civilwartestseries

MINOR INSTRUMENTS  1. HAND LEVEL • A hand level is a small leveling instrument which is held in hand while levelling.  • It is used for approximate determination of elevations in  • reconnaissance,  • preliminary surveying,  • locating contours on the ground  • for taking short cross-sections in profile  2. ABNEY LEVEL • Modified hand level  • Can be used as a hand level for levelling and as a clinometer for slopes  • Vertical scale is extended type  3. CLINOMETER • Aka tangent clinometer  • Used to measure elevation of two points by measuring inclination of line of sight  • Used for plane tabling  4. CEYLON GHAT TRACER  • Used for measuring slopes  • It is specifically used to set out grade contour in preliminary survey of road in hills  5. SEXTANT  • A sextant is an instrument used for measurement of the horizontal and vertical angles. • Arrangement of 2 mirrors helps observer to sight 2 objects simul...

TACHEOMETRIC SURVEYING  • Tachometry is a branch of angular surveying in which the horizontal and vertical distances ofpoints are obtained by instrumental observations.  • Chaining is entirely eliminated in tachometry.  • This method is most rapid but less accurate.  • The accuracy of tachometry is less than that of chaining  • The primary object of tacheometry is the preparation of contoured map or plan.  • The instruments used in tacheometry are a tacheometer and a leveling or stadia rod.  • Tacheometer is a transit theodolite having a stadia telescope ie, a telescope fitted with two additional cross hairs called stadia hairs. • Stadia rod is 5 cm to I5 cm wide and 3 to 4m long. It is graduated in meters, decimeters and centimeters. • For short sights up to 100m a stadia theodolite and a leveling staff may be used. But for long sights, say more than 300m a tacheometer and stadia rod are required.  TACHEOMETRIC METHOD  I. STADIA METHODS...

THEODOLITE SURVEY THEODOLITE SURVEY  • Universal instrument  • Accurately measure horizontal and vertical angle with accuracy pf 20 sec  • The diameter of the graduated circle on the lower plate determines the size of theodolite  • Size of theodolite varies from 8cm to 25cm  • 8 cm to 12cm instruments are used for general survey and engineering work  • 14cm to 25cm instruments arc used for triangulation work.  CLASSIFICATION OF THEODOLITE  1. Transit Theodolite: If the telescope of a theodolite can be revolved through a complete revolution about its horizontal axis in the vertical plane, it is called a transit theodolite .  2. Non transit theodolite : If the telescope of a theodolite cannot be revolved through a complete revolution about its horizontal axis in the vertical plane, it is called a non-transit theodolite. eg: Plane or Y, and fa-crest theodolite.  3. Vernier and manometer theodolite : According to verniers or micrometers fitt...

KERALA PSC NOTES BASED ON CONTOURING CONTOUR / CONTOUR LINE  • Imaginary line passing through points of equal elevation  • Formed by the intersection of level surface with the ground  • Maps showing contour lines are called as contour maps  • Contour lines underwater called as : fathom , bathymetric curves, submarine contour  CONTOUR INTERVAL  • The vertical distance between any two consecutive contours is called the contour interval  • For important work CI will be shorter  • Constant contour interval is needed throughout the map  • Contour interval ∝ slope ∝ 1/scale  HORIZONTAL EQUIVALENT  • The horizontal distance between any two consecutive contours  CONTOUR GRADIENT / GRADE CONTOUR  • A line lying on the ground surface and having a constant inclination to horizontal  • Infinite number of contour gradient can be set out through a point  COMMONLY USED CONTOUR INTERVALS  for building sites : 0.2 - 0.5 For ...

Branch of science dealing with  i. Finding elevation of a point wrt other point  ii. Establishing a point at a given elevation  TERMS  i. LEVEL SURFACE : surface parallel to mean spheroidal surface of earth , perpendicular to plumb line  ii. LEVEL LINE : a line liying on level surface  iii. HORIZONTAL SURFACE : a surface tangential to the level surface  iv. HORIZONTAL LINE : a line on Horizontal surface  v. DATUM : any arbitrarily assumed level surface or line from which vertical distances are measured  vi. ELEVATION /RL/ SPOT LEVEL : The elevation of a point is its vertical distance above or below the datum.  vii. MEAN SEA LEVEL : average sea level for 19 years. In india Mumbai is taken as datum  viii. BENCH MARK : a fixed reference point at known elevation.  a) GTS benchmark : established by survey of India , high precision  b) Permanent benchmark : established by state gov. wrto gts.  c) Temporary benchmark : e...

