# Basic Civil Engineering (3110004)

BE | Semester-1   Winter-2019 | 08-01-2020

## Q2) (a)

#### Define the following terms: 1) Datum 2) Change point 3) Contour interval.

##### Datum
Datum is the level surface whose elevation is known/assumed. The vertical distances of different points are measured from the datum surface in a vertical plane.

##### Change Point
It is the point which indicates shifting of instrument. At this point, before shifting, FS is taken and after shifting the instrument, BS is taken from the next setup at the same staff position.

##### Contour Interval
The vertical distance between any two consecutive contours is known as a contour interval.