How do bridge contests score entries?
Efficiency, load only, specific strength, longest span, lowest mass: the scoring systems student bridge contests use and what each means for your design.
Updated · 1 min read
Short answer: most rank by load held divided by the bridge's own mass, but some rank by load alone, by the longest span, or by the lightest bridge that reaches a set load. Read the scoring section first, because it changes what you should build.
Common systems
| Scoring | What wins | What to build |
|---|---|---|
| Efficiency (load ÷ mass) | Best ratio | Light and strong |
| Specific strength (maximum load ÷ own weight) | The same idea under another name | Light and strong |
| Load only | Highest load | As strong as the mass limit allows |
| Load cap, then lowest mass | Lightest bridge that reaches the cap | Just strong enough, very light |
| Longest span | Greatest gap crossed | A design that stretches, often with supplied sticks |
| Time or tie-breaks | Fastest build, or smallest mass, when scores tie | Practice a repeatable build |
Other things that can count
- A design report, an interview or a prediction of the failure load.
- Penalties for breaking a rule, such as being over the mass limit or leaving too little clear space.
- A minimum load the bridge must hold at all, before it is ranked.
Why it matters
A bridge built for efficiency is the wrong bridge for a load-only contest, and the other way round. Decide which kind of contest you are in, then design for that. See the efficiency score and what specific strength means.