Moor Footbridge Redesign

Hello, my name is Will San. I am a 15 year old Sophomore at Alhambra High School, CA.

The bridge I've designed to enter this contest, is a redesign of my school's footbridge that connects it's track to the main campus. As apart of larger talks of school beautification, I decided to redesign the footbridge connecting the track to the main campus.

Fusion 360.

An internet connection.

A 3D Printer (or know someone that has a 3D printer).

ROBLOX Studio.

Notetaking tools (Notebooks, Pencils, etc).

A mesh.

To begin this project, you'll need to identify a location wherein a bridge could be useful.

In my case, I spent a while deciding where a bridge could be useful within the parts of the community I was familiar with, but eventually I heard of larger talks about school beautification, and figured that I could redesign the footbridge connecting the main campus to the track.

Once, you've decided on where to build a bridge, you'll need to establish what you're setting out to do.

For me, when I found my location, I ended up creating several criteria that my final design should meet.

• First, and foremost, the bridge should be safe to use.
• Second, the bridge should be relatively cheap to construct (I ended up setting a budget of $40,000).
• Third, the bridge should look appealing.

Once we've set out goals, we begin researching on how to achieve those goals.

For me, I first began research into the dimensions of the bridge, and using Google Earth I found it to be 30 meters by 4 meters, however there's a degree of error since the measurements yielded are not 100% accurate, but nonetheless it was still my best option for measuring it.

After getting the dimensions, I began researching the associated costs with demolishing this bridge. While there isn't necessarily a set price I could've used to estimate it, I did find out that commercial demolition typically have a cost range of $4-8 per square foot. I ended up deciding to split it down the middle, and use an estimate cost of $6 per square foot. After converting the area of the bridge from meters to feet, I then multiplied the area (~120 square meters or ~1,300 square feet) to get the cost which came out to approximately $7750.

Following the dimensions, I then began researching the next major factor of cost, material cost. For materials, I determined the cost of steel beams, which had a price range of $100-400 per square foot, and concrete (~$120 to ~$160 per cubic yard, dependent on source). This ended up being the deciding factor for the material, with concrete being a lot cheaper (or at least less variable) then concrete.

Furthermore, I began research into the cost of labor, which I found typically accounts for anywhere between 20% and 40%. For the sake of simplicity, I simply split it down the middle again, getting the labor cost to be 30%, and I also spent some time researching building permits, which I found should cost around $1,200.

Now after this, I began researching into potential concepts and designs. First, I began research into how digital displays, with the end goal being to integrate digital displays into the bridge. These displays would work to publicize events/fundraisers/campus news. While the concept did get fairly far, even getting partially designed in Fusion 360, it ended up being cancelled I took some time to think about it. This was due to a number of factors, namely impracticality (social media being a much better form of communication between the school and student body), costs (the calculated costs exceeded my given budget by a considerable margin), and community feedback (many people I asked ended up disliking the overall design due to how thick and large it was overall).

After returning to the drawing board, I then began research on incorporating nature (namely plants) into my bridge. I began research into Southern California's native flora, and also learned that vegetation could also help to reduce temperatures, which had the bonus of combating the overwhelming heat that can occur here. I ended up learning about several different plants that could be useful, such as Calystegia Macrostegia (A type of morning glory), which blooms into beautiful flowers, while also being a climbing plant, so it could be useful for making bridges look more appealing. It's also relatively low maintenance, being decently drought tolerant once fully established, and flourishing in full sun. Other plants such as Aristolochia California (California Pipevine), and Lonicera Hispidula (California Honeysuckle) also showed themselves to be potential candidates for incorporating into the bridge.

Using the research obtained in step 3, we begin designing the actual bridge.

First, I used a notebook to sketch out the general design of the bridge, without considering the cost, or other factors. After I came together with a basic design that I liked, I then began to optimize it, using my set goal as a benchmark for the design that'd be made in Fusion 360.

While I'll be focusing on the design that ended up getting finalized for entry, there were other designs that did end up getting to this step, but ultimately were cancelled after evaluation showed they didn't meet the set goals. For this final design, I intended to incorporate flora into the bridge, and while early designs focused on being a conducive environment only for the plants I researched into, I decided it'd be just be simply better if the bridge could support a general range of vegetation. The simplest method of doing this, was simply creating 2 shallow trenches on both sides, which gave a clear place for garden beds, without making student traffic more congested by blocking space.

As for another matter, I decide to add a fence that would more closely resemble a long arched garden trellis. This would have a twofold purpose, one being to allow climbing vines to grow on the fence, and another being to enhance student safety. There'd be several concrete arches that'd provide support to the fence, and would also provide some shade should the school decide they want to add plants that need some shade in order to properly thrive.

