For more than 1 year, workers had to claim land from the estuary of the Seine river and struggle against tides, and the mud and silt, to find the necessary space to build the foundations of the piers for the Towers, and the ramps leading from the shore up to the bridge. More than 750.000 tonnes of earth and rock were moved in an uniterrupted round of trucks which took over 15 to 20.000 trips to bring the material to make the ground foundations.