Stange Overpass is a two-span railway reinforced concrete bridge on the Dovre line that connects the cities of Oslo and Trondheim in Norway. It was extended by 1,5 meters in each direction in 2004. During the extension, the part of the deck that has been extended from the abutments had not been placed on a foundation but, instead, had directly been constructed over the soil mass. Within the context of the Intercity project that has recently been undertaken by BaneNOR, passenger trains that cross Stange Overpass will be upgraded to high-speed trains. For this, the existing bridge needs to be evaluated for the new train type. This requires a finite element model that correctly and reliably models the dynamic behavior of the bridge under various environmental and loading conditions. Preliminary analysis results show that the most significant parameter that governs the dynamic behavior of the bridge is the load-deformation behavior of the soil that directly supports the ends of the deck that extends outwards from the abutments. Further, the load-deformation behavior of the soil can be expected to be highly sensitive to the environmental conditions and the changes in these conditions from summer to Nordic winter. To provide a reliable estimate of the load-deformation behavior of soil as well as a reliable finite element model, an instrumentation set-up will be installed in the bridge by Oslo Metropolitan University in collaboration with BaneNOR. A new finite element model updating algorithm will be developed that can not only estimate the traditional linear parameters but also the non-linear force-deformation relationship of the soil mass underneath the bridge deck. This article provides a summary of the initial stages of the project including preliminary acceleration measurements in the bridge, sensitivity analysis that has been conducted to quantify the effects of the soil model on the bridge behavior and optimization of the instrumentation set-up.