TOPOGRAPHICAL SURVEYING INTRODUCTION A topographical survey aims to determine the relative locations of points on the earth’s surface bymeasuring horizontal distances and vertical differences in elevation. That is (X, Y and Z). Thetopographical maps produced often give the locations of places of observable features within thestudy area and information about elevation changes depicted using spot heights and contours. Thetopographical and cadastral maps serve as base maps. Surveying Topographical surveying determining the relative locations of points (places) on the earth's surface by measuring horizontaldistances, differences in elevation and directions Applicatiopns of topographical survey ❖producing topographic maps ❖constructing topographic (cross-sectional) profiles ❖establishing vertical and horizontal control for accurately defining locations ❖A topographical survey should be used before construction begins to ensure the proposeddesign will work in these conditions. ❖Governmental agencies also make use of topographical surveys when making and enforcingconstruction and zoning regulations, evaluating existing infrastructure and needed revisions,and when considering environmental projects. J. OMEKE 2021 EECQ 2233 ENG. SURVEYING B 1
❖Topographical surveys are also used to make maps used in industries such as geology,petroleum, and forestry. ❖Engineers need a topographical survey to see the elevation of the land’s surface and todetermine if there is a need to bring in or remove dirt in order to adjust the grade of theproperty. ❖Architects might use the survey to create a 3D plot of their design for a construction project. This plot can be presented to decision makers for approval prior to groundbreaking. 1. OBJECTIVES OF TOPOGRAPHICAL SURVEY 1.1 Objectives ❖To measure changes in elevation between different locations of the project area. ❖To produce the topographical-cadastral maps of the project area using collected data; ❖To map topographic features and generate topographical maps and cross-sectional profiles; ❖To establish horizontal and vertical control points using Ordinary Ground Levels (OGLs) liketraversing and leveling methods; ❖To carry out a detailed topographical survey by collecting (X, Y, and Z) of topo features andspot heights. ❖To establish the controls for accurately defining locations within project areas and productionof contours. 1.2 Procedure ❖Selection of a scale: Depends on the extent of the project area; this determines the plottableerror. ❖The working principle for a topographical survey is to work from the most accurate to the leastaccurate methods with minimal errors. ❖The orientation of each survey must be and preferably concerning the True North (N).