I started this project as a way to help my grandmother with a ditch that formed from a combination of hurricanes and constant rain. My parents have tried to fill it in, but everything they tried simply washed away after a few months. When I saw this competition, I found it was the perfect motivation to get me out of my bed on my time off and do something potentially worthwhile. By the end however, I can definitely say I learned a lot about how the designing process works and why it is so important to do everything in order.

Information for the Make It Bridge contest: I am 14 years old as of writing this, but by the time I submit, I will probably be 15. I am in 9th grade, going to 10th, and I live in Mississippi, U.S.

Supplies

I used Tinkercad for the designing process, and the physical materials needed to make the end result includes:

Base Bridge:

3: 110 in long 4x8

3: 97 in long 4x8

24: 72 in long 4x8

> 150: 1 in diameter bolts at least 1 foot long, or > 300 very large screws/nails

The base bridge won't hold itself, so one of the supporting designs below will be needed in addition to the base bridge.

Wire Support:

4: 200 in 8x8

350 ft: 1 in diameter cable

50: screwable hooks (> 1 in diameter hole)

Pi Support:

1: 72 in 8x8

2: 11 in 8x8 (for no hole digging design) or 36-72 in 8x8 (for hole digging design)

Step 1: Making a Bridge

The first step of my process should have been to learn more specifics about the hole so that I could better adapt my bridge, but I wanted to jump straight into designing as that was much more fun than taking a trip away from my computer. In doing so, I created this wooden bridge that uses 2x4 planks on approximately 8x2 foot planks that inclines to a center plank and is then mirrored for a decline back down to the bottom.

As the time passed midnight, I at some point read that the project was for a pedestrians, so I added steps for more convenient access forgetting that this bridge was meant for small vehicles and pedestrians. When I woke up in the morning, I realized my mistake, but I liked the design too much to scrap it. Because of this, I added poles on the sides for a rope railing, duplicated the project, and started again with a little bit more of a template.

Step 2: Updating the Bridge

After my first mistake, I decided to make a jeep bridge with no slope to make it a seamless transition between the ground and the bridge. I still had not measured the hole. I started on a duplicate of the first bridge, and moved it to the side first as I added terrain that I thought could be the hole. I then un-grouped everything until the planks were separate from one another, and dragged the large plank to span the gap. I then realized that if I did build this bridge, digging holes for the main planks wouldn't be that hard, but for the top planks, it would be much more difficult. I therefore raised my idea of the bridge to have a slight bump to accommodate my laziness. I added the top planks, and looked at it for a bit wondering if it would hold a jeep. Realizing it probably wouldn't, I added some support on the bottom bearing a triangular resemblance because triangles are the strongest shape and as you can see by my terrain, there is potential for the hole to become a river with a strong current during the storm which would leave the downward facing planks less stable than side ward.

Finally, I added some reflectors to the sides of the bridge to make it more visible in the dark. While I first thought of adding lights, I realized they would have to have their batteries maintained which is more of a hassle than anyone wants to deal with. There are almost always clouds in this area leaving solar panels out of the options, the water below the bridge is inconsistently flowing, and the jeep has low powered headlights, so I thought it would be reasonable to simply use reflectors.

Step 3: Gathering More Information

There is not much to say about this design as it was a sort of middle child. I had gotten a side picture of the hole and built the terrain to slightly resemble the hole, but there are trees and shrubs on each side of the hole making the path turn around 30 degrees to the left or right that I had not taken into account. I don't remember much about why I was not thinking about the curve, but it was probably due to a lack of sleep, as a lot of mistakes I make are. I was not at the site personally due to my parents' trip being in line with my school, so I could not take pictures or measurements, but these are what they gave me. In the end, I did not like this design enough to add finishing touches to make it look better like a water level and possible rails.

As a side note, I do not know if it is my inexperience or the picture, probably both, but this hole does not look nearly 16 feet long to me. I could easily and have been wrong before though. I do know from being there in person in the past, that it is a pain to get over the steep ledge with the jeep, so I can believe the depth, if it isn't deeper. As you can see in the last picture, my parents told me to make the bridge around 6 feet wide, but if I would ever have to drive over that bridge while turning, I know I am going to need 7-8 feet.

