Currently I am doing a straw building project with a group and we are in need of an interview from a real life engineer. So if anyone can help me with my design on our Girder Bridge then it would be appreciated.
I am not an engineer, and I see it may be to late, but depending on your materials and restrictions, I may suggest a truss bridge. If you double up the straws enough, the bridge should hold well enough. http://en.wikipedia.org/wiki/Truss_bridge" [Broken] is a link. Maybe search it on whichever search engine you use as well.