english: And to do that meant creating the flattest gradients that had ever yet been made, which meant building long viaducts across river valleys -- this is actually the viaduct across the Thames at Maidenhead -- and long tunnels such as the one at Box, in Wiltshire.
non_english: Om dat te doen moest hij de vlakste hellingen ooit gemaakt creëren, en dat betekende lange viaducten door riviervalleien -- dit is het viaduct over de Thames bij Maidenhead -- en lange tunnels zoals die bij Box, in Wiltshire.