Chaining on Sloping Ground (Simple Notes) When measuring distances on a hill or slope, we always need to find the flat horizontal distance , not the actual sloped ground distance. There are two main ways to do this: 1. Direct Method (Stepping Method) In this method, you measure the flat horizontal distance directly on the field by creating small, flat steps. Best For: Short, bumpy, irregular, or gentle slopes. How it works (Step-by-Step): Start: The Follower holds the 0-end of the tape flat on the starting ground point A. Stretch: The Leader pulls a short, comfortable length of the tape forward and lifts it up until it looks perfectly flat and straight by eye judgment. Drop: Because the front end of the tape is hanging in the air, the Leader drops a plumb-bob (a weight on a string) down to find the exact vertical point on the ground. Mark & Repeat: They stick an arrow into that ground point. The Follower moves to this new arrow, and they repeat the steps all the way u...
ERRORS IN SURVEYING
There is a possibility of the following types of errors creeping into the survey work
(1) Natural error
(2) Instrumental error
(3) Personal error
(1) Natural error
This errors in survey comes in due to bad weather , storm ,heat,rains, scorching sun , moisture, magnetic clash . survey work should be stopped in bad weather.
(2) Instrumental error
This error creeps in due to surveying with defective or faulty instruments. The measurements obtained on the field with such instrument would not be trusted.
(3) Personal error
The surveyor not being healthy for the survey work ,or his being weak sighted . incorrect identification of the aim , drawing projections incorrectly , carelessness or forgetfulness in noting down measurements not understanding the sign of the assistant correctly, being disinterested in work are some such personal errors which can be avoided by being attentive.
Classification errors
(1) Cumulative error
(2) Compensating error
(1) Cumulative error
Cumulative error proceed only in one direction and as the work progresses, the error keeps getting accumulated.due to such an error the measurements of the survey work are either greater or less than the actual measurements .
The error that increases the measurements from the original is called positive error ,
The error that shows a smaller value for the measurements or size than the original, it is called negative error.
(2) Compensating Error
This type of error, sometimes increases and sometimes decrease, and thus cancel out each other .As a result, the Compensating errors get nullified in the end.
Phases of survey
The following are the steps of survey
(1). Planning
(2) care and adjustment of instruments
(3) field work and observation
(4) office work
Methods of linear distance measurements
There are two methods of measuring linear distance .
(1) Direct method
(2) Indirect method
(1) Direct method
(1) Pacing
Surveyor should walk from one point to the other with normal pace and counting steps. Now these number of steps is multiplied by the average distance of one step to find the rough distance. An ordinary person's step is taken as 75 cm to 80 cm.
(2) By Passometer
This instrument resemble a pocket watch which a surveyor ties to his leg and when the surveyor walk this instrument counts the steps and shows it on dial, which can be multiplied by the average step distance to know the rough distance.
(3) By Perambulator
This is a wheeled instrument on the handle bar of which is fitted a dial. The Perambulator is held by its handle and is run on the line upto the distance to be measured.the distance travelled comes directly on the dial.
(4) By Pedometer
The pedometer is also similar to the Passometer, the difference is that instead of it counting the steps it directly gives the distance travelled in meters.
(5) By Odometer
This instrument is tried to the wheel of a cycle/vehicle and it counts the turns of the wheel, which multiplied by the circumference of the wheel gives the land distance covered.
(6) Speedometer
This instrument is there in the automobiles (cars ,trucks,buses etc )and on the basis of the distance covered directly provides the speed of the vehicle,whereas the Odometer gives the number of turns taken by the wheel.
(7) Chain and tapes
To know the distance more accurately in survey work, chains and tapes are used. These are of many types- for limited distances the tape is a satisfactory tool.
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