What's inside Tower Bridge? (London, England)

Inside of this bridge in London, there's a lot of machinery that allows the bridge to open and close. In this video, we'll see how the bridge was built, where you can go on public tours, and the inner workings of the bridge. Today, we're going to London, England. This is the River Thames, which goes through London. There are many bridges crossing the river. This one right here is Tower Bridge. Let's clear up some confusion. This is not London Bridge. This is Tower Bridge. If you want to see London Bridge, then you've got to come all the way down here to see it. This is London Bridge. Quite a rich history that goes back almost 1,000 years. The bridge has been rebuilt several times. Today, it's just a typical bridge made out of concrete and steel. To make this even more confusing, over here we have the Tower of London, which is a historic old castle and royal residence. So we have London Bridge, Tower Bridge, and Tower of London. We'll try hard not to get these mixed up. For this video, let's focus on Tower Bridge. Tower Bridge is known for its ability to raise up the sides to allow tall ships to pass by. And you may have noticed, once they pass Tower Bridge, these tall ships can't go much farther up the river. So what is the point of building a fancy bridge to allow tall ships to pass through? Well, today, there aren't too many large ships that need to access this area, but it wasn't always this way. This part of the river around Tower Bridge is called the Pool of London. Back in the 1800s, it was packed with ships of all sizes. It was one of the busiest shipping ports in the world. If you wanted to cross the River Thames, you had to go all the way to London Bridge. They needed to build another bridge to connect the two sides of the river, but the challenging part is to allow ships to still be able to access the upper pool of London. The City of London held a design competition for the bridge. I find this interesting because other famous structures also have had design competitions. We talked about them in my previous videos, Sydney Opera House and the Gateway Arch. For Tower Bridge, they had about 50 entries with some very interesting bridge designs. One of them was for a sliding bridge. This had six piers inside the river with motorized rollers to move the bridge platform. Ships would always be able to pass in between the piers. A swing bridge with rotating sections. And this was called the duplex bridge, having two portions of the bridge swing open and closed as needed. A high level bridge would involve hydraulics, which would lift passengers up to the higher section of the bridge. A transporter bridge to allow safe passage to the other side. And one of the most promising ideas was a drawbridge, allowing the two sides to be lifted when needed. The right idea, but the sides of the bridge would be too heavy to lift. They took this idea and modified it. Instead of a drawbridge pulled from above, they turned it into a bascule bridge with counterweights on each side and hydraulic motors to open the bridge. Instead of an arch, they made a high level pedestrian walkway above. This way foot traffic could pass to the other side, even when the bridge was open. Bridge construction started in 1886 and took eight years to build. First, the foundation had to be built into the riverbed. One of the rules was that the construction could not block the river traffic. Ships must still be able to pass during this time. Over 2000 workers were involved in the construction. The steel frame was built first, then the external stone and masonry would go on last. They built the bridge to blend in with the older style buildings around it, like the Tower of London, which we talked about earlier in the video. Tower Bridge officially opened June 30th, 1894. Tower Bridge quickly began to support heavy traffic. The high level walkways were a great idea, but people soon discovered that it took a long time to climb the tower, cross the walkway and come down the other side. It was usually quicker just to wait until the bridge was lowered again. The walkway also became a dangerous place because of criminals and pickpockets. It was closed in 1910, but later reopened for public tours. The bridge survived two world wars and it did receive some minor damage. In 1943, it was proposed that they would build a glass covering for the bridge to protect it during World War II. Probably not the best idea and they never actually built it. The bridge was originally chocolate brown. It was darkened by soot over time. In 1977, the bridge was painted with red, white and blue to celebrate Queen Elizabeth. These are the colors that remain today. In 1982, the Tower Bridge exhibition opened to the public. You could now tour the towers and walk across the high-level walkways. We'll take a closer look at the tour later in the video. In 2012, the Olympics was in London, so the Tower Bridge briefly featured the Olympic rings hanging from the walkways. Today, the bridge is still critical to London traffic. It carries over 20,000 vehicles per day. Let's look at some parts of the bridge. There are two piers. That's the part of the bridge that rests on the riverbed. There are two towers, a North Tower and a South Tower. And on the sides, we have the abutments. These are the smaller towers. Tower Bridge is considered to be several different types of bridges. First and foremost, it's considered a bascule bridge. Bascule is a French word for seesaw. There's a counterweight on each of the sides, though the motor can rotate them open so the bridge can go up. It's also considered a suspension bridge with support cables to hold the sides of the bridge up. When it was first built, it was also a cantilever bridge with all of the weight only supported at each end. In the 1960s, they added a support cable which turned this walkway into a suspension bridge. The high-level walkways provide tension in between the towers. Suspension cables will pull the towers, but the walkway provides the support to keep everything balanced. Tower Bridge rests on two concrete piers. Inside, you'll see the bascule chambers, which is partially below the waterline. This is the room which allows the extra space for the bascules to open. Maintenance workers need to come down here, and occasionally, they will do guided tours for the public. Here's the engine room, which is powered by a more modern electrohydraulic system. There are four engine rooms, two for each side of the bridge. You can imagine how important it is that the bridge always opens and closes when they need it to. They used to have older hydraulic engines in here. It ran off of water pressure that came from steam-powered engines on the south side of the bridge underneath the roadway. This machinery is not in use anymore, but today, you can go see it on a public paid tour. Let's step through how this machinery works. First thing you'll see when walking through the door is the boilers. They take the coal to heat the water to produce the steam. This makes me think of the Titanic, which was also powered by steam. Boilers produced the steam, which then turned the massive reciprocating engines. There is a very similar process here for these smaller engines. The steam pressure drives these pistons back and