Designing issues of the geodetic vertical reference network of Lithuania

Abstract

Activities of Lithuanian National Geodetic Vertical Reference Network (NGVRN) establishment are going on since 1998. The goal of NGVRN establishment is a creation of new Lithuanian height reference suitable for present period practical and scientific needs. The Lithuanian Geodetic Vertical First Order Network consists of five polygons. Perimeter of the network is ca. 1900 km. Its development was finished in 2006. Connections of the first order vertical network with the vertical networks of neighbouring countries were established. All this creates good preconditions for determination of relations between height systems and for introduction of a new Lithuanian geodetic vertical (height) system. But this network is not dense enough to transfer the geodetic vertical system to the all territory of Lithuania and to improve the geoid model. It is necessary to dense available First Order Geodetic Vertical Network by developing the Second Order Geodetic Vertical Network. The territory of Lithuania is divided into five regions. Borders of the regions are First Order Network levelling lines and lines connecting Lithuanian national Vertical Network to the corresponding networks of the neighbouring countries. The regions are called: South, East, North, West and Centre. The design of the Second Order Geodetic Vertical Network is presented. The necessary density, accuracy of the geopotential numbers and ellipsoidal heights are discussed. Some results of the geodetic measurements are presented too.