The document discusses different aspects of leveling. It defines leveling as determining the relative heights or elevations of different points on or below the earth's surface. It describes different types of levels used including dumpy level, wye level, Cooke's reversible level, Cushing's level, modern tilting level, and automatic level. It also discusses terms used in leveling such as level surface, level line, horizontal plane, horizontal line, vertical line, and vertical plane. Finally, it explains different methods of leveling including barometric leveling, trigonometric leveling, spirit leveling, and precise leveling.

2. PRESENTED BY
SAIF UR REHMAN
SECTION A
CLASS NO 08
PRESENTED TO
DR KHANSHEZADA SIR

3. TOPIC OF PRESENTATION
LEVELING

4. DEFINITION OF LEVELING
LEVELING MAY BE DEFINED AS THE ART OF DETERMINING THE RELATIVE HEIGHTS OR
ELEVATION OF DIFFERENT POINTS OR OBJECTS ON OR BELOW THE SURFACE OF EARTH AND
TO DETERMINE THE UNDULATION OF THE GROUND SURFACE IN A VERTICAL PLANE

5. USES OF LEVELLING
LEVELLING IS DONE FOR THE FOLLOWING PURPOSES
TO PREPARE A CONTOUR MAP FOR FIXING SITES FOR RESERVOIRS, DAMS, BARRAGES,
ETC., AND TO FIX THE ALIGNMENT OF ROADS, RAILWAYS, IRRIGATION CANALS, AND SO ON.
TO DETERMINE THE ALTITUD.ES OF DIFFERENT IMPORTANT POINTS ON A HILL OR TO
KNOW THE REDUCED LEVELS OF DIFFERENT POINTS ON OR BELOW THE SURFACE OF THE
EARTH. TO PREPARE A LONGITUDINAL SECTION AND CROSS-SECTIONS OF A PROJECT
(ROADS, RAILWAYS, IRRIGATION CANALS, ETC.) IN ORDER TO DETERMINE THE VOLUME OF
EARTH WORK.
TO PREPARE A LAYOUT MAP FOR WATER SUPPLY, SANITARY OR DRAINAGE SCHEMES.

6. TERMS USE IN LEVELING
LEVEL SURFACE:
ANY SURFACE PARALLEL TO THE MEAN SPHEROIDAL SURFACE OF
THE EARTH IS SAID TO BE A LEVEL SURFACE. SUCH A SURFACE IS OBVIOUSLY CURVED. THE
WATER SURFACE OF A STILL LAKE IS ALSO CONSIDERED A LEVEL SURFACE.

7. LEVEL LINE:
ANY LINE LYING ON A LEVEL SURFACE IS CALLED A LEVEL LINE. THIS LINE
IS NORMAL TO THE PLUMB LINE (DIRECTION OF GRAVITY) AT ALL POINTS.
HORIZONTAL PLANE:
ANY PLANE TANGENTIAL TO THE LEVEL SURFACE AT ANY POINT IS
KNOWN AS THE HORIZONTAL PLANE. IT IS PERPENDICULAR TO THE PLUMB LINE WHICH
INDICATES THE DIRECTION OF GRAVITY.

8. HORIZONTAL LINE:
ANY LINE LYING ON THE HORIZONTAL PLANE IS SAID TO BE A
HORIZONTAL LINE. IT IS A STRAIGHT LINE TANGENTIAL TO THE LEVEL LINE.
VERTICAL LINE:
THE DIRECTION INDICATED BY A PLUMB LINE (THE DIRECTION OF GRAVITY)
IS KNOWN AS THE VERTICAL LINE. THIS LINE IS PERPENDICULAR TO THE HORIZONTAL LINE.
VERTICAL PLANE:
ANY PLANE PASSING THROUGH THE VERTICAL LINE IS KNOWN AS THE VERTICAL PLANE.

9. PARALLAX:
THE APPARENT MOVEMENT OF THE IMAGE RELATIVE TO THE CROSSHAIRS IS KNOWN AS
PARALLAX.
THIS OCCURS DUE TO IMPERFECT FOCUSING, WHEN THE IMAGE DOES NOT FALL IN THE
PLANE OF THE DIAPHRAGM. • THE PARALLAX IS TESTED BY MOVING THE EYE UP AND
DOWN.
 IF THE FOCUSING IS NOT CORRECT, THE IMAGE MOVES UP AND DOWN RELATIVE TO THE
CROSS-HAIRS.
IF THE FOCUSING IS PERFECT, THE IMAGE APPEARS FIXED TO THE CROSS-HAIRS.
THE PARALLAX MAY BE ELIMINATED BY PROPERLY FOCUSING THE EYEPIECE AND
TELESCOPE (DISCUSSED IN TEMPORARY ADJUSTMENTS).
.

10. TYPES OF LEVEL
DUMPY LEVEL:
THE TELESCOPE OF THE DUMPY LEVEL IS RIGIDLY FIXED TO ITS SUPPORTS. IT CANNOT BE REMOVED FROM ITS
SUPPORTS NOR CAN IT BE ROTATED ABOUT ITS LONGITUDINAL AXIS. THE INSTRUMENT IS STABLE AND
RETAINS ITS PERMANENT ADJUSTMENT FOR. A LONG TIME. THIS INSTRUMENT IS COMMONLY USED.

