The Oporto São João Railway Bridge – major design improvements through experimental tests

In the early 1980’s the Portuguese Government considered the possibility of replacing the aging 1877 Maria Pia railway bridge. Due to traffic constraints in the Portuguese north-south communications network a new bridge was necessary. A major competition was organized for a new railway bridge to improve the rail traffic between the twin cities of Oporto (north bank) and Gaia (south bank), where a larger traffic velocity (120km/h), higher axle loads and improved safety regarding derailment was required. This new innovative structural concrete bridge, with a strong aesthetic impact, had to use the existing network tracks but major adaptations had to be made on a 4km extension from Gaia to Oporto. The experimental tests carried out on the site laboratory were critical to guarantee a long lasting durable solution.