The following are the materials that can be employed in the construction of your bridge. Unacceptable construction is that of soaking or altering the material properties of the wood in any fashion. The bridge length shall be greater than 330 mm and less than 400 mm. The bridge must allow a tennis ball to roll end to end without falling off. You will need a guardrail.
Guardrails are safety requirements on most bridges.
The total mass of the bridge shall not exceed 150 grams. This allows the loading mechanism to be placed on the deck. The ends of the bridge shall lie flat on the testing supports, which are 330 mm apart. The bridge mass will be determined. A tennis ball will be rolled across the bridge from end to end.