vi) Whites (vii) Plumb bobs and (viii) Line ranger. Arrows When the length of the line to be measured is more than a chain length, there is need to mark…