Protractile Triumvirate

Developments and Modifications:

To advance our previous study model, and to prepare for final presentation, we decided to make a few minor modifications to our design in order for it to perform better. A few modifications were:

  1. Making the joints thinner in width (.25″)
  2. Adding a third hole to all the joints, in order for the locking pieces
  3. Making all the pieces thicker for added stability (.5″)
  4. Creating exact width spacers compared to joint width (.25″)
  5. Changing screw sizes 
  6. Slightly changing length of bottom scissor pieces (13.36″)
  7. Adding washers

With these modifications we believed that the bridge would function even better, and more smoothly. By creating the thicker, more exact, scissor pieces we ensured that the bridge would expand and collapse evenly without any variations in length or height. By modifying our existing joints to be thinner we achieved an even more compact design that worked better with the created spacers.

The name Protractile Triumvirate comes from the overall concept of the model. The bridge protracts in a single linear motions using three unionized scissor structures, thus making it a triumvirate. We felt that highlighting the three separate scissors in the name was crucial because they are the main, and only, driving fore behind the motion of the bridge. 

Producing all these final adjustments we were ready to assemble the final mode, create step by step drawings, technical drawings, and animations, of our work. 


Final Model:


Shown above and below is the final working model. Included in this model is all the modifications mentioned above. Compared to previous models this model was more precise and allowed for the bridge the collapse easier and thinner. The new joints and spacers worked in unison to create a fluid plane that all the scissors expand and contract on.

One major issue with this final model though was painting the pieces, and how the paint effected the movement of the scissors. The paint made the joints and rotations stiff and sticky, making it harder to operate the bridge. Also the thin layer of paint made it almost impossible to install the paint, due to the fact that the cuts and spacing’s were so exact. But after opening and closing the bridge repeatedly the paint began to wear were rotations were taking place, making the model much more fluid. 

The final model turned out to be very clean and an elegant looking model/sculpture. This was consistent with our goal for the project; to create a simple, lightweight, and strong bridge that has minimal parts and moving pieces. With a repetitive assembly process and design, the final bridge is designed to be carried in scissor modules by an individual. 


Animations and Renders:

To show the full assembly process, and the ease of it, renders and animations were created. These animations show the process one would go through to assemble the entire bridge in three steps. These three steps include assembling the bottom scissors, assembling the side scissors, and lastly connecting the two to the bottom and top joints. The video then transitions in to showing the expansion process of the bridge in different segments. 

The effectiveness of these short and simple renders truly proves and explains how simple the process is, and how simple and practical the bridge is a whole. 




The renders shown below highlight the elegance of the bridge in full deployment, as well as it fully exploded to show all the pieces. Rendering of a design like this contribute to the project by showcasing individual connections in detail, as well as the entirety of the form in high quality. 

By having the renders very similar to our physical model in terms of color design and craftsmanship it was a great comparison between the two for the reviewers.  It proved that a computer generated model could thus be easily be applied and created in reality, supporting our goal to create a practical bridge from simple parts. 


In Conclusion and Improvements:

The Protractile Triumvirate is a versatile bridge that incorporates the use of three scissor structures and two joint variations to create a structure that is easily deployable and strong. Working in unison; the three scissors provide the central support to the two parallel walkways connected to each side.

With a total deployable length of at least 16 feet, the Protractile Triumvirate can adjust to various crossing distances through variations in the length of the scissors. When fully collapsed the structure is 4’ in width and 4’ in length, making it easy to carry and transport to another location. But is disassembly is required, the assembly process is straightforward and repetitive, and needs only two tools and five separate parts.

In reality we would like to further better this design by creating the scissors with metal telescoping rods in order to provide another degree of compatibility and strength. Another thing we would like to improve on is the design of the pathway. By having the pathway expand and collapse with the overall structure as it expands and contracts would make the bridge an even better uniform structure, and provide more versatility. 


This project was a create learning experience in many ways that exposed us to new structures, forms of thinking, and new methods of fabrications. While tackling all these new challenges we believe that we have produced and constructed the most applicable bridge for the scenario, and a bridge that has many more possibilities through more research and development in the future. 

– – Will Hachtman & Byron Campos

Poster template_Bridge






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