Briggs Field Safety Fence (2023-2024)
Summer 2023, the MIT Archery Team obtained permission to practice on Briggs field for first time in its history. As Briggs field is a shared mixed use field, we needed to construct a fence to protect others on adjacent fields from crossing the range safety zone. This fence was designed and constructed by Lauren Chai and Elron Yellin.
Requirements: 400 ft long; assemble within 15 minutes by 4 people, diassemble under 15 minutes by 4 people; minimum height of 4 feet.
Design details: the 400 ft fence was broken in 100 ft sections. Key challenge is that the safety fence sags under its own weight. The sagging meant that the fence fell below the required 4 foot height unless posts were placed every 15-20 feet which was unfeasible for the required assembly time. The solution was to suspend the safety fencing on low-stretch paracord. The paracord was then suspended between the posts and secured at the ends on collapsible A frames. Space between posts is 35 feet. The weight of the fence led to excessive tension in the cord, which is solved by wrapping the cord around the posts. The capstan effect reduces tension, such that no additional weight is required at the A-frame to balance forces.
Construction Details: all wood ,held together with wood screws. Paint seals the wood against moisture. Posts break down into two parts - the tall ‘post’ and a cross-beam base that holds the post upright. A-frame lengs open/close about a hinge at the top. When opened, the frame base is limited by paracord.
Skills used: design (statics), woodworking (basic),