The Iztueta Viaduct was built in 1944 and crosses the Madrid-Irun railway, thereby linking downtown San Sebastian with the city´s Egía neighborhood. Several weeks ago, the viaduct was closed to traffic in order to commence its demolition and remaking as an underpass. Stemming from community input gathered during a public engagement process carried out by the Donostia city government, this project will improve traffic patterns as well as enhance pedestrian access in the area. Demolition of the existing viaduct structure constitutes a preliminary step in the construction of a new roadbed that will pass beneath the railroad tracks. The new underpass will maintain the cross section dimensions of the current viaduct roadway. Following completion of the new underpass, railroad traffic will be carried by a new steel through girder bridge. Visual integration of the new bridge with the existing adjacent truss bridge is realized by setting girder top flanges at the elevation of the existing truss bottom chords. Furthermore, the girder webs feature triangular plates arranged at angles to the conventional web plane, creating an allusion to the scale and rhythm of the existing truss diagonals. This arrangement also favors an improved web buckling resistance, allowing for thinner web plates. FHECOR Ingenieros Consultores developed the Iztueta Viaduct demolition project and designed the new railroad bridge.