Although the UK Libraries have hundreds of eBooks accessible and searchable via InfoKat Discovery, here is a direct link to an eBook collection that has materials useful for civil engineers.
Walnut Lane Bridge, Philadelphia, Historic American Engineering Record (HAER) photo. This documentary photo, taken in 1968, shows the Walnut Lane Bridge span, comprised of a parallel series of prestressed, post-tensioned concrete beams, aligned closely together. Source: Library of Congress.