forth, which then turns the flywheel. This motion is used to build up water pressure, which then goes to the accumulators. You can see two of them here. These are like the batteries. The water pressure builds and the accumulators rise into the air. In fact, that's the purpose of the building on the side of the road, to give space for the accumulators to rise. When it's time to use the hydraulic pressure to lift the bridge, the weight of the accumulators pushes the water down. The water went all the way to the engine rooms in the two piers. There are four engine rooms, two in each pier, and two more additional accumulators in each pier for a total of six accumulators. This ensures that they would always be able to store enough power to open the bridge. There were two engines inside of each engine room. This way, if one of them needed repairs, the other could still operate the bridge. Remember that the bridge is no longer powered by these older style hydraulic engines. Today, this has been replaced with a more modern electrohydraulic system. Notice that they left one of the older engines in there. It's nice to be able to see how technology evolves over time. Initially, it was open more than 20 times per day, but now there is much less boat traffic and it's only opened on average about three times per day. You can check the schedule of when the bridge will lift, but sometimes this is unpredictable. It takes just over a minute for the bascules to open. Usually they don't need to open the bascules all the way, but when a Royal ship comes through, then they open them all the way as a sign of respect. There are four cabins. The two on the west side are the watchman cabins used to observe approaching ships. This was how it was originally set up. However, in the 1990s, this cabin was converted into a ticket office to buy tickets to tour the inside of Tower Bridge. The two cabins on the east side are control cabins used to control the raising and lowering of the bridge. Today, the southeast control cabin still has all the old equipment inside to showcase what it was originally like. And the northeast control cabin has the modern equipment to control the bridge. So today, when the bridge is raising or lowering, there's a person inside of here who is controlling it all. When the bridge was designed, they set laws in place to make sure that the river traffic was the priority. Today, there is much less river traffic, but it still does happen. There's no fee to raise the bridge. You've just got to notify them 24 hours in advance. Before raising the bridge, the staff will be in contact with city authorities to make sure that no emergency vehicles, such as an ambulance, needs to get through. When it's time, they first make an announcement telling everyone that the bridge is about to lift. The traffic lights go red and the gates are closed. They usually have to wait the longest for pedestrians to finish crossing. In the middle of the bridge are the nose bolts. Once the traffic is cleared, these will be retracted to the south bascule. Now, they can slowly raise the bascules. Once the ship is through, the bridge is slowly lowered, the gates are opened, and traffic is allowed through once again. In December 1952, they had a close call with a red double-decker bus coming from the south. The watchman was supposed to ring a bell and close the gates. On this day, that did not happen. The bus driver was driving onto the bridge and suddenly realized that the bascule was starting to rise. The way it worked back then, the south bascule started to rise first. With some quick thinking, the bus driver decided to accelerate and jump the gap. It was about a six-foot drop. Remarkably, the bus landed on the other side. Among the 20 passengers on board, there were some injuries, but everyone survived. Today, the system is a lot more automated, ensuring that the bridge is completely clear of any traffic before the bascules start to rise. If you come to this area of London, make sure to check out other interesting sites nearby. Tower of London, we saw this earlier in the video. HMS Belfast, a World War II light cruiser that is now a museum. The Shard, which is the tallest building in the United Kingdom. And if we zoom out a little more, you can see Elizabeth Tower or Big Ben, which is over here. There's a lot of interesting mechanisms inside of there. You can learn more about this in my video, all about Big Ben. For Tower Bridge, there is actually quite a bit you can see. It's completely free just to walk across the bridge and take in the views. If you want to go inside the towers and the walkways, you need to purchase a ticket. You can do that online or go to the ticket office on the Northwest side of the building. It currently costs about 13 pounds for an adult ticket. Your tour will start on the North Tower. There is a lift for those that need it, but otherwise you'll come over here to take the stairs. As you climb the stairs, you'll be able to see displays about the tower and London history. At the top, you'll find more interesting displays and then head through the doors to gain access to the walkways in between the towers. During busy times of the day, this area will be packed with tourists. In the center, there is a glass floor. This was built in 2014. You can look down onto the traffic down below. For those brave enough, you can actually walk out and stand on the glass. I hope you're not afraid of heights. There are plenty of displays along the walkway and you can learn more about how the tower was built. When you're finished, you can take the stairs down the South Tower and exit on the sidewalks down below. After exiting Tower Bridge, the tour isn't over. The last part is to see the old engine rooms, which was used up until the 1970s. We saw how these worked earlier in the video. There's a blue line to follow to get to the engine room. Follow the stairs down below, underneath the bridge and around the corner. The gift shop is right here, but you'll need to show your ticket to tour the engine rooms. You get to walk past the boilers and then around both of the engines to see them up close. Remember that today, these engines are not in use anymore, but they are still in motion for the public to see. Today, they use compressed air, which isn't strong enough to continuously rotate them. When these engines were in use more than 50 years ago, the steam power would have them rotating in a continuous motion. The tour then goes behind to see more displays and get a close up look at the accumulators. When you exit the tour, you'll come out into the gift shop. Make sure to take something home with you to remember your trip to Tower Bridge. If you're one of the lucky few, you can also get a behind the scenes tour that goes into the control cabin and down below into the engine room and bascule chambers beneath the bridge. But I've been told these tickets are a little hard to find. If you'd like to see behind the scenes for this video or other Jared Owen videos, then please visit patreon.com slash jaredowenanimations. You can access rewards such as high quality artwork, see how the videos are made, and even be involved in the creation process. Your support helps to grow my team so we can create these videos faster. My name's Jared. Thanks for watching.