Leonardo da Vinci’s

Transportable Bridge

Leonardo’s Transportable Bridge Poster Image Copyright Permissions Picture of Leonardo Da Vinci with Mona Lisa and Vitruvian Man is Microsoft Clipart, in public domain. Leonardo da Vinci’s drawing of the transportable bridge is a photographic reproduction of art already in

the public domain, hence is in the public domain. Photo of Leonardo’s Bridge built with paint stirrers used with permission from RAFT (www.raft.net).

This illustration shows a completed bridge built with the RAFT activity kit titled Leonardo’s Arched Bridge at http://www.raftstore.net/leonardos-bridge.

Diagrams that show how to build Leonardo’s bridge are original graphics by Trisha Bergthold and are hereby released into the public domain.

Some HistoryLeonardo da Vinci was born in 1452 in Florence, Italy. He was a painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist, and writer. In about 1480, Leonardo had the idea to build a bridge with just wooden beams and nothing else. That way the bridge could be easily taken apart, moved, and rebuilt.

Forces on BridgesBridge components are affected by

Compression (pushing) Tension (pulling) Torsion (twisting) Shear (forces acting at angles)

Which force most easily causes Leonardo’s Bridge to collapse?

Which force can Leonardo’s Bridge most readily withstand?

Building Leonardo’s Transportable Bridge

Start in the middle. Lay 5 sticks out as shown.

Lift up #1. Slide in two beams to go under #1 and rest on top of #5.

Lift up #2. Slide in two beams to go under #2 and rest on top of #5.

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Now you have a 9-beam Leonardo Bridge!Can you tell the Arch Beams from the Cross Beams?

You can make a longer bridge with a higher arch!

Slide a cross beam underneath the ends of #6 and #7.Slide a cross beam underneath the ends of #8 and #9.

Lift up #10. Slide in two beams to go under #10 and rest on top of #1.

Lift up #11. Slide in two beams to go under #11 and rest on top of #2.

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910 11

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915

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Now you have a 15-beam Leonardo Bridge!Can you keep going and build a 21-beam Leonardo Bridge?

Testing Leonardo’s Bridge

Test your bridge to see how much weight it will support.

Set a board across the top of the arch. Balance it with wedges between the arch beams and the corners of the board.

Load the bridge by placing weights on the board. Center the first weight precisely and gently add each new weight.

How much weight can your bridge support?

Estimating the Efficiency

of Leonardo’s BridgeThe efficiency of a bridge tells you how many blocks the bridge can support if each block weighs exactly as much as the bridge.

Estimate the efficiency of your bridge.

This bridge supports3 bridge-weight blocks.

Its efficiency is at least 3.

The same bridge falls under 4 bridge-weight blocks.

Its efficiency is less than 4.

Bridge = 175 grams

Bridge = 175 grams

Other Interesting Questions

What happens if you use sticks that are shorter than those you have already used?

What happens if you use sticks with square or circular cross sections and you whittle notches into them at the connecting points?