The safety factor

When Jean Rodolphe Perronet, Architect and Premier Engineer to the King of France, produced his design for the Pont de la Concorde shortly before the French Revolution, it was so advanced and exhibited such economy of line and materials that influential citizens sought to impose the condition that guards be placed at each end to slow down traffic. They maintained that the bridge would otherwise prove unequal to the task of sustaining eighteenth century loads. When the writer of this article, in 1959, crossed the roadway of this bridge he was firmly of the opinion that traffic accelerated towards him. The effect upon him was considerable, but the effect upon the bridge was no more than all other traffic in the intervening 180 years.