East Central High School Footbridge

Hello, my name is Jason Lee and I’m a high school senior in Mississippi. My bridge project is based on replacing and improving an existing bridge on my school’s campus to make it safer and more accessible. At my school, the main student parking lot is located between the school building and the football stadium and is used for both. When the parking lot was laid out, the handicapped parking spaces were located near the handicapped entrance to the stadium. Except for a single space near the front doors, these are the only designated spaces in the lot for the less abled. There is a large ditch that runs across the middle of the parking lot, between the handicapped spots and the school building. Without being able to cross this ditch, the only option would be a long walk around it. The school had a local craftsman build a wooden bridge several years ago. Unfortunately, its design and placement make it difficult to use by people in wheelchairs and those using crutches and/or walkers. The walking surface is narrow, uneven, and slippery when it gets wet. On top of this, the approach and departure angles on the ends are far too steep. To make the school more accessible to those with injuries and/or disabilities, I propose to replace the existing wooden bridge with a new aluminum bridge that meets ADA requirements for size, surface, and design.

The parking lot already has designated crosswalk areas marked so the bridge will be placed to line up with these. I took a series of measurements using a laser level to collect the elevation data across the ditch. One side of the ditch is approximately 16” lower than the other so the bridge will include an asymmetric design to account for this. Between both sides of the parking lot, the ditch just over 39ft long, so the bridge would have to be slightly longer than 39ft.

The bridge structure will be similar to a parallel-chord, Pratt or Warren style arched truss bridge. This will span the entire ditch without the need for a center pier for support. It will be anchored to concrete abutments on each end that will hold it in place but allow for movement due to temperature dependent expansion and contraction and normal use. I have included a picture of both a Pratt and Warren style bridge above.

The deck will be made of textured, perforated, aluminum panels bolted to the substructure. They will provide a rigid, non-slip surface but will be replaceable to allow for needed repairs and maintenance due to normal wear and tear. The mascot for my school is a hornet and I wanted to incorporate hornet-related elements into my design.  The area between the bottom chord and the deck will be filled with panels made of a series of hexagons. These represent the shape of the individual cells inside of a hornet’s nest.  The panels between the railing panels will include a series of cutouts to mimic the venation patterns found in hornet wings.  Additionally, these cutouts will allow air to blow freely through the structure, reducing the load on the bridge during high-wind events which are common near the Gulf Coast.

With the help of my IT teacher, I was able to 3D print the After cleaning off the supports and making some modifications to the physical bridge model, I primed and painted it with a metallic spray paint to mimic the aluminum color. To better show the scale of the bridge and our school's parking lot, I found an STL model of my car, a 2006 Toyota Highlander, and had that printed as well. I then primed, painted, and put together the physical car model. This had many steps as I used a can of touch up paint for the base color of the car. I then used a liquid chrome pen for the headlights and painted on the other details like the windows, wheels, tires, and brake lights.

For this step, I will be discussing all that went into creating the 1/48 scale diorama of our school's parking lot. To create the parking lot I used the measurements from the start of the project to create the ditch that the bridge would be crossing. I used various materials obtained from our local hobby shop such as scale parking spots, fake grass, paints, 1 by 2 birch wood, and wood stain. The parking lot is 13.5in x 16.5in, making it equivalent to 54ft x 66ft at 1/48 scale.

Finally, after creating the land for the diorama and doing the finishing touches on the 3D printed models, I created the final product. This diorama includes the bridge with elevation difference of our school's parking lot, a replica of my vehicle, a replica light pole, realistic parking spots, and even a small stream at the bottom of the ditch.

Since the bridge is located in an area that is free from overhanging trees or structures, it makes an ideal location for collecting environmental data. Wireless weather instruments will be mounted to the bridge and will be powered by solar panels. These panels will also power LED lighting under the deck to provide illumination at night. Sensors along the bridge will also collect solar irradiance data for an upcoming solar energy project.

Through doing the "Make It Bridge" contest I have learned a great deal of things from 3D modeling to staining wood. In the end, this is a STEM project and part of that is making mistakes and learning from them, which I have done a lot over the past couple of months. One such mistake was this print, which was majorly damaged after the temperature changed during the print. Another mistake I made was trying to paint with a bristle brush, which resulted in a worse quality paint job on the car. I fixed this by using a sponge brush to repaint the sections that I was unhappy with. All in all, this project was a great use of my time and resources and I learned special skills that I will take with me into the rest of my life.