Hydraulic Balsa Wood Rising Bridge


Kaitlyn Greenfield

Faculty Mentor(s)

Charles Pringle (Mechanical Engineering Technology)


What is the solution to allowing tall vessels to navigate past a vehicle bridge that is less than 10 [ft] above the water? To answer this question, a balsa wood bridge was designed, constructed, and tested. The bridge needed to articulate by mechanical means, allow for travel through the bridge, and be able to withstand ample force while the main structure only being constructed of balsa wood and glue. The project was analyzed in sections. These sections include: the bridge structure and its members, the hydraulic lift, and the pins needed for the bridge and hydraulic lift to operate. The analysis determined that the bridge design would be suitable for the specified requirements. The requirements include: being able to hold 18.9-20 [kg], articulate to 140 [mm], hold the position for 5 seconds through mechanical means, weigh less than 85 [kg] without the articulation mechanism, span a gap of 400 [mm], and allow travel through the bridge without obstruction. Construction of the parts needed to build these sub-assemblies and assemblies was completed first. The bridge structure was then built in sections: the bridge structure sub-assembly, the hydraulic lift sub-assembly, and the bridge assembly. Once built, the balsa wood bridge was tested to make sure it met its objectives. These tests were conducted on an engineering basis, such as the concepts of bending stress, moments, and material properties. The series of tests conducted proved that the final design of the bridge would meet the requirements stated above.

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1 thought on “Hydraulic Balsa Wood Rising Bridge”

  1. Kaitlyn – you definitely meet “rockstar” status!!! I am so proud of you and shared this with all your teachers! I also saw that you landed an engineering position…no surprise!!! Keep making us proud!!!

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