After getting the general design down, I decided to iron out the details, making the deck 30 meters by 5 meters by 0.5 meters. The dimensions of the trenches would end up being 30 meters by 0.7 meters by 0.2 meters respectively. As for the arches, they'd have a radius of ~7 meters, and would end up being 0.05 meters long, 0.02 meters wide. In total, there'd be 22 arches.

Now, with the details ironed out, I then translated this design from notebook, into Fusion 360. I wasn't all too familiar with Fusion 360, since I'd never used it before this point, but after learning the basics, I ended up creating a design that I felt was satisfactory.

With our design done, we need to now evaluate how well it fulfills the goals that've been set.

Using the gathered information from my research, I ended up estimating the total cost of the bridge to be approximately ~$30,200, with ~$7750 going to demolition costs, with another ~$12,500 going to material costs, ~$8,500 going into labor, and ~$1,200 going into permits. With that, I'd cleared my set budget of $40,000 by a good margin.

Moving on, there was the matter of safety, namely could the bridge actually hold itself up, alongside the loads it could expect to be holding. Assuming that the school used the trenches fully and placed as much garden beds as possible, there would be around ~12,000 pounds of dirt, with additional loads of ~13,500 pounds being derived from people crossing the bridge (at most three classes are using the track at any given time, and each class is typically around 30 people. Using the average weight for a young adult, ~150 pounds, and assuming that for some reason everyone decided to use the bridge at the same time, we got around ~13,500 pounds). Assuming that the type of concrete used is 3,000 PSI concrete, it should be able to comfortably support the weight of both the dirt and people crossing it at any given time.

While this requirement was stated in my set of original goals, I did end up deciding to include this into my evaluation, namely how long it'd take to build. While the estimate may not be all too specific, without speaking to a contractor I did estimate the bridge to take around 6-9 months to build. I simply assumed that it'd probably take longer to build than what I actually expected, since things can go awry, such as building permits (and other paperwork) taking longer to process, to supply chain issues, etc. To adjust for this I tacked on additional months to the estimate. Now, I was aiming for a bridge to be done within a single school year, since the road would probably end up being closed during construction, which would inconvenience basically everyone, since traffic becomes significantly more congested.

Lastly, there was the subjective matter of looks. I ended up deciding whether or not the bridge met the standard of being visually appealing by asking my community members. I show them the sketches, and asked them to rate it on a scale of 1-10, and also asked them to forward it to other people they know if they were willing to. I'd take the average of all the responses, and anything above 7 would be satisfactory.

If a design were to fail any of these, I'd need to either modify or start another one, repeating steps 2-4 again. There ended up being 2 designs that made it to this point, the digital display one being the first, and another one that had a roof to provide more adequate shade for flora and students, though the roofed one didn't get a Fusion 360 design.

Now with a design made in Fusion 360, it's time to begin the rendering of the finished product.

Originally, I intended to use Blender, however I decided to switch over the ROBLOX studio to render it. The reasons being that ROBLOX Studio was simply easier and faster to work with, since I planned on recreating a portion of the surrounding area. I had some experience in both, but I was definitely much faster with creating and building in ROBLOX Studio, so I opted to do that.

First off, I began by importing the model from Fusion 360 into ROBLOX Studio. Once that was done, I began to add the textures. I decided to paint the outside in the color scheme of the school.

After I had completely texturing, I then moved onto decorations. Here I added some garden beds and vegetation, however since I couldn't find any good exact models of native flora, I simply opted to simply use generic models instead. As for vines, I also couldn't find any good generic model for it, so I simply just squished the mesh of a plant to have that act as a vine.

The third step was perhaps the longest step, since I wanted to recreate the surrounding area to give a better idea of what the bridge would look like in person. First I had to begin by taking rough measurements of the surrounding area, and with Google Earth I managed to get that. Google Earth ended up proving extremely vital to recreating the surrounding area, since it allowed me to get the rough details right, such as amount of steps in the stairs, the color scheme, and etc. Once this was done, rendering would be done as a whole.

After digital renders, we begin working on physical renders.

For me, I didn't actually have a 3D printer, but I had a friend who was willing to help me out with it. The only issue being I didn't have a good idea on 3D printing and it's limitations, so when I scaled my project down into centimeters and sent it to him, it turned out that the thing was not at all printable.

The fence was too thin, and simply couldn't be printed out. After a while of thinking, I ended up modifying the design to be more 3D printer friendly, removing the fence and changing the dimensions of the arches by a little bit. This ended up being a perfect compromise, since it still resembled the actual digital model.

Now, to make the fence, I simply opted to use a mesh instead, and would layer it on top of the arches. While the mesh itself was a bit uncooperative, and also didn't respond well to being taped down, I did manage to get it to work in the end.