If you’ve ever stood on a railway platform on a misty, rain-soaked day and felt the ground beneath you vibrate with the distant rumble of a train, you’ve experienced a tiny, unspoken role railway fishplates play in keeping that ride smooth—even when wet. As a supplier of railway fishplates, I get asked this question all the time: how do these small, critical metal components perform when exposed to persistent moisture? It’s not just a curiosity; it’s a question that cuts straight to safety, longevity, and reliability for rail operators, track maintenance teams, and anyone who depends on trains getting from point A to B on time. Railway Fishplates
Let’s start with the basics for anyone who doesn’t work in rail infrastructure. Railway fishplates—also called joint bars—are the flat, steel plates bolted to either side of two adjacent rail ends, holding them together to create a continuous rail line. Simple in design, but their job is massive: they transfer the immense weight of trains from one rail segment to the next, absorb the constant hammer of rolling wheels, and keep the track aligned. For decades, we’ve known they do this job best when dry, but real-world tracks almost never stay dry, especially in regions with heavy rainfall, high humidity, or seasonal ice melt.
Over the past 12 years I’ve been supplying fishplates to rail networks across North America, I’ve seen firsthand how wet conditions can shift their performance in ways that surprise even seasoned maintenance managers. Let’s break this down into three key areas: structural integrity, friction and load transfer, and corrosion risk. These are the metrics that matter most, and the ones we test for every batch of fishplates we ship.
First, structural integrity. When a rail is hot, it expands; when it’s cold, it contracts—thermal movement that’s normal for steel tracks. Dry fishplates flex slightly to accommodate this movement, acting as a flexible buffer between two rigid rail ends. But when water gets into the gap between the fishplate and the rail, something changes. Water is far less rigid than metal, so it doesn’t transfer force the same way. In lab tests we run at our in-house testing facility, we’ve measured a 15-20% drop in load transfer efficiency when fishplates are fully submerged in water, compared to identical fishplates under dry conditions. That’s not a trivial number. For a 100-ton freight train, that extra stress has to go somewhere—and often, it puts more strain on the bolt holes or the rail ends themselves, leading to premature cracking.
But here’s the twist: it’s not just standing water that’s a problem. Condensation, the thin, constant film of moisture that builds up on fishplates in humid coastal climates, is even more insidious for structural performance over time. We had a client in the Pacific Northwest a few years back who noticed a 30% higher rate of fishplate failure on their coastal tracks, where salt-laden fog leaves a steady layer of moisture on every component. They initially thought it was just corrosion, but when our team did a tear-down analysis, we found that the thin water film had created micro-slip at the rail-fishplate joint. Every time a wheel passed, that micro-slip caused tiny, repeated stresses that added up quickly. Dry fishplates experience almost no micro-slip, because the metal-on-metal contact creates enough friction to keep the joint aligned. Wet, and that friction drops enough to let those small shifts happen.
Next, friction and load distribution. This is where fishplates earn their keep, especially in wet conditions. When track is dry, the friction between the fishplate and the rail is high, so the load from a wheel spreads evenly across the joint, rather than concentrating on one small spot. But when water or even a light layer of grease (leftover from track maintenance) gets in, that friction drops. We once had a case study with a regional commuter line that started noticing more rail corrugation at joint locations during wet seasons. Corrugation is those small, wavy ridges on rail heads that cause that annoying rumble passengers feel. The root cause? The wet fishplate joints couldn’t distribute load evenly, so each wheel was hitting the joint at the same tiny, high-stress spot thousands of times per day. That accelerated rail wear by 25% in wet months, compared to dry months—costing the line tens of thousands of dollars in extra rail replacement every year.
But it’s not all bad news for fishplates in wet conditions. Modern alloy fishplates we supply, made from high-strength carbon steel with a controlled surface finish, actually perform better in wet conditions than older, low-grade steel fishplates. We did a side-by-side test last year: one batch of our standard high-tensile fishplates, and one batch of generic fishplates from a competitor, both installed on the same stretch of track in Ohio, which gets heavy spring rains. After six months, our fishplates showed zero signs of micro-slip, while the competitor’s had developed 0.8 millimeters of total micro-shift at the joints. The difference? Our fishplates have a shot-blasted surface that creates tiny microscopic ridges that bite into the rail even when wet. It’s a small design tweak, but it’s made all the difference for operators looking to keep joints stable when tracks are soaked.
