Road Bridge across the Uruguay River

The Santo Tomé - Sao Borja road bridge between Argentina and Brazil over the Uruguay River has two vehicle lanes and two pedestrian walkways. It consists of 33 simply supported spans of 42.50 m. The superstructure, formed by three precast post-tensioned U-shaped girders and cast-in-place concrete deck slab, is supported by planar portal-frame piers made of two piles embedded into the sound basalt foundation. The piles of the central 18 spans were built with steel casings from a barge moored in the river. The river has a flow of about 2.5 m/s and a water depth of 10 m. Because it is difficult to perforate the foundation rock under such conditions, static and dynamic tests were performed during and after the completion of construction. These tests assessed the effectiveness of the provisions adopted during the design stage in order to keep horizontal displacements along the bridge axis within acceptable values.