Soraluze is located in a valley through which the Deba River flows. The riverbed is heavily altered within the municipal urban core, having been channelled for most of its course by riverbank retaining walls or by the façades of the buildings themselves, which are situated at a very short distance—sometimes with no setback from the embankment. At Gabolats Street, a bridge allowed crossing between both banks, connecting Gabolats Street with Baltegieta Street and accommodating both vehicular and pedestrian traffic. The bridge featured a single lane and consisted of three spans of deep reinforced concrete beams.
In general, the reach of the Deba River through Soraluze is obstructed by various structures located within the channel (up to six bridges and footbridges connecting both banks, including the Gabolats bridge). This results in flooding of a large portion of the areas and streets surrounding the bridge during 10-year return period flood events. Consequently, a comprehensive river intervention was proposed, involving the removal of existing weirs and, most notably, the replacement of the Gabolats bridge with a new structure designed to minimize hydraulic interaction with the river channel.
After conducting the relevant preliminary studies and assessing the primary constraints, a solution was adopted featuring a curved, variable-depth Warren-type steel truss above a single 37.0-meter span deck. The cross-section is asymmetrical, separating vehicular and pedestrian traffic by the truss itself. The vehicular lane is located on one side of the truss, while the sidewalk is on the other. The lane is 3 m wide and the sidewalk 2 m wide; factoring in the thickness of the structure itself, a total width of 6.2 m is achieved. Additionally, the depth of the bottom chord is set at 0.9 m below road level, an improvement over the current situation. Cantilevers extend from the bottom chord of the truss on each side to support the deck. These cantilevers are spaced 2 m apart and provide different overhang distances on either side of the main truss line.
