Densification of second order levelling : a case study : Mellieħa

Abstract

Chapter 1: In this chapter some explanation of Precise Levelling is stated as precise levelling ·is an introduction to second order levelling which is the main subject in this report. Chapter 2: This chapter explains what has been organised within the vertical control section to be able to carry out the densification of second order bench marks, such as new equipment bought. It also explains the planning reconnaissance and the equipment used for second order levelling: The advantages of doing such an exercise with a digital level are also stated. The importance and method of record keeping is another topic in this chapter. Chapter 3: The procedure of how the job itself was done is explained. One of the links is explained thoroughly from the first primary bench mark to the intermediate bench marks and to another primary bench mark mentioning also difficulties that have been met with. Chapter 4: This is the chapter in which all the results derivations are shown. The values of the P.B.Ms quoted have been derived from the differences in heights between them as acquired from the Mapping Unit Surveyors. These have been found out by precise levelling. To arrive to the quoted values, one of the P.B.Ms has been given an Assumed value of 100.000 mts. The workings of the secondary bench marks values and the adjustments both by simple adjustment and by the Starlev Adjustment programme are shown. The differences occurring from both adjustments are also shown. Chapter 5: The sources of error are quoted in this chapter. These are the factors that have to be taken care of to perform the exercise of densification of bench marks.