Bridges are an important part of the world around us, helping people and vehicles cross rivers, valleys, and roads. But did you know you can build your own strong bridges using LEGO? In this lesson, we’ll explore four types of bridges—beam, arch, truss, and suspension—and learn how to build them using LEGO bricks. Each section includes step-by-step instructions, fun challenges, and engineering tips to make your bridges as strong as possible!
The Beam Bridge: The Simplest Structure
A beam bridge is the most basic type of bridge. It consists of a flat surface, or beam, that is supported at both ends. The weight of the bridge and anything on it pushes straight down, so the support pillars at the ends must be strong enough to hold it up. To build a LEGO beam bridge, start by creating a base support with two LEGO towers at each end, ensuring they are at least five bricks tall. Then, create the beam using long LEGO plates or bricks to make a straight, flat bridge that connects the two supports. Strengthen the beam by adding additional layers of bricks on top to make the bridge more rigid. Once complete, test its strength by placing small objects like toy cars or LEGO minifigures on the bridge and seeing how much weight it can hold.
To make a stronger beam, overlap bricks like real-life engineers do to avoid weak connection points. If you’re up for a challenge, try building a beam bridge that can support a full LEGO car without bending!
The Arch Bridge: Strength in Curves
An arch bridge is characterized by its curved shape, which distributes the weight of the bridge and anything on it along the arch. This makes it one of the strongest bridge designs, a technique used in many ancient Roman bridges that still stand today. To build a LEGO arch bridge, start by constructing the arch using curved LEGO bricks or by stacking sloped pieces to form a smooth curve. Then, build strong support pillars on both sides to hold the arch in place. Once the arch is stable, add a road by placing flat LEGO plates across the top.
The key to a strong arch bridge is the keystone, which is the center piece of the arch. It plays a crucial role in keeping the bridge intact, so be sure it is placed securely. If you enjoy a challenge, try building an arch bridge without using any flat plates for support!
The Truss Bridge: The Power of Triangles
A truss bridge uses a series of triangles to distribute weight and make the bridge stronger. This type of bridge is often used for train tracks and to support heavy vehicles. To build a LEGO truss bridge, begin by constructing a long, sturdy base like a beam bridge. Next, add triangles along the sides of the bridge using LEGO bricks or Technic pieces. These triangular supports help distribute weight more effectively. To further strengthen the structure, connect the triangles with horizontal beams to prevent wobbling. Once built, test its strength by placing small objects or LEGO cars on top and observing whether it holds more weight than a regular beam bridge.
Triangles are the strongest shape in engineering because they do not bend easily, making them perfect for reinforcing bridges. For an extra challenge, try building a truss bridge that can hold at least three LEGO cars without collapsing!
The Suspension Bridge: Hanging by Cables
A suspension bridge is supported by cables that hang from tall towers. The weight of the bridge is held by the cables, which help distribute the load evenly. Some of the most famous bridges in the world, like the Golden Gate Bridge and the Brooklyn Bridge, use this design. To build a LEGO suspension bridge, begin by constructing two tall LEGO towers on either end of the bridge. Next, attach suspension cables using LEGO string pieces or Technic chains, connecting them from the tops of the towers. Then, create the roadway using a long, flat section for the bridge deck and attach it to the cables. Finally, test its strength by hanging small weights or placing LEGO minifigures on the bridge to see how well it holds up.
The cables need to be tight enough to support the weight of the bridge deck while allowing some flexibility. To take your building skills to the next level, challenge yourself to build a LEGO suspension bridge that spans at least 30 centimeters (12 inches)!
The Ultimate LEGO Bridge Challenge
Now that you’ve learned about different types of bridges, it’s time for the ultimate challenge: build the strongest LEGO bridge possible! Choose any bridge type and test how much weight it can hold before breaking. You can also experiment with combining different bridge designs to create an even stronger structure. Try extending the length of your bridge, reinforcing weak points, or adding more support pillars to see how it changes the strength of your build.
Conclusion
LEGO bridges are a great way to explore engineering and design while having fun. By using different bridge types, you can experiment with strength, balance, and creativity. Keep testing and improving your designs, and soon you’ll be building bridges as strong as real engineers! If you enjoyed this challenge, consider building a LEGO city next, complete with roads, buildings, and even moving vehicles!
