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D-bridge is the patent of Grert Wall.It was invited fom Gemany and
has advantage in the long -span and big loading comparing to balley
bridge.Thus, it can save cost of piers.
It panel chord is bigger than bailey bridge panel but the panel
structure is simpler .All the components are bolted so the bridge
can be used as a permanent bridge because of its small deflection.
The components are inter changeable and repetitively used.This kind
of bridge has various
structure changes to satisty diferent loading capacity.