The Lusitania Bridge was designed to supplement a 2000 year old Roman bridge, the La Akazaba.  The La Akazaba had been relegated to foot traffic only, so a new bridge was needed to handle both motor & foot traffic.

The arch of the bridge lies between the two roadways, supporting them centrally.  The weight of the dual roadways balances the structure, with the pedestrian pathway lying along the central support girder.