structure remain the flattest to have ever been constructed. History Background During the 1830s, the famed mechanical and civil engineer Isambard Kingdom Brunel developed a plan for a railway running on an east–west alignment in between the key cities of London and Bristol. The line, which would become known as the Great Western Railway, would feature exceptional attention to maintaining either level ground or gentle gradients of no greater than 1 in 1000 through the majority of the route. A key crossing of the envisioned railway occurred between Maidenhead, Berkshire and Taplow, Buckinghamshire, where the line would cross over the River Thames; Brunel himself undertook the design for this structure. The building of a bridge over the Thames at this location had to make provisions for the necessary navigational clearance as not to unduly hinder the traditional river shipping present. However, this clearance requirement, when combined with Brunel's desire to maintaining a gentle gradient of 1 in 1,320 for the railway lines, posed some complication to the bridge's design. There was a strong distaste for any compromise upon the gradient which had been set out for the whole route as he believed that this would negatively affect both passenger comfort and the maximum speeds of the trains that could otherwise have been avoided. The first plan devised by Brunel for the river crossing had envisaged the building of triple-arch viaduct at the site, however he later chose to discard this early concept in favour of the design that was subsequently built and is still in use today. According to author Paul Clements, the design selected by Brunel had been directly inspired by earlier experiments performed by his father, Marc Brunel, during 1832, which Isambard had at the time financed. Brunel employed calculus principles in the designing of the bridge's critical semi-elliptical arches, which supported the structure. In common with the design of the other large bridges that were built along the line, Brunel achieved a reduction in the forces acting through the brickwork via the adoption of internal longitudinal walls and voids; these served to lighten the superstructure above the arches as well as to reduce the bridge's overall weight. As designed, the bridge carries the railway across the river on a deck supported by a pair of elliptical brick arches which, at the time of their construction, were the widest and flattest in the world. Each arch has a