1. Materials used in the construction of the bridge shall consist only of commercially available rectangular balsa stock and glue.

2. The total mass of the bridge plus glue must not exceed 100.0 g.

3. The bridge shall contain no element wider than 1.0 cm (3/8 ") nor thicker than 0.65 cm (1/4 ") Two or more elements, each separately meeting this requirement, may be laminated together to construct members exceeding these dimensions.

4. The bridge shall allow a 5.0 cm cube to pass underneath without touching the structure. The bridge shall also allow a 40.0 cm long by 2.0 cm high board to slide underneath without touching the structure.

5. The bridge shall be "free standing".

6. An approximately level, smooth roadway surface, of minimum length 40.0 cm and above the 5.0 cm mark, shall be provided, across which a small metal car (e.g. Matchbox, Hot Wheels) will roll when given a single light push of the hand. This roadway shall have a minimum width of 5.0 cm and shall allow a 5.0cm cube to pass freely along its extent. Note: the roadway materials must conform to rule (3).

7. No fastening mechanism except mechanical interlock of the balsa pieces or commercial glue is permitted.

8. The bridge design shall allow the standard test frame to be placed on the roadway surface with the load support rod(s) extending beyond the bridge sides.