what determines the distancea beam bridge can span
Beam bridge Beam bridges are often only used for relatively short distances because, unlike truss bridges, they have no built in supports. The only supports are provided by piers. The farther apart its supports, the weaker a beam bridge gets. As a result, beam bridges rarely span more than 250 feet (80Â m). This doesn't mean beam bridges aren't used to cross great distances, it only means that a series of beam bridges must be joined together, creating what's known as a continuous span.
Golden Gate Bridge The Frommer's travel guide describes the Golden Gate Bridge as "possibly the most beautiful, certainly the most photographed, bridge in the world."[8][9] At the time of its opening in 1937, it was both the longest and the tallest suspension bridge in the world, with a main span of 4,200 feet (1,280 m) and a total height of 746 feet (227 m).