About Span
Span gives you a gap, a row of nodes and a limited number of beams. Join the nodes however you like, then send a rolling load across and watch what your design actually does.
Nothing about the failure is scripted. Every beam is a physical constraint with a breaking strain, so a bridge fails where the load genuinely concentrates — which is usually not where you expected. The lesson arrives on its own within about three attempts: a four-sided panel is a hinge, because it can change shape without any of its sides changing length, so the beams never resist until it has already folded. A triangle cannot deform without stretching a side, so it fights back immediately. Triangles are not a style. They are the only shape that carries load.
How to play
- Click one node, then another, to place a beam between them. Nodes more than one column apart cannot be joined.
- Click an existing beam to take it back and recover the material.
- The thick beams along the bottom row are the deck — the load rolls on those, so the deck must be continuous.
- Press space or the button to send the load across.
- Beams warm toward red as they approach their breaking strain, so you can see which member is about to go.
Five tips that actually move your score
- Triangulate everything. If you can see a four-sided panel anywhere in your bridge, it will fold. Adding one diagonal to it costs a single beam and is almost always the difference between a span that holds and one that does not.
- Build the deck first, then brace it. The load needs a continuous road or it falls through the first gap. Lay the bottom row, count what you have left, and spend it all on diagonals.
- Watch where the red appears, not where it breaks. The member that snaps is often not the weak one — it is the one that inherited the load after the real weak point started to give. The first thing to warm is the thing to reinforce.
- The middle carries the most. A load at midspan puts the deepest bending into the centre. If beams are tight, brace the middle third heavily and let the ends be plain.
- Under budget is a win, not a waste. Clearing a span with beams to spare means you understood it. The next gap is wider and you will want the practice more than the leftovers.
Frequently asked questions
Why does my flat bridge always sag and snap?
Because a row of beams with nothing above or below it forms a chain of four-sided panels, and a four-sided panel can change shape without changing any side length. The constraints do not resist until it has already folded. Add diagonals and the same number of beams will hold.
Is the breaking scripted?
No. Each beam is a distance constraint with a fractional strain threshold, and it snaps when it is genuinely stretched or squashed past it. The load pushes back on whatever it is standing on, so the strain distribution is real.
What happens when I clear a span?
The gap gets wider and your beam budget grows with it, but not quite as fast. Your score is how many spans you cleared.
Can I rebuild after a failure?
Yes. A failed span can be rebuilt from scratch as many times as you like — only the count of spans you actually cleared is recorded.
