ローマン・コンクリート
The facing of the piers consists of local granite ashlar, set in parallel courses without the use of mortar or iron ties ("opus quadratum"); their interior, as those of the ramps, was filled with Roman concrete, a common method applied for Roman bridges. Outwardly, the flattened arches must have lent the bridge a rather elongated appearance, with its roadway following a horizontal or slightly convex line.