This site is dedicated to the provision of information about and resources for balsa bridge building contests of the type run here at Notre Dame Regional Secondary School in Vancouver BC (Canada). Balsabridge.com and its precursor sites have operated on the World Wide Web since 1994.

Notre Dame's contests have been held annually since 1981. They involve all physics students in the school, that is those students taking either physics 11 or physics 12. Those who take both courses participate twice in the contest. The contests are quite straightforward in concept. Students build a bridge that meets various conditions and have it tested for maximum weight supported. These weights reach staggering values as exemplified by the current record holder.

In brief, legal entries must not exceed 100.0 g in total mass (balsa wood plus glue). They must span 40 cm and they must offer a clearance of 5.0 cm. They must include a roadway. Bridges must be produced from rectangular balsa stock, individual components of which cannot exceed the dimensions of the most commonly available "beam", the 3/8" by 1/4" stock (1.0 cm by 0.65 cm).

Testing of bridges is carried out through the addition of sand and various steel plates (weight lifting masses) to a steel garbage can that is supported through chains from a test frame placed on the bridge roadway.

Students entering the contest are encouraged to look at designs from previous years. This site offers several hundred photographs of balsa bridges. There is also a growing collection of photographs of actual bridges in the Vancouver area. Looking at photographs of real bridges can be a little disheartening for students as such bridges have different constraints or possibilities from those in the balsa bridge contest. For example, suspension bridges would not meet the rules of the contest in that they require supporting cables and large masses at the ends of those cables. Some arch bridges are difficult to duplicate in that they might require canyon walls or massive concrete towers to counter the outward thrust of the arches. In both of these cases materials beyond the balsa wood and glue limits would be required. 

Home