The problem that we have is we need to find a bridge that will fill a gap that is 12" long, and 2.5" wide. Our objective is to build a bridge that can hold up to 2.5kg at the most. The bridge must have a length at least 3inches, and a width of 2.5inches.
Some constraints that we have are no more than 10% of the bridge may consist of "bulky" members made from two pieces of balsa wood. We can only use 15 pieces of balsa wood, and if we use string it has to be attached in a simple way. We could use toothpicks, but they can not be in a "bundle". The bridge must be self-supporting (so they can not be permanently attached to the table).
We have come up with three possible solutions that could work for this bridge project. Our first bridge that we came up with was a bridge that had one large truss that was connected by two solid vertical beams resting on a flat base.
The second bridge we designed was an arch bridge. On this bridge the arch will be placed on the bottom of a flat base. The flat base will be on top of the arch. And the arch will be connected to the base in the middle, and there will also be vertical beams on each end of the bridge between the arch and the flat base.
Our third bridge is a double arch bridge. The bridge has a flat base, and one arch on the bottom, and one on the top. This design is just like our second bridge, expect that this one has two arches that are connected to the base by vertical beams.
The bridge that we ended up choosing was our first bridge. We choose this bridge because it seems that it will not only be the easiest bridge to build but it also has a very strong design. We also liked the design of just one large truss, and thought the other bridges would be too hard to build with the materials that we have to use.