Step 4: Creating a Terrain and Bridge Skeleton

Next, I converted everything from inches to millimeters on a 1-1 ratio so that my design could somewhat fit in the Tinkercad workspace without dealing in decimals. I created the terrain with this new ratio, and while it may not look the best with hard angles in it, it is better than what it was before. Besides the looks, it gives me two points to connect my bridge to with a no go zone at the sides and bottom. Now that I also have a ratio to go off of, I resize my planks to fit lumbar standards to avoid wasting excess wood, and I built another relatively flat bridge that uses a similar design as the last step of my build, marking the sizes of all the lumbar and bolts I am using for easier access when I come back to make a list of materials.

Now that there is a floor to the bridge, it is time to add more support. There are 6 (later changed to 3) large planks under this bridge paired up, and I have to connect them in the center somehow so they don't cave in. I have a few ways to do this, so to find the best of them, I could make a chart listing the pros and cons of each or I could make a design for each of them and see which one turns out the best. Because I have more time than I know what to do with, I will go with the latter option, though I recommend the prior option to all others who don't want their work to go to waste.

Step 5: Identifying Support Options

The first image with the pi looking support would indirectly connect the two bridge halves leaving them with an easy way to move if a hurricane were to come. This idea would be great also if there were a need for a bridge somewhere else with no time to spare. All you would have to do is move the centerpiece and halves separately. There is the problem of the centerpiece being embedded into the ground however. Not only does it take time to make the holes, but during a hurricane, it would be worn down as most of the time, it would not be worth the effort of removing it from its place. This is especially harmful because this hole was made from hurricane water running downstream. This could work out, but I think it would be best if nothing were to go under the bridge to keep away from corrosion.

The second image with the medal connectors may stop the bridge from collapsing under its own weight, but there is no way it would hold up a jeep. With more support from above however, this could be a good option as it does not touch the ground leaving it less susceptible to corrosion.

The third image with the triangular design is something that I thought of, but it didn't work out as well as I thought. I made this design at first with the idea that the all wooden aspect of the design would hold up the bridge (image 4), and I still think it would, but there is also the choice of cable. I know that if this assortment of triangles was upside down, and there were a wire that was anchored to the ground holding all of them together, this would be a form of suspension support, but there is no room below the bridge, so I can't do that.

The fifth image shows a full wire suspension bridge that would use the top of the 4 stakes as ground points that would lift the bridge up to their level. More wire may be needed to support all of the posts as well. I do not know the exact price, but I imagine this amount of metal would be considerably more expensive than most of the other ideas above, but this design plants the bridge in place making it very difficult to move in the future. This could be fine however because it could be the sturdiest of all the designs below as long as the 4 poles stay standing. If this idea were to be used, it would probably be a good idea to plant the bridge itself into the ground as well to keep it from swinging around in high winds. This idea would take the most maintenance, as the cable/wire would loosen from the hooks holding the bridge up as well as potentially fray or unravel over time. This design could also feel claustrophobic when riding in between it as it shortens the drivable part of the bridge by 1-2 feet depending on the wind. This generally would not be a problem as you can just widen the bridge, but if the bridge makes it to the bushes and trees on the side of the road, the price of removing the trees must be taken into account, and I imagine that would not be cheep.

Step 6: Singling Out the Best Designs and Adding Final Touches

For the cable/wire suspension bridge, I lowered the bridge itself so it anchored a bit more into the ground, and it provides minimal bumpage when entering and exiting the bridge on jeep.

I voted out the metal connector design because it simply would not support a jeep.

The wooden triangle truss could work if I added wooden planks between the triangle's tops and anchor it to the ground, but I am worried the wood would deteriorate too fast under constant pressure and water. There are also trees above this bridge so the water would bring unwanted small material which would only speed up the deterioration.

I also liked the pi support design as it gives an option for either a permanent type of bridge with the support being dug deep in the ground, or an extremely temporary bridge with no holes being dug at all but rather just a large base for support and easy extraction.

With all of this in mind, it would probably be best to consult the sponsors due to the vast differences in cost, upkeep, and looks. Because of this, I put the materials for both designs separately in the supplies step.

Step 7: End Results

As I was taking these pictures, I realized that you could not open multiple comments at once and they don't show in the previews, so the fourth picture here is an example of what they look like. All of them look the same with just different numbers on them.