What's inside of the Gateway Arch? (St. Louis, Missouri)

The Gateway Arch in St. Louis, Missouri has a tram system inside of it to take passengers all the way to the observation deck at the top. Let's explore how the arch was constructed, the museum underneath, and of course the tram ride to the top of the arch. My name is Jared. I create 3D animations to show and explain how things work. Hit the subscribe button to be notified about future videos just like this one. The Gateway Arch is the world's tallest arch at 192 meters high. It's similar to other structures like the Eiffel Tower, Space Needle, and Elizabeth Tower or Big Ben. These structures are icons for the cities where they are built. Let's take a look at the story for the Gateway Arch. Missouri is a state located in the midwestern region of the United States. The city of St. Louis is right on the edge of that. The arch is here, right along the Mississippi River. Downtown St. Louis is to the west of the arch. And across the Mississippi River is the state of Illinois. The arch has a unique shape. If I take a chain and let it hang down, this is called a catenary curve. Now take that same shape and flip it upside down. Now it's an inverted catenary curve. This is the shape of the Gateway Arch. It's the shape that will best support its own weight. The arch was built between 1963 and 1965 and it cost 13 million US dollars. That's almost 100 million US dollars in the year 2024. The arch has the same height and width, 192 meters. Over 1 million people come to see the arch each year. The arch is resistant to earthquakes, lightning strikes, and in high winds it can sway up to 46 centimeters. So why was the Gateway Arch built? What's the purpose of it? Let's rewind the clock a few hundred years. European colonists started arriving on the east coast of what is now the United States. Then slowly they started moving farther inland. This is termed the Westward Expansion. The city of St. Louis was founded in 1764. Shortly after, the United States became a country. This is what it looked like before 1803. St. Louis was one of the famous last stops to gather supplies before making their way over the plains. In other words, it was the gateway to the west. You see where I'm going here? In the 1940s, they held a design competition. The idea was to build a monument to honor the legacy of westward expansion. Out of 172 entries, they chose the design of Eero Saarinen, a Finnish-American architect. He had the most unique design out of all of them. He decided to build an arch that would represent the gateway to the west. That is why it has the name Gateway Arch. Sadly, Eero Saarinen passed away before construction even started on the arch. But today, he is still honored as the designer of the arch. There was a lot of criticism for the arch at first. Can we really build something like this? How would it look against the St. Louis skyline? It's almost similar to the origin story of the Eiffel Tower. Not everybody wanted it at first. Nonetheless, plans moved forward for the arch. So how do you build an arch like this? Most buildings are built with a supporting structure on the inside first, and then the outside layers go on last. This time, what we have is different than a typical building. The Gateway Arch has what's called an orthotropic design. What this means is that there is no internal structure. The metal on the outside, that is the structure. That's what's holding it up and supporting all the weight. Building a support structure just for the construction would have been enormous and not very practical. So instead, they would just start from both sides, build upwards, and then meet in the middle. Easier said than done. In 1961, they started digging the foundation for the arch, 18 meters deep, which is about six stories down. They laid concrete and steel tensioning rods in several layers. This provides a solid base for the layers of the arch. Construction of the arch actually started in 1963. The pieces were built in equilateral triangles, and that word equilateral, it just means that all three sides have the same length. Each triangular section had stainless steel panels on the exterior and carbon steel panels on the interior. The metal work was done in steel mills in Pittsburgh, Pennsylvania, and then shipped all the way to St. Louis, Missouri. The triangular pieces were too big to ship all at once, so they were assembled in separate pieces and shipped by rail. There was a railway that went right by the construction site. The triangular pieces were welded together on site, right next to where they were building the arch. There are 142 of these triangular pieces. Where they are joined together, this is called a station, and they numbered all of these. At the very top is station zero, then going down each side, station one, two, three, four, and all the way down to station 71 at the base of each leg. The triangular pieces are largest at the bottom and smallest at the very top. Once a piece was ready, it was lifted by crane and gently placed in position. As each new piece was placed, it was welded together. The welds needed to be so good that it acted as one continuous piece of metal to support the weight of the arch. Then the reinforced concrete was poured in between to make the arch legs stronger. There were two teams working together to build the sides of the arch at the same time. They had post-tensioning rods going down the sides of each leg. These helped to hold the legs upright as they were built higher and curved inwards towards each other. These cranes could only help build the arch for the first six pieces, 22 meters tall. After that, the engineers planned to use a very unique solution. The tracks were built on each side of the arch and this is called a creeper derrick. It's basically a mobile crane that will travel up the side of the arch as it's built. So it lifts new pieces of the arch in place. Once there are four pieces above the derrick, we can bolt in another piece of track. Now it's able to move up to a new height and continue working. This was really the first time that something like this had been done. These platforms can be tilted in place. That way they can stay level as they move up the sides of the arch. These letters on the side, PDM, that stands for Pittsburgh Des Moines Steel Company, one of the contracted companies that helped build the arch. The concrete being poured helped to stabilize the foundation but it was only needed to about halfway up the arch. They soon reached a point where building any higher would cause the arch to collapse inward. This means it was time for the stabilizing truss. The two creeper derricks worked together to lift it up. Once in place, this supported each side so they could continue building the arch. Another 21 pieces on each side. The construction work needed to be so precise that the legs met perfectly at the top. If they were off by just a little bit, that would have been a disaster for the project. Thanks to the engineers, this did not happen. After two and a half years of construction, there was one more piece left called the keystone. There were thousands of people that showed up to