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.

1. The bridge pedestals shall be placed on level surfaces separated by approximately 35 cm. These surfaces shall be level with respect to each other.
2. The standard test frame will be placed on the roadway over the centre of the bridge span. Depending on the bridge design, the load applied to the bridge shall either be suspended from a single 1/2 " diameter rod placed in the centre slot of the test frame, or from two such rods placed in the outer slots. Where either option will work, the judge(s) shall decide on the method to be used.
3. A container shall be suspended from the load-supporting frame. To this container (which may be pre-weighted with steel weights as warranted in the opinion of the judge(s)), dry sand and/or steel weights shall be added at a slow, steady rate, until either an audible cracking sound together with visual evidence indicates the failure of some structural member or glue joint of the bridge, or until a suitable reference point on the roadway at the centre of the span has been lowered by more than 1.0 cm. A competitor may not participate in the addition of weight to his/her own bridge. All decisions of the judge(s) are final.
4. The total mass of the test frame, container, hanging devices and container contents shall be recorded as the competitor's score.
Standard Test Frame

Overall dimensions: 10.5 cm (length) x 5.0 cm (width) x 3.7 cm (height)

Axle-Axle separation: 6.0 cm

This contest is held for physics 11 and 12 students at Notre Dame Regional Secondary in Vancouver BC. External entries will be accepted on a case-by-case basis. Unless these entries are from students within reasonable travel time of the school they should be shipped to arrive no later than two weeks prior to the contest. Application for such entries by e-mail notice should be no later than January 31 of the contest year.

Copyright 1980-2015
Peter L. Vogel
Adapted from a contest booklet published ca. 1978 entitled "Physics Olympics"