 Hey everyone and welcome back to the channel. Rail systems are incredibly powerful for moving people, goods, and sometimes sushi. But train's greatest strength is also their greatest weakness. Their large size and their ability to move incredibly fast while also being frequent makes the danger of them colliding in service really severe, and the importance of keeping them apart while in service also very critical. And this is why we have signaling, a number of underappreciated and incredibly complex technologies that allow us to achieve this. Signaling helps keep the world moving, and by the end of this video you should have a pretty good understanding of it. Let's get going because we have a lot to talk about. If you're not already, consider supporting the channel on Patreon. It helps a lot and makes us so we can cover all kinds of transport topics, including signaling. I fancy myself a quite passionate transit observer, analyst, or connoisseur, but what I'm not is a signaling expert. So I asked Tyson Moore, who is an actual signaling expert, to come on and talk about signaling with me today. Tyson actually has degrees in this stuff, including from the University of Birmingham in the UK. He also has really passionate opinions about all things signaling and train control. So before we dive into the nitty-gritty of ETCS, ATP, KVB, ATB, and PZB, signaling people really love their acronyms, perhaps we should discuss what signaling actually is. Thanks, Reese. Signaling exists to allow trains to operate in a railway in a safe way without going too fast, going in the wrong direction, or trains getting too close to each other. All signaling systems essentially work on the principle of providing instructions to trains, which allows the trains to then operate spaced apart. There are many different ways to do this. You can separate the train into fixed blocks and make sure that there's only one train in one block at one time. This is called fixed block signaling, and it's what most passenger and freight mainline railways use. Or you can create a buffer space around every train and make sure that those trains don't get too close to each other. This is called moving block signaling and is usually used on high-capacity metro lines. Many signaling systems also include train protection, which can stop a train if it's going too fast or too far. Sometimes this is done electronically, but it can also be done mechanically with something as simple as a train stop and a tripcock on board a train. Now you might have noticed that some rail systems don't have real signaling. TTC streetcar anyone? And that's because for low-frequency routes, or routes where the trains don't go particularly fast, it's not actually necessary. Most trams are able to stop in the distance that a driver can see in front of them, so it's not actually necessary to have fixed signals. But just because you don't see signals beside a track doesn't mean that there's no signaling in use. This is the case with modern communications-based train control, or CBTC, which is often used on metro lines. Or it could be what signaling engineers call dark territory, which isn't as spooky as it sounds. It just means that train separation is done procedurally, with a pen, paper, and radio, rather than being done with an electronic system. Now, signaling has quite the storied history. In the 1830s, trains were kept apart by railway policemen holding a stopwatch and a flag, and this was all done on one-directional lines. In the late 19th century, signalers in signaling cabins on the side of rail lines would use a combination of telegraphs and semaphores to send trains down the line. In the 1920s, electrical system with colored light aspects started to appear, but things don't appear to have changed so much since then, right? Answering this question requires us to consider why and how signaling systems have continued to develop even since the fundamental electronic and logical foundations were laid. Fundamentally and historically, signaling systems have grown more complex over time, while at the same time increased traffic, more infrastructure, and railway traffic has led to far more infrastructure risks being present. The complexity of signaling systems comes from the number of components required, from the signals themselves, track switches, interlockings that make sure conflicting routes don't happen, radio towers, train detection like track circuits or axle counters, all need to work together to form a signaling system. Now naturally, with so many challenges in developing signaling, locales that wanted high performance and interoperable train networks worked together to develop a set of standards, as well as interoperable systems to simplify the way that signaling was deployed on the railway. Well, at least one did, and this gave us the de facto standard in global modern railway signaling, E-T-C-S. In the 1980s and 90s, European regulators realized they had a real problem on their hands. There were over 20 incompatible signaling systems being used across the European Union, meaning that trains on the trans-European rail network would need to switch signaling systems every time they crossed an international border, which was complex, inefficient, and very expensive. The European Rail Traffic Management System, or ERTMS, was designed to address this problem of interoperability while improving safety and capacity. There are three technologies that fall under the ERTMS umbrella, the most important of which is the European Train Control System, or E-T-C-S. The way E-T-C-S works is pretty simple. Trackside equipment tells the train information about the track it's on, like speed limits, how steep the track is, and most importantly, the train's position. Since all the information comes from the wayside, you don't need a big database of every rail line in Europe loaded into the train, unlike some positive train control or PTC systems in the US. This information comes from bright yellow eurobalises attached to the sleepers, which we'll look familiar if you've been on the Toronto subway in the past couple years. Or, if you're the Wuppertal Schwebebahn, the belises are mounted on top of the guideway at a 45 degree angle. They're normally unpowered and use radio waves to communicate with the train. It's like if you could tap your credit card at 500 kilometers an hour. The train receives periodic updates about where it's allowed to go, which is called a movement authority. This can either come from belises linked to an existing signalling system, or over a radio connection. The European Vital Computer, or EVC, yep, every component starts with euro, continuously calculates the maximum speed of the train based on the train's properties, like the weight and its braking ability. This way, the EVC can make sure that the train always stops by the end of its movement authority. This is part of what makes ETCS so adaptable to different types of trains, whether it's a light tram train or a fully loaded freight train. Despite its name, today, ETCS is deployed in over 50 countries, on all six currently inhabited continents. I'm also pretty sure the Antarctica's would choose it if they actually had any railways. What's even better is that ETCS equipment from different manufacturers all works together. In Denmark, the country is split in half, with wayside systems from Alstom in the east and from Tallis in the west. In the Netherlands, Alstom and Bombardier trains, which were manufactured before they were just one company, operate over HSL's with Siemens' wayside equipment. This interoperability is incredibly powerful. ETCS may sound great, but there's one big problem, complexity. There are dozens of independent subsystems that need to work together so that the train operates smoothly. Much of the work that I do centers around communication systems that are used with ETCS. One of those is called GSM for Railways, or GSMR, which will be obsolete around 2030. If you want to see a video about GSMR and its replacement, leave a comment down below. Now there are other challenges holding ETCS back, especially on lines where train throughput is incredibly important. One of these challenges is known as train integrity, which is essentially making sure the back of the train is still attached to the front. Now this is pretty straightforward with multiple unit trains like we so often talk about, but it gets a lot more complicated when you're talking about freight for example. Another really important challenge for Railways is adapting to the digitalization of infrastructure. In other words, there are computers everywhere now. Railways love to install a piece of equipment, leave it for 50 years, and then remove it at the end of its life. But as we all know, our phones and computers are receiving updates all the time. If there's an update to your phone that changes the way it works, Android 12 anybody, it can be really frustrating, but updates to these critical systems can pose safety and reliability risks. Software bugs and knee signaling systems for Crossrail have been a major source of delay for the project, as you've probably heard. Because of those signaling bugs, integration won't actually happen on day one. And we know that some of them won't be resolved for the opening of the line on May 24th. The complexity of modern software makes it much more complicated to troubleshoot signaling systems, especially compared to mechanical or electrical systems that you can directly observe. ETCS is the key to improving interoperability, safety, and efficiency for railways, not just in Europe, but around the world. That said, it's only one piece of the signaling puzzle. That's all from me. For more about railways and signaling, check out pantograph.ca, or follow me on Twitter, at Tysmo. If you'd like to see more videos and content on signaling and all things transit, make sure to check out the links down below for more from Tysen, as well as making sure you're subscribed to RM Transit for all the latest content. Thanks for watching, and we'll see you in the next one.