Plane tabling is a graphical method of surveying in which the field work and plotting are done simultaneously  • It is most suitable for filling-in of the details in a plot  • Used in small scale work with low accuracy  INSTRUMENTS USED   PLANE TABLE  • The board IS made of well-seasoned wood such as pine or teak  • Size : 75 x 60, 60 x 45 cm  i. Simple plane table : tripod  ii. Johnson's plane table : ball and socket iii. Coast survey plane table : foot screws  ALIDADE  • The alidade consists ofa metal (brass or gunmetal) or boxwood straight edge  • 50 cm length  • The bevelled (ruling or working) edge of the alidade is called the fiducial edge  i. Plane alidade : has only eye vane , object vane . Only plane  ii. Telescopic alidade : has a telescope. Can rotate about the horizontal axis   PLUM BOB, PLUMBING FORK  • U shaped metal frame with upper horizontal arm lower inclined arm  • Plum bob hangs...

A traverse survey is the frame work consists of a series of connected lines, the lengths and directions of which are measured with chain or a tape and with an angular measuring instrument respectively.  I. Closed traverse : A traverse is said to be closed when it returns to the starting point forming a closed polygon. E.g. plot  II. unclosed or open traverse : A traverse is said to be an open traverse when it does not return to the starting point. E.g.. Road, river, railway METHODS OF TRAVERSING  1. BY THE CHAIN ANGLES: -  • Linear measurements are taken  • Angles fixed by the lateral measurements are known as chain angles.  2. COMPASS TRAVERSING /FREE NEEDLE/ LOOSE NEEDLE METHOD  • Angles are measured by compass and length measured by chain • In this method an angular measuring instrument, is set up at each of the successive stations and the bearing of each line is taken with reference to the magnetic meridian.  • In this system the errors are n...

• The compass does not measure the angle directly, but measures magnetic bearings only  • Relatively low accuracy  • Used area to be surveyed large , fast surveying SYSTEMS OF ANGULAR MEASUREMENTS SEXAGESIMAL SYSTEM  1 circumference : 360*  1 degree : 60 min  1 minute : 60 sec  CENTESIONAL SYSTEM  1 circumference : 400 grade  1 grade : 100 centigrade  1 centigrade : 100 cent centigrade  HOURLY SYSTEM  1 circumference : 24 hrs  1 hour : 60 min  1 minute : 60 sec  CIRCULAR SYSTEM  1 circumference : 2pi radian SYSTEMS OF BEARING WHOLE CIRCLE BEARING  • The bearing of a line is measured from the reference meridian towards the line right round the circle  • Value between 0 - 360*  • The bearings observed in a prismatic compass or a theodolite is the whole circle bearings.  REDUCED BEARING / QUADRANTAL BEARING •Bearing is observed clockwise or anticlockwise from north or south whichever is the close...

CHAIN SURVEY •Mainly used in surveying small flat ground  INSTRUMENTS USED IN CHAIN SURVEYING  I.   CHAIN  II.   TAPE  III.  RANGING ROD  IV.  RANGING POLE  V.  ARROWS  VI.  PEG  VII.  CROSS STAFF  VIII.  PLUMBOB  IX.  OFFSET ROD  X.  LATHES AND WHITES 1.  CHAIN •Made of galvanized mild steel wires of 4mm thick  •2 brass handles connected to chain with swivel joint – to prevent twisting ( bolt used : eye bolt )  •Groove is provided at the outer edge for holding arrows. Measurements are taken between the outer edges  •Degree of accuracy is 1 in 1000  TYPES OF CHAIN I.METRIC CHAINS •Available in 5,10,20,30  •1 link – 20 cm  •Brass rings in each 1 meter  •Tallies in each 5 meter TOLLERANCE PERMITTED  1m ± 2mm 5m ± 3mm 20m ± 5mm 30m ± 8mm PERMISSIBLE ERROR Rough / hilly – 1 in 250 Average ground – 1 in 500 Level ground – 1 in 1000 NO...

SURVEYING : •Process of determining relative position of a point PRINCIPLES OF SURVEYING •Location of a point from 2 points of reference •Working from whole to part PRIMARY CLASSIFICATION OF SURVEYING  I.Plane survey •Curvature of earth is not considered •Level lines – straight , plumb lines – parallel •Area to be measured <260 km2 •Area divided into triangles – plane triangles II.Geodetic survey •Curvature of earth is considered •Area to be measured >260 km2 •It is also known as Trigonometrical survey •The difference in length between the Geodetic survey and the plane survey, for measuring 18.2 km, is only 10 cm CLASSIFICATION OF SURVEY BASED ON FIELD OF SURVEY I.LAND SURVEY •Topographical survey •City survey •Cadastral survey II.MARINE / HYDROGRAPHIC SURVEY III.ASTRONAMICAL SURVEY BASED ON PURPOUSE OF SURVEY I.ENGINEERING SURVEY II.MINE SURVEY III.ARCHEOLOGICAL SURVEY IV.MILLITARY SURVEY V.GEOLOGYCAL SURVEY BASED ON INSTRUMENT USED I.CHAIN SURVEY II.THEODOLITE S...