Midterm project in design problem solving last spring (04). This is a balsa wood bridge with a span of two feet. It is 3in wide at the center and 7.5 on the ends. The glue used was Elmers wood glue. It supported over 60 lbs before it sheared strait down the middle. I wanted to create a space frame stuctured bridge that was going to be as strong as a typical arch/strait beam bridge. 60lbs was the minimum for an A but i still think that the overall design could be improved given the time. The key features are that no single support member is made up of more that two peices of 1/8" balsa strips and that it is wider upon the ends. Overall this is a very good balsa bridge example.