11. WYE LEVEL (Y-LEVEL):
THE TELESCOPE IS HELD IN TWO 'Y' SUPPORTS. IT CAN BE REMOVED
FROM THE SUPPORTS AND REVERSED FROM ONE END OF THE TELESCOPE TO THE OTHER END. THE 'Y'
SUPPORTS CONSIST OF TWO CURVED CLIPS WHICH MAY BE RAISED. THUS THE TELESCOPE CAN BE ROTATED
ABOUT ITS LONGITUDINAL AXIS.
COOKE'S REVERSIBLE LEVEL:
THIS IS A COMBINATION OF THE DUMPY LEVEL AND THE Y-LEVEL. IT IS
SUPPORTED BY TWO RIGID SOCKETS. THE TELESCOPE CAN BE ROTATED ABOUT ITS LONGITUDINAL AXIS;
WITHDRAWN FROM THE SOCKET AND REPLACED FROM ONE END OF THE TELESCOPE TO. THE OTHER END.

12. CUSHING'S LEVEL:
THE TELESCOPE CANNOT BE REMOVED FROM THE SOCKETS AND ROTATED
ABOUT ITS LONGITUDINAL AXIS. THE EYEPIECE AND OBJECT GLASS ARE REMOVABLE AND CAN BE
INTERCHANGED FROM ONE END OF THE TELESCOPE TO THE OTHER END.
MODERN TILTING LEVEL:
THE TELESCOPE CAN BE TILTED SLIGHTLY ABOUT ITS HORIZONTAL AXIS WITH THE
HELP OF A TILTING SCREW. IN THIS INSTRUMENT, THE LINE OF COLLIMATION IS MADE HORIZONTAL FOR
EACH OBSERVATION BY MEANS OF THE TILTING SCREW.

13. AUTOMATIC LEVEL:
THIS IS ALSO KNOWN AS THE SELF-ALIGNING LEVEL. THIS INSTRUMENT IS LEVELLED
AUTOMATICALLY WITHIN A CERTAIN TILT RANGE BY MEANS OF A COMPENSATING DEVICE
(THE TILT COMPENSATOR).

14. PRECISE LEVELING
PRECISE LEVELING IS A PARTICULARLY ACCURATE METHOD OF DIFFERENTIAL LEVELING
WHICH USES HIGHLY ACCURATE LEVELS AND WITH A MORE RIGOROUS OBSERVING
PROCEDURE THAN GENERAL ENGINEERING LEVELING.
IT AIMS TO ACHIEVE HIGH ORDERS OF ACCURACY.
IT IS A SPECIAL SYSTEM OF LEVELING CHIEFLY EMPLOYED FOR ESTABLISHING
BENCHMARKS WITH HIGH PRECISION AT WIDELY DISTRIBUTED POINTS.
IT IS PRINCIPALLY CONDUCTED BY STATE AGENCY SUCH SURVEY DEPARTMENT OF
PAKISTAN.
IT REQUIRED HIGHLY REFINED INSTRUMENTS AND METHODS AND GREATEST CARE IN THE
FIELD.

15. METHOD OF LEVELING
BAROMETRIC LEVELLING:
 BAROMETRIC LEVELLING MAKES USE OF THE PHENOMENON THAT
DIFFERENCE IN ELEVATION BETWEEN TWO POINTS IS PROPORTIONAL TO
THE DIFFERENCE IN ATMOSPHERIC PRESSURES AT THESE POINTS.
A BAROMETER, THEREFORE, MAY BE USED AND THE READINGS
OBSERVED AT DIFFERENT POINTS WOULD YIELD A MEASURE OF THE
RELATIVE ELEVATIONS OF THOSE POINTS.
AT A GIVEN POINT, THE ATMOSPHERIC PRESSURE DOES NOT REMAIN
CONSTANT IN THE COURSE OF THE DAY, EVEN IN THE COURSE OF AN
HOUR. • THE METHOD IS, THEREFORE, RELATIVELY INACCURATE AND IS
LITTLE USED IN SURVEYING WORK EXCEPT ON RECONNAISSANCE OR
EXPLORATORY SURVEYS.

16. TRIGONOMETRIC LEVELLING (INDIRECT LEVELLING):
TRIGONOMETRICAL OR INDIRECT LEVELLING IS THE PROCESS OF
LEVELLING IN WHICH THE ELEVATIONS OF POINTS ARE COMPUTED FROM
THE VERTICAL ANGLES AND HORIZONTAL DISTANCES MEASURED IN THE
FIELD, JUST AS THE LENGTH OF, ANY SIDE IN ANY TRIANGLE CAN BE
COMPUTED FROM PROPER TRIGONOMETRIC RELATIONS.
 N A MODIFIED FORM CALLED STADIA LEVELLING, COMMONLY USED IN
MAPPING, BOTH THE DIFFERENCE IN ELEVATION AND THE HORIZONTAL
DISTANCE BETWEEN THE POINTS ARE DIRECTLY COMPUTED FROM THE
MEASURED VERTICAL ANGLES AND STAFF READINGS.

18. SPIRIT LEVELLING (DIRECT LEVELLING):
IT IS THAT BRANCH OF LEVELLING IN WHICH THE VERTICAL DISTANCES WITH RESPECT TO A
HORIZONTAL LINE (PERPENDICULAR TO THE DIRECTION OF GRAVITY) MAY BE USED TO
DETERMINE THE RELATIVE DIFFERENCE IN ELEVATION BETWEEN TWO ADJACENT POINTS.
A HORIZONTAL PLANE OF SIGHT TANGENT TO LEVEL SURFACE AT ANY POINT IS READILY
ESTABLISHED BY MEANS OF A SPIRIT LEVEL OR A LEVEL VIAL.
IN SPIRIT LEVELLING, A SPIRIT LEVELAND A SIGHTING DEVICE (TELESCOPE) ARE COMBINED
AND VERTICAL DISTANCES ARE MEASURED BY OBSERVING ON GRADUATED RODS PLACED
ON THE POINTS.
THE METHOD IS ALSO KNOWN AS DIRECT LEVELLING.
IT IS THE MOST PRECISE METHOD OF DETERMINING ELEVATIONS AND THE ONE MOST
COMMONLY USED BY ENGINEERS.