watch this crowning event and the gap for the keystone was too small, less than a meter. They knew this would happen but it was still a challenge to deal with. The gap needed to be almost two and a half meters for the keystone to fit. Part of the problem was the heat from the sun causing the stainless steel to expand. The south leg of the arch received the most sun so they decided to spray water over the side to cool it down. As part of the original plan, hydraulic jacks were put in place to move the legs with just enough room to fit the keystone. After a few tense moments, the keystone successfully went in and the workers were able to weld it in place. The engineers had done their job and the arch was now complete. The stabilizing truss could be removed and the arch could now support its own weight. It took the better part of a year to slowly bring the creeper derricks down, cleaning and polishing the stainless steel on the arch as they went. The arch was finished but there was more work to do. When Eero Saarinen designed the arch, he wanted visitors to be able to get to the top but he didn't exactly know how that was going to happen. Whatever system they used needed to be able to bring many passengers up and it couldn't distort the outside of the arch. We want the arch's shape to be unaffected and have that smooth look all the way up the side. To make things harder, the legs get thinner as you get closer to the top. The tram had to be designed with this in mind. Many industry experts of the time were stumped by this problem. How about we build an elevator? The problem is that an elevator goes straight up and down and we need something that curves. Okay, how about an escalator? These don't go straight up and down. You might make that work at first but you'd need to build several of them and that gets expensive. The main inspiration for the design actually came from the ferris wheel. This can move people around quite well and they're always right side up no matter where they are around the ferris wheel. This same idea can also be used to transport people up the sides of the arch. Dick Bowser is the engineer that came up with this solution. Instead of individual seats, the design called for enclosed cars for safety and then put all the cars together and use cables to lift them. This tram system needed to be small enough to fit on one side of the arch leg. This leaves enough room for emergency stairs on the other side. When the tram is at the bottom, the cars are below the tracks. Let's see what happens at the other end and when it gets to the top, the cars are above the tracks. Notice as it travels, the cars always stay right side up. The exact same idea that the ferris wheel has. Each tram car has just enough room for five people. About the same size as the Soyuz spacecraft crew capsule. Not a lot of room inside. Passengers can travel up the sides of the arch. There are eight cars on each side. This allows for more than 1 million people each year to ride the tram to the top. I'll show you more about the tram system, but let's back up a bit. Today, the arch is a popular tourist destination. Let me show you a few things around the area. This whole grassy area was called the Jefferson National Expansion Memorial. In 2018, it was renamed to the Gateway Arch National Park. There are more than eight kilometers of trails to explore along the Mississippi River. This is called the Grand Staircase and there is also a train track that runs underground right next to the arch. For parking, it's recommended that you park at the Stadium East parking garage. They even give a discount if you are visiting the arch. Then, you can walk to Luther Eli Smith Square. Now, this whole area was recently renovated. If you visited the arch prior to 2018, this will look a little different. The entrance is here, which leads right underneath this grassy area. This is the lobby. The information desk is here and there is a life-sized model of one of the tram cars. This way, you can see what it will be like to ride to the top of the arch. Some people find it a bit claustrophobic. The ticket counter is here and there's more to do than just the tram. You can buy tickets to the documentary movie, virtual reality theater, and even a one-hour riverboat cruise along the Mississippi River. The museum inside is free and you don't need a ticket for this, but either way, everyone going inside must go through the security line. There's a giant map of the United States on the floor and you can see some of the paths that early explorers took to travel to the west. Walk a little farther to get to the museum. There are six areas to visit inside the museum, each focused on different aspects of the history of the arch. For example, this area focuses on the history of St. Louis and this area focuses on the Mississippi River front and how that's changed over the years. This area focuses on the building of the arch, a design competition, and even a miniature model of the tram. If you bought a ticket to the documentary movie, then you'll go inside the Tucker Theater to see how the arch was built. The arch store is here. Arch Cafe is here if you're hungry. And in the center is a life-size model of the keystone piece of the arch. Remember that the keystone was the last piece they installed during the construction of the arch. There are even displays inside that will show you the view of what it looks like from the top. Once you have your ticket, you'll need to make your way to the You'll walk through a hallway and then down some stairs to get to the loading area. Your ticket will show you which door you need to wait in front of. Since the 1960s, they've had quite a few upgrades to modernize the arch. It takes four minutes to get to the top and only three minutes to get back down. With both trams operating, it can transport 80 people at a time. The doors open and you can make your way up the final stairs to the observation deck. There's room for about 100 people up here. It's 192 meters high, which is about the height of a 63-story building. On the very top of the arch is an aircraft warning light. The keystone of the arch is right here. There is also a metal time capsule that was welded inside of the keystone, not meant to be opened as long as the arch is standing. There are 16 windows on each side of the arch. If you look out the window towards the west, you get a good view of downtown St. Louis. The reason these windows are so small is because larger windows would have weakened the structure. There's limited time at the top, so take a good look. You'll be asked to come back down on the same tram car that you came up in. Note that the stairways are always lit just in case, but these stairs are for maintenance and emergency use only. At the bottom, you'll go up these stairs and then back into the common areas. When you're ready to exit the arch, you've got a few options. You can go back through the museum and out the same way you came in, or you can exit right here, up the ramps on either side, then out the doors, and you'll come right out at the base of one of the arch legs. My name's Jared. 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