The double-decker Luís I Bridge spans the River Douro between the cities of Porto and Vila Nova de Gaia in northern Portugal. The bridge – completed in 1886 and built next to an adjacent bridge it replaced – consists of complex ironworks with a great arch and spans 172 meters (564ft) and a height of 44.6 meters (146ft). The two levels had been designed to carry road traffic up to 2003, but today is used to carry the Porto Metro light rail on the upper level and a pedestrian walkway and road traffic beneath.
In 2003-2004 the bridge underwent a major refurbishment, including steel re-inforcement to allow the installation of the light rail on its upper deck. During this work, the steel bridge was fully blasted to bare metal and coated with a zinc-free coating system consisting of two coats of epoxy and one coat of polyurethane finish, with a total of 290 microns dry film thickness. Sherwin-Williams’ Dura-Plate 301 ultra-tolerant epoxy technology was used.