Precise leveling network analysis by graphic chart

Abstract

Relative measurements made between any pair of Benchmarks (PB1 and PB2) in a precise leveling network often involves at least one forward and one backward observation in a PB1→PB2, PB2→PB1 sequence respectively. However, due to fatigue on the part of the surveyors and field assistants, hazards along geodetic survey routes and some times attempt to reduce financial cost of field surveys, observations made in one direction and are assumed to be adequate for both ties (fore and back).This is a technical bias or constraint imposed on the network, which will surely result in a weak, poor and deficient control of measurements in the network. To ensure completeness and geometrical strength and reliability in a survey network, analysis by graphic chart is relevant. This paper used graphic chart technique to analyse and evaluate the completeness, homogeneity and symmetry of a precise leveling network over part of Samaru Campus of Ahmadu Bello University, Zaria. The results show about 62% completeness, absolute homogeneity (H=0) and absolute symmetry (100%). It is recommended that network analysis for all precise leveling networks be carried out prior the rigorous adjustment computations in order to detect any missing links and ties in the network and to improve the network reliability and accuracy. Engineering and applied science problems that require a two-way measurement or feedback system could benefit tremendously from this technique.

Keywords: Precise leveling, network, graphic chart, analysis