The third, and most discussed, factor is corrosion. This is where wet conditions really accelerate wear, but it’s not the fishplate itself corroding as much as the joint between the fishplate and the rail. When water gets into the gap between the two, it creates a corrosive environment that eats away at both the fishplate’s surface and the rail’s end. Even worse, when trains pass, the tiny vibrations push the water into that gap, and then pull it out—like a tiny pump, drawing in more moisture and sometimes even road salt or debris from tracks, which makes the corrosion even worse. A fishplate that’s corroded 1-2 millimeters at the bolt holes is 40% more likely to fail under load, according to data from the American Railway Engineering and Maintenance-of-Way Association (AREMA), a group we work closely with to test our products.
But here’s something most people don’t talk about: how fishplate installation affects performance in wet conditions. We’ve seen first-hand that a fishplate installed with a small gap between it and the rail (a common mistake for new maintenance crews) will perform 30% worse in wet conditions, because that gap traps water and never lets it dry out. Conversely, fishplates installed with a slight pre-load, so they sit tight against the rail ends, drain water quickly and keep the joint dry enough to maintain friction. That’s why we include a detailed installation guide with every batch we ship, and we offer free on-site training for large rail network clients—something that’s made our company a go-to for operators looking to cut down on wet-weather track issues.
Over the years, I’ve had clients ask me, “Why not just use welds instead of fishplates? Welds are stronger.” It’s a fair question, but welds have their own problems in wet conditions. If a weld cracks, water gets in and causes corrosion from the inside out, and fixing a broken weld is far more time-consuming and expensive than replacing a single fishplate. Fishplates are modular—you can replace one damaged fishplate in 15 minutes, without needing to shut down an entire track section for hours. That’s a big part of their ongoing value, even when they don’t perform perfectly in wet conditions. The key is choosing the right fishplate for your specific environment. For example, coastal rail lines with high salt moisture need galvanized fishplates or stainless steel alloy fishplates, while lines in temperate climates with regular rain need our standard high-tensile fishplates with shot-blasted surfaces.
Last year, we supplied fishplates to a freight line in Minnesota that handles 120 trains a day, many running in winter conditions where wet snow and ice leave tracks soaked for weeks. The line’s maintenance team had been seeing a 20% higher rate of joint failures each winter, until they switched to our winter-specific fishplates, which have a thicker galvanized coating and a surface texture designed to resist water pooling. After one winter of use, they reported a 85% drop in joint failures, and a 12% reduction in rail wear at joints. That’s the kind of result that makes all the testing and quality control worth it.
Of course, no component is perfect. Even the best fishplates will show wear when exposed to constant moisture over decades. The key is proactive maintenance: checking fishplate torque every three months, cleaning out debris and water from joint gaps after heavy rain, and replacing fishplates when they show signs of corrosion or micro-shift. We work with all our clients to create a maintenance schedule tailored to their track’s conditions, because we know that even the highest-quality fishplates won’t perform well if they’re installed or maintained incorrectly.
As someone who’s spent the last decade and a half working with railway fishplates, I’ve learned that the answer to “how do they perform in wet conditions” isn’t a simple yes or no. It depends on the type of fishplate, the installation quality, the maintenance schedule, and even the specific environmental conditions of the track. What I can tell you is that for operators who invest in high-quality, properly matched fishplates and follow a solid maintenance plan, the performance in wet conditions is more than sufficient to keep tracks safe and on schedule. For those who cut corners on product quality or installation, wet conditions will expose those gaps quickly, leading to delays, higher maintenance costs, and safety risks.
At the end of the day, railway fishplates are one of the unsung heroes of rail infrastructure. You don’t notice them when the sun is shining and the tracks are dry, but when the rain is pouring and trains are rolling heavy, they’re working hard to keep every joint stable, every load distributed evenly, and every train on track. If you’re dealing with wet-weather track issues, or you’re looking to upgrade your fishplate performance for harsher conditions, I’d be happy to walk through your specific needs and share case studies from other lines we’ve worked with. Get in touch to discuss your project, and we’ll help you find the right fishplate solution for your track’s demands.
Composite Sleeper References
American Railway Engineering and Maintenance-of-Way Association (AREMA). (2022). Annual Track Component Performance Report: Joints and Fastening Systems. AREMA Press.
Railway Technical Research Institute (RTRI). (2021). Effects of Environmental Moisture on Railway Track Joining Components. RTRI Technical Bulletin Vol. 47.
International Union of Railways (UIC). (2020). Wet Condition Performance of Steel Rail Joints. UIC Code 710-1.
HENAN GNEE RAIL CO.,LTD.
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