What is a trussed Girder bridge ?

Question

I would be greatfull if you could help x

Answer 1

A girder bridge is one in which a girder (huge i-beam roughly) is placed along side the roadway which is supported between the flanges of the beam.

A trussed Girder bridge constructs the beam out of smaller elements arranged in triangles - a truss - using less material but costing more to make.  

like this  (the arches being decorative, not structural)

http://www.istockphoto.com/file_thumbvie...