3. Cross Staff Survey
This type of survey is undertaken to locate
boundaries of a field or a field or plat and
determinations of its area.
Principle:
The principle of the survey is to divide the given area
in to no of right angled triangles and trapezoids and
to calculate and plot the areas of triangles and
trapezoids.
Instruments/Material Required:
Two Chains, arrows taps, ranging rods, cross-staff
and drawing material
4. P R O C E D U R E :
1 . F I R S T O F A L L F I R S T R A N G I N G R O D I S E S T A B L I S H E D A T P O I N T A A N D M A K E S
F I X E D S T A T I O N T A K I N G M E A S U R E M E N T R E V I S I N G P O I N T A T O T W O P E R M A N E N T
S T R U C T U R E S .
2 . S E C O N D R A N G I N G R O D I S E S T A B L I S H E D A T P O I N T B A N D F O R M A K E S F I X E D
S T A T I O N T A K I N G M E A S U R E M E N T R E V I S I N G P O I N T B T O T W O P E R M A N E N T
S T R U C T U R E S .
3 . E S T A B L I S H E D G R I D L I N E A T O B U S I N G R A N G I N G P R O C E D U R E B Y J U D G M E N T
O F E Y E A N D L A Y I N G C H A I N O N I T .
4 . R E M A I N I N G R A N G I N G R O D E S T A B L I S H E D A T P O I N T P , Q , R , A N D S , T O N
R I G H T A N D L E F T S I D E O F T H E G R I D L I N E A N D I T S M A Y B E P O I N T O F
P E R M A N E N T S T R U C T U R E A T D I F F E R E N T L O C A T I O N .
5 . S I G H T P O I N T P P E R P E N D I C U L A R T O G R I D L I N E U S I N G C R O S S S T A F F , L E T ’ S
M E E T I N G P O I N T I S P ’ O N G R I D L I N E .
6 . M E A S U R E D I S T A N C E O F A P ’ A N D P P ’ B Y C H A I N ( O N G R I D L I N E ) A N D
M E T A L L I C T A P E ( B E T W E E N P T O P ’ ) .
7 . W R I T E A L L O B S E R V A T I O N I N F I E L D B O O K O R L E V E L B O O K I M M E D I A T E L Y .
8 . R E P E A T S I G H T I N G P R O C E D U R E U S I N G C R O S S S T A F F , L E T ’ S M E E T I N G P O I N T I S
Q ’ , R ’ , S ’ , A N D T ’ O N G R I D L I N E .
9 . M E A S U R E D I S T A N C E O F A Q ’ , A R ’ , A S ’ A N D A T ’ B Y C H A I N ( O N G R I D L I N E ) A N D
Q Q ’ , R R ’ , S S ’ , T T ’ U S I N G M E T A L L I C T A P E R E S P E C T I V E L Y .
1 0 . W R I T E A L L O B S E R V A T I O N I N F I E L D B O O K O R L E V E L B O O K R E S P E C T I V E L Y .
1 1 . W H E N C O M P L E T E A L L O B S E R V A T I O N R E M O V E S A L L R A N G I N G R O D S A N D
P A C K E D I N I T S C O V E R .
5.
6. (2) CLASSROOM WORK: –
1. DRAW A COMPLETE FIGURE IN FIELD BOOK USING FIELD
OBSERVATION.
2. DRAW A LINE MEETING POINT P TO S AND R TO T ON FIELD BOOK OR
LEVEL BOOK.
3. CALCULATE THE AREA OF FIELD BY SUBTRACT OUT SIDE
(REMAINING) AREA OF MEETING LINE IN TOTAL AREA IN FIELD BOOK
OBSERVATION TABLE: –
7. C A L C U L A T I O N S O F F I E L D A R E A :
B Y T H I S M E T H O D O F S U R V E Y , T H E F I E L D A S
D I V I D E D I N T O R I G H T A N G L E D T R I A N G L E S A N D
T R A P E Z O I D S A R E C A L C U L A T E D A S U N D E R :
A R E A O F R I G H T - A N G L E D T R I A N G L E = ½ B A S E X
H E I G H T .
A R E A O F T R A P E Z O I D = S U M O F P A R A L L E L
S I D E S / 2 X H E I G H T .
A D D T H E A R E A S O F A L L T H E T R I A N G L E S &
T R A P E Z O I D S A N D S U M I S E Q U A L T O T H E T O T A L
O F A F I E L D .
10. SOME BASIC SURVEYING INSTRUMENTS ARE
REQUIRED FOR PLANE TABLE SURVEYING.
