Surveying

  Unit 4     Theodolite Traversing: 4.1 Traverse Definition, Purpose, Types and Equipment Traversing is that type of survey in which no. of connected survey lines form a framework and the direction or angle of survey lines are measured with an angle measurement instrument   like theodolite, total station and the length of the line are measured with tape or EDM (Electronic Distance Measurement). Theodolite traversing is a type of survey in which direction or angle of survey lines are measured with theodolite and length by tape. A traverse is a series of connected straight lines of known length, each joining two points on the ground and related to one another by known angles between the lines. Straight lines between the consecutive stations are traverse legs. And the points defining end of traverse lines are traverse station. There are two types of traverse: 1) Closed traverse a) Geometrically closed and b) Linked traverse 2) Open Traverse   1) Closed traverse A t

  3.1    Introduction and Uses of Theodolite:   INTRODUCTION   A theodolite is a precise instrument for measuring for horizontal angles, angles of elevation and depression i.e., vertical angle, bearing and azimuth of a line. Theodolite is also used for prolongation of survey lines, finding difference in elevation and setting out engineering works requires higher precision   i.e. ranging the highway and railway curves, aligning tunnels, etc. Uses of Theodolite a)    To measure horizontal angle accurately. b)    To measure vertical angle(zenithal angle) accurately. c)     To decide true north by astronomical observation. d)    To know the difference in elevation of two points. e)    To measure the height of tower, building and depth of a valley f)      To measure distance between two points. g)    For the alignment fixing of tunnel, road, railway, bridge, canal, etc. on the ground. 3.2    Geometry of theodolite: