I am in a high school Precalculus class. We are about to have a project where we build bridges with PVC and twine. The goal is to hold as much weight as possible. For this project, I believe we will be given 28 feet of PVC, a roll of twine, and 5 or 6 days to design and construct our bridges. Also, I think we are designing arch bridges, where there is a main part and a parabola rising above it on each side. Another constraint to the design is that the main portion has to be a certain, so far unstated length in order to reach two blocks so that it can be loaded with weight. All that said, the purpose in this thread was to receive input from the experts that frequent this website. My teacher told us to do as much research as possible, so I am asking you as well as searching for online resources regarding bridge building. Thanks in advance for your responses.