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ABSTRACT The road tunnel, which will connect Gdynia-Sopot-Gda'nsk agglomeration to its ring road, will run through moraine heights composed of glacial deposits. Because of the need to protect landscape, the tunnel, running at a quite shallow depth, has to be constructed using mining methods.A detailed technology of mining works might be determined on the base of geotechnical recognition of the area of the planned investment. Because of expected complex geotechnical conditions along the tunnel route, traditional geological and geotechnical investigations are supplemented with geophysical investigations performed with use of seismic and geoelectric methods. The geophysical investigations will make it possible (basing on differentiation of physical parameters of subsurface medium), delineating of geological structures in subsurface and interpolate reliably point information gathered in wells along the whole route of planned tunnel. In the paper an example of results of geophysical investigations and geotechnical cross-section elaborated on the base of geophysical, geological and geotechnical data along a selected section of the planned tunnel are presented. The results of conducted works have shown the geophysical investigations are very useful in recognition of geological structures tested and distribution of geotechnical parameters within them. 1 INTRODUCTION The road tunnel planned in Sopot will connect the metropolitan area Gda'nsk-Gdynia-Sopot to the ring-road located around the whole agglomeration. The main goal of investment is to decrease traffic in centre of the agglomeration. The tunnel of length 1350m and diameter 6m will intersect, at depth up to 46 m, a streak of moraine heights located within the Three- Cities Landscape Park. Because this is a protected area, where the tunnel is planned, no destructive works (on the surface) are allowed there. So, the tunnel has to be constructed using mining methods. Technology of mining works will depend on geotechnical conditions detected along the tunnel route. 2 CHARACTERISATION OF THE SITE AND ITS GEOLOGICAL STRUCTURE The tunnel will be located at border area of Gda'nsk- Wejherowo Height which origin refers to accumulation and erosion activities of Baltic glaciations. Up to depth 30–60 m, ground consists of glacial-tectonic disturbed Pleistocene fluvial-glacial sands and boulder clays. Pleistocene fine and medium sands change in eastern part into unsorted material and gravels with boulders. Sand layers are separated by a boulder clay horizon which consists of clayey sands and sandy clays and glacial lake sediments consisted of silty clays, silts and mud. 3 GEOPHYSICAL INVESTIGATIONS Diverse sediments where the tunnel is to be driven are characterized by variable permeability, mechanical properties and also physical parameters, which are measured as a result of geophysical surveys. Impermeable sediments (clayey silt) are characterized by low values of electric resistivity and permeable sandy-gravel sediments by high ones. Mechanical properties of the subsurface sediments are strictly related to velocity of seismic waves propagating within them. So, in geophysical investigations, methods based on measurements of electric resistivity "ρ" and seismic wave velocities "Vp" have been applied in order to delineate distribution of these parameters in the studied subsurface sediments.