FOLLOWINGS ARE THE GENERAL PLANE
TABLE SURVEY EQUIPMENT.
1. PLANE TABLE
2. ALIDADE FOR SIGHTING (TELESCOPIC OR
SIMPLE)
3. PLUMB BOB AND PLUMB FORK
4. COMPASS
5. SPIRIT LEVEL
6 .CHAIN
7. RANGING RODS
8. TRIPOD
9. DRAWING SHEET AND DRAWING TOOLS
10.PAPER CLIPS OR SCREWS
11. SIMPLE ALIDADE
ALIDADE COMPASS HAS TWO EDGES. ONE
STRAIGHT AND OTHER ONE IS BEVELED. THE
STRAIGHT EDGE IS MADE OF BRASS OR
GUNMETAL AND WORKS AS A RULER. THE
BEVELED EDGE IS CALLED THE FIDUCIAL EDGE.
IT CONSISTS OF TWO VANES AT THE ENDS.
THE VANES ARE HINGED AND CAN BE FOLDED
WHEN THE ALIDADE IS NOT IN USE.
ONE OF THE VANES IS THE SIGHT VANE OR
THE EYE VANE. IT HAS THREE EQUIDISTANT
NARROW SILTS. THE SURVEYOR LOOKS
THROUGH THESE SILTS TOWARDS THE
OBJECT OR STATION. THE OTHER VANE
WHICH IS KNOWN AS OBJECT VANE IS OPEN
AND A FINE THREAD IS STRETCHED BETWEEN
THE TOP AND BOTTOM SILT.THIS THREAD IS
USED TO ESTABLISH A HORIZONTAL LINE OF
SIGHT PARALLEL TO THE RULER. THE
PROBLEM WITH SIMPLE ALIDADE COMPASS IS
THAT IT CAN BE USED ONLY WHEN THE
ELEVATIONS OF THE OBJECTS ARE LOW.
12. TELESCOPIC ALIDADE
WHILE THE PLANE ALIDADE ONLY
TOOK HORIZONTAL SIGHTS, THIS
TELESCOPIC ALIDADE IS USED TO
TAKE INCLINED SIGHTS. IT IS USED TO
INCREASE THE ACCURACY OF THE
SIGHT TAKEN. A SMALL SPIRIT LEVEL
TUBE IS PROVIDED WITH THE
TELESCOPE SO THAT THE ALIDADE
CAN BE LEVELED WITH THE
WORKING STATION. A SCALE IS
MOUNTED ON THE HORIZONTAL
AXIS. LINES ARE DRAWN ALONG THE
STRAIGHT RULER. IT IS ALSO
MOUNTED WITH A VERTICAL CIRCLE
THAT GIVES US THE ANGLE OF THE
OBJECT WITH THE HORIZONTAL
AXIS.
13. Plumbing Fork and Plumb Bob
Plumbing fork is a U-shaped
metal frame that has two
different types of arms. One is
horizontal (upper hand) and
the other is inclined at a
certain angle(lower hand).The
upper arm has a pointer at the
end while the lower arm has a
hook from which plumb bob is
suspended.
When the plumbing fork is
kept on the table it has to pass
through a particular point (the
pointer in the other hand). The
plumb bob helps in centering.
14. Compass
Compass is of two types-
Prismatic Compass
Surveyor’s Compass
Both the compasses are used to
navigate the surveying terrain.
These are strictly used to
determine the bearing of the
land that has been traversed.
Both prismatic and surveyor’s
compass has following parts:-
Magnetic needle,
Graduated circle,
Vanes for line of sight, and
A box to keep them in place
15. SPIRIT LEVEL
WHEN PLANE TABLE
SURVEYING IS CARRIED OUT
IT IS REALLY ESSENTIAL TO
KNOW WHETHER THE
WORKING STATION
(SURFACE) IS HORIZONTAL
OR VERTICAL. SPIRIT LEVEL IS
USED FOR THIS PURPOSE. A
BUBBLE (MERCURY IS
USUALLY USED) IS PUT INSIDE
THE TUBE. THE TUBE HAS AN
UPWARD CURVATURE
WHICH MAKES THE BUBBLE
REMAIN IN CENTER UNLESS
THE SURFACE IS INCLINED.
16. RANGING ROD
A RANGING ROD IS AN
INSTRUMENT EXTENSIVELY
USED FOR MARKING THE
POSITION OF DIFFERENT
SURVEYING STATIONS/PEGS
AND FOR TAKING SIGHTS OF
THOSE STATIONS. IT IS ALSO
USED FOR RANGING FOR
STRAIGHT LINES.
