Minh LeFollow

Document Type

Undergraduate Project

Date of Degree Completion

Spring 2023

Degree Name

Bachelor of Science


Mechanical Engineering Technology

Committee Chair

Prof. Charles Pringle, Dr. John Choi

Second Committee Member

Prof. Charles Pringle, Dr. John Choi


This senior paper outlined the design and construction of an articulating balsa wood bridge. Meeting specific criteria to hold 20kg of weight hanging from the center of the bridge. Also allowing a 32 mm wide by 25 mm high object to traverse the road deck of the bridge. The construction criteria required the use of only balsa wood and glue for the structural support, with exceptions for articulation components. The total weight of the bridge must not exceed 85 grams.

To achieve these goals, the bridge was designed using static equilibrium and material strength equations to span a 470mm body of water. A 45mm wide solid balsa wood road deck ran the entire length of the bridge. A lifting tower was constructed to facilitate the required bridge articulation, with a string attached to one side of the bridge and a counterweight on the other side. The bridge's counterweight system provides efficient control for raising and lowering the bridge

The expected result was a functional articulating balsa wood bridge weighing 83 grams and capable of holding up to 24 kg before it failed. Several nondestructive tests were performed initially, followed by a final load-bearing test. The bridge was able to maintain its lifted position without any additional support for 15s. A block pulled with a string served as the vehicle, which could move unobstructed across the road deck.