The Arched Pedestrian Bridge

Hi! My name is Angela Wang, I am a incoming Junior to Staten Island Technical High School, New York, I'm currently 15 years old. The Images shown is my take on a redesigned/replacement of the Lumberville–Raven Rock Bridge, over the Delaware River in the US.

Supplies

Resources used for creating the bridge model:

1. AutoCAD software
2. Google maps
3. Paper and Pencil (my draft of bridge ideas)
4. The internet (for inspirations and ideas)

Step 1: Brainstorming Ideas + Finding a Suitable Location

From the get go, I knew that I wanted to make a bridge that blends into, and giving access to the nature around it. I brainstormed many different ideas for the location of my bridge, and during my research, I found many polluted rivers around the world. One of which was the Delaware River, which is the most polluted river in the United States. This is where I originally decided that I wanted to create a bridge that helps with the plastic pollution aspect of the water in the Delaware river. I researched how people were combatting the pollution crisis, and came across a website that showed many different mechanical contraptions made for that purpose. The most famous of which are the "interceptor", the “Seabin Project”, “Boom it”, and more. I will be leaving the link to this website below.

After reflecting on the amount of time I had for creating the model of my bridge, I decided that I didn't have enough time or experience to create the anti-pollution mechanical bridge I had in mind. Since I don't have the time to create the bridge that I originally had in mind, I instead decided that I wanted to create a bridge on the Delaware river that helps bridge the gap between the people living in the area and the nature around them. Now it was just the problem of finding a location for my pedestrian bridge. After a bit of research, I found the Lumberville–Raven Rock Bridge, a pedestrian bridge designed as a footbridge and suspension bridge on the Delaware River in the United States. The bridge helps to connect the people in Pennsylvania to many forests and parks in New Jersey, such as the Bulls island recreation, and the Delaware Canal Sate Park. The Lumberville–Raven Rock Bridge is the perfect location for my bridge. With this location in mind, I officially decided that I will be creating a bridge to redesign/replace the Lumberville–Raven Rock Bridge.

Step 2: Brainstorming Designs

After deciding on the location of my bridge and the purpose of my bridge, I started to look for bridge inspirations on the internet. With a quick scroll on the internet, I quickly found that I loved the beautiful and majestic look of arched bridges, or more specifically, arched suspension bridges.

I then looked into the physics of the bridges, and found that there are two forces at play: compression, and tension. As I sketched my design out, I tried to apply the two forces to my bridge design in order to gain a better understanding of my bridge. The design ended up going with was a cross arched suspension bridge design, with two pairs of cross intersecting arches, connected to the bridge via crossed cables. After analyzing my bridge design, I noticed a key flaw. How was my bridge suppose to have cables cross over each other without intersecting? After a bit of thought, I quickly found a solution. Instead of having the cables connect to the same part of the bridge, I designed the cables from the different sides of the arches to connect to 2 different parts of the bridge. I also added railings and a few new stabilizing components to my bridge design sketch, in hopes that it would help stabilize the arches.

Step 3: Dimension Challenges

Throughout the project, The toughest part of this project would definitely be the actual designing and modeling process for me, as I had a pretty hard time trying to modeling my bridge on AutoCAD. This is mainly because at one point, I lacked the planning of the dimensions of my bridge. At first I just went with the flow, modeling what seemed right as I learned how to use AutoCAD. But after some thought, I realized my mistake, without a solid plan for my model, the sizes of the different components of my bridge would be out of place.

With this new found realization, I started to research the dimensions of the Lumberville–Raven Rock Bridge, and the approximate depth of the Delaware River my bridge will be modeled on. This way, my 3D bridge model will be more accurate and realistic to what the bridge should look like when actually built. I found that the Lumberville–Raven Rock Bridge was approximately 688 feet, and that the average water depth of the Delaware river in Philadelphia was around 40 feet. With this information, I sketched my final draft of my bridge before modeling my bridge.

Step 4: Modeling

After getting everything ready, I finally start the modeling process on AutoCAD. I never actually used the 3D version of AutoCAD before, I had only learned the very basics of AutoCAD 2D, so I had a difficult time starting out. But I found many resources online that helped me learn the basic commands and techniques to modeling a bridge.

I learned how to us many useful commands such as:

1. Extrude, gives 2D lines thickness, turning it into a 3D object. Used to create the basic rectangle shapes.
2. Loft, creating 3D solid surfaces between several cross sections. Used to create the arches.
3. Sweep, creating 3D solid surfaces by sweeping a 2D line along a path. Used to create railings and cables.

Using all the commands and techniques that I learned, I created:

1. Decking + Railings: Includes a 12 feet walkway for pedestrians, as well as a 6 feet bike lane on either side
2. Arches + Arch stabilizers/connecters
3. Cables: Connecting the arches to the deck of the bridge
4. Foundations: The base of the bridge, and connecting and stabilizing the arches

Step 5: Final Product

Shown above is the final product of my pedestrian bridge model. Although there was some trial and error, re-modeling, and many challenges in making this bridge model, I am very satisfied with the results of the bridge. Building this bridge model has been such an eye opening experience to the world of 3D modeling and engineering, and I had a blast making this 3D model of my Arched pedestrian bridge.