Establishment of a geodetic network for deformation monitoring of the third mainland bridge, Lagos Nigeria

Abstract

There have been several cases of bridge collapse all over the world leading to loss of lives and valuable infrastructure. Such incidents can be averted if bridges are properly monitored through deformation surveys. This study aims at establishing a geodetic network for deformation monitoring of the Third Mainland Bridge in Lagos State, Nigeria. High precision Global Navigation Satellite System (GNSS) surveys were deployed for the observation. Points in the network were established by simultaneous redundant observation from three existing first order controls (XST series) in static mode. The raw field data was subjected to least squares adjustment and the redundant observations were reduced to give the three-dimensional (3D) coordinates of the points that make up the network. With this network in place, the positional integrity of the bridge can be continuously monitored.