Bridge is a structure that carries pathways, railroads, or other such things across an obstacle. But bridges themselves are much more intricate. Their beauty lies in the abilities granted to them by their design. Indeed, architects and engineers have now been able to design bridges without support in between, something people commonly referred to as a hanging bridge.
While it will be difficult to engineer a complex design if you are in school, there are still various interesting ways for you to explore the world of bridges via DIY bridge projects. In this article, we will discuss a small bridge-building project you can undertake using materials easily available at home.
A bridge is a structure that allows 
you to pass over an obstacle without significantly affecting the path that lies beneath it. The second point here is important. Even though you can have bridges that take no consideration for what lies beneath them, a bridge’s true beauty is the fact that it allows passage both over and under.
In the image of Victoria Bridge from Brisbane, Australia attached above, you can see how there is enough path for water-bound transportation to pass underneath the bridge. Another fine example is the Tower Bridge of London, which opens up to provide a path for the ships to pass underneath it.
There is a plethora of factors on which we can classify bridges. Based on construction, there are five main types of bridges. Let us take a quick look at these types.
A beam bridge is perhaps the simplest type of bridge possible. It is a simple beam placed over two supports on either end. You can make a DIY model of this bridge by placing an ice cream stick on two bottle caps. Take a look below −
An arch bridge looks exactly like it sounds. It is shaped like an arch and usually does not have support underneath it in the middle. A rough diagram can look something like this −
Since the entire weight of the bridge rests on the supports on either end, the supports have to be well-made and solid.
A tied-arch bridge is quite similar to an arch bridge. However, it has support in the middle by using vertical ties.
Interestingly, the arch-like structure is kept in place via strengthened chords, which connect either end of the arches.
Suspension bridges have the most elegant-looking design of all. They seem like an architectural marvel, especially when their size increases to majestic proportions. The golden gate bridge is an example of a suspension bridge.
The weight of suspension bridges lies on their decks. The deck itself is supported by vertical suspenders supporting the suspension cables. Note that depending on the size of the bridge, one would need towers to hold up the suspension cables.
If you haven’t reached higher secondary school, you might not know this yet. But when it comes to bearing weight, a triangle is an amazing shape. This is because a rectangular or circular shape can bend under pressure and deform. However, a triangle dissipates the weight on it in two directions, allowing it to withstand higher levels of stress.
This ability of triangles is used in the design of truss bridges. While it is difficult to describe them in pure words alone, the following diagram will help make the concept of truss bridges clear.
The name truss is given to a framework consisting of beams, rafts, etc. that can support a bridge or a roof. In the above image, the triangles are constructed of trusses, which hold the upper and lower part of the bridge together.
Let us now discuss a simple DIY project you can undertake to build a bridge on your own. Here’s what you will need.
Ice cream sticks.
Spaghetti or noodles.
Some hot glue and a hot glue gun.
Some soda cans are similar in height and weight.
A few items of known weight.
Before we start, remember to perform these projects under adult supervision since hot glue can cause burns. Here is the procedure −
Draw a rough design in your notebook. You can start with a simple beam bridge and go all the way up to suspension or cable bridges.
Create a place for your bridge by placing two soda cans a few cm apart. You will use your bridge to cross from one soda can to the other.
Use a single ice cream stick to create a beam bridge.
Use the noodles/spaghetti sticks to create ties for your suspension bridge.
Try and figure out what other bridges you can make with items you can find at home.
Once you have created your bridges, it is time to test them. Use the known weights to see which bridge can withstand how much weight.
Record your observations in a notebook.
Bridges are one of the most remarkable architectural and engineering achievements that allow us to tread across obstacles. The best part about bridge construction is that if there is a path that lies underneath the bridge, it is not obstructed by the presence of the bridge. The Tower Bridge of London is a famous example of this capability. Bridges are classified into various types depending on several factors. But based on their design, we can classify them into a few major types like arch bridges, beam bridges, suspension bridges, etc. Of these, a beam bridge is the simplest.
One can easily make DIY models of bridges at home with simple items like ice cream sticks, noodles or spaghetti sticks, hot glue, matchstick, soda cans, and other similar items.
Q1. State a few types of bridges apart from the ones mentioned above.
Ans. Cantilever and cable-stayed bridges are two famous types of bridges that have been around for a long while. The design of the cantilever bridge was a major engineering achievement when initially proposed.
Q2. State the most unique property that is common to all types of bridges.
Ans. The robustness and the longevity of bridge designs are the most remarkable property. The bridge designs we know today were proposed much longer than one can imagine. And yet, engineers haven’t made any major changes to those designs for the very simple reason that these designs work.
Q3. Which type of bridge is the most expensive to build?
Ans. Due to the span they have, the tower size, and various other factors, suspension bridges have the highest cost. Today, they can easily cost over a billion dollars to build. Interestingly enough, the first generation of suspension bridges was constructed out of twisted grass. You can appreciate the age of this design from that fact.
Q4. What is the strongest type of bridge?
Ans. The truss bridge is the strongest compared to its weight, even though it has been around for centuries.
Q5. What type of bridge construction is most commonly utilized?
Ans. Unless there are specific requirements, the beam bridge is the most common and the simplest bridge available for our use.
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