Skip to main content

What You Need to Know Before Your Next Rail Monitoring Project

The following is a transcript of What You Need to Know Before Your Next Rail Monitoring Project. Slides can be found here.

Speaker: Marko Ravnjak, Applications Engineer, Trimble Geospatial Monitoring

Hi, and thank you for joining. In this video, I'm going to be talking about things you need to keep in mind before your next rail monitoring project.

As we know, a lot of resources are being invested in climate-friendly ways of transport. Moving traffic from the road to the rail is one of the ways to fight climate change. And because of that, there's a lot of construction happening in the rail environment to support that initiative, whether that's new construction or reconstruction as part of infrastructure renewal. 

So with that, demand for monitoring is growing as well. In this video, you will get a better understanding of rail monitoring and the things that you need to know before your next rail monitoring project.

t4d rail monitoring intro slide

Before we start, I'm going to share a little bit about me and my background. My name is Marko Ravnjak. I live in Munich, Germany, and I hold a Master's Degree in Geodesy and Geoinformatics. I'm experienced in construction surveying from my time working at a construction company, STRABAG. In addition to this, I’ve been involved in rail surveying and rail surveying project management during my time working for Deutsche Bahn, a German national railway company. At Trimble, I've been focusing on monitoring solutions as an Application Engineer since 2022.
In this video, we’ll start by talking about what exactly rail monitoring is and why it is important in today's environment. 

After that, we will discuss things to know for a successful rail monitoring project. We'll finish with the key things to consider when selecting the software solution for rail monitoring purposes.

agenda slide what you need to know for next rail monitoring project

What is rail monitoring and why is it important 

If we're looking at different rail directives from around the world, we're going to see different descriptions of rail monitoring as a term and what exactly is considered in the category.

Here, I've selected five descriptions. One is from the USA, and the others are from Australia and Europe. We will take a deeper look to see what falls under the umbrella of rail monitoring. So let's break this down.

rail monitoring definitions

The first directive I came across talks about monitoring the rail infrastructure object. This is a broad term that summarizes the whole rail infrastructure itself.

Similarly, the following directive mentions technical and natural objects extending the scope to cover a wider range of elements linked to the rail system, including both technical components and natural surroundings.
Moving on, the next two directives are more specific and focus on track geometry monitoring. And lastly, the fifth directive emphasizes track condition. Here, the focus shifts to evaluating the overall condition of the track. This includes various factors such as wear and tear, geometry and other elements critical to track health.

Now if we take a deeper look, we're going to see that these definitions also tell us what the main goal of rail monitoring is. This can span from the capture deformations of infrastructure objects to the determination of movements, deformations and hazards to ensure the integrity and maintenance of track conditions within the limits.

So even though these definitions vary when compared to each other, it's clearly stated what has to be monitored. Whether that's track geometry for other rail infrastructure, like stations, catenary masts, bridges and tunnels and similar. The aim remains the same here and that is to ensure safe train operations keeping the passengers safe and ensuring safety in general in the rail environment.

This is where rail monitoring plays a key role.

rail monitoring and safety slide

The reasons for these changes can vary and can be caused by several key factors. The first, and also the most common, reason why a monitoring system is being installed in the field, is construction. 

Construction involves activities carried out directly on objects like buildings in the station area or platforms. This type of construction can introduce movements that impact other rail infrastructure and, with that, necessitate monitoring to maintain safety. 

Although construction may not directly impact what is happening on the track, it can have an influence on it. Activities conducted near these objects might introduce vibrations, ground movements and shifts that affect the stability or functionality of the rail system. 
So, monitoring these movements during the construction period becomes imperative to prevent potential risks or issues.

Natural events such as landslides or floods also pose significant challenges to rail infrastructure.
These events can result in round shifts, erosion or structural damage, which compromises the safety and reliability of the railway network. Rail monitoring in such areas helps to enable proactive measures to reduce risks and ensure continued safe train operations.

Climatic events, such as drastic temperature differences between summer and winter, also play a role in impacting rail infrastructure. Extreme temperature variations can cause expansion or contraction of materials, potentially leading to track misalignment or other structural issues. Monitoring for these changes is crucial to identify vulnerabilities and implement timely maintenance and corrective actions.

So now that we know what rail monitoring is, let's talk about the things to know for a successful monitoring project.

Things to know for a successful monitoring project

things to know for your next rail monitoring project

I listed in this slide the main things to keep in mind. However, depending on the project you're dealing with, this can vary. Today, we're going to be talking about these in more detail, starting from directives—project specifications and requirements.

Then we will talk about the monitoring area, discuss sensors and measuring procedures, parameters and thresholds and then alarming reporting and the responsibility when defined thresholds are reached.

rail monitoring directives slide

So starting with directives. 

If you have directives, defined by the rail authority, in your country, you're probably familiar with this term. If not, make sure you do so before your next rail monitoring project.

On the right-hand side, I listed four examples of these. On the top, we have one directive from SBB from Switzerland. Under that, one from Germany, Deutsche Bahn. Then we have Network Rail UK, and at the bottom, we have project requirements defined by Amtrak in the USA.

These documents establish minimum requirements for measurement and evaluation of monitoring in the rail environment. And if you remember definitions from the last slides, this can mean different things. It can be rail geometry but also different technical and natural objects.

They are valid in specific countries or regions and basically give you more or less all the information about how to do rail monitoring from sensors that can or must be used, deliverables, responsibility and so forth. So, as mentioned, if you're coming from a country that has defined directives—specifically for monitoring—you will find everything you need there.

rail monitoring when you have no directives slide

When there are no directives that define your monitoring procedures, there still may be project specifications, which will—in a slightly smaller scope than directives—tell you the things that are valid for a specific rail monitoring project.

Based on project attributes, it will tell you which sensors have to be used, what has to be calculated, how long the monitoring will take and so forth.

In the last case, when there are no project specifications, and you have more freedom in setting up the project yourself, you have to start by asking yourself these questions. 

  • What kind of movement is expected and where?
  • How can necessary data be collected? 
  • And how often is data collection necessary? 

So, as we dive in more and talk about zones of influence, talk about sensors, etc., I hope you will be able to answer these questions when you come across a rail monitoring project.

rail monitoring when you have no directives slide

As we continue through the presentation, I'm going to be focusing more and more on rail geometry since this is one of the most common elements to be monitored when we talk about rail monitoring and also, most importantly, when it comes to ensuring safe traffic.

Speaking of which, knowing how to predict the area that is affected or the so-called “zone of influence,” is key to successfully catching the changes in rail geometry. This is something you have to define before you go into the field and install your sensors. 

If this is not defined in the directives, it's always a good idea to talk with the professionals in the geodetic, geotech, construction and rail fields to get a full understanding of how, for example, nearby construction can affect the track. When this is known, extend that area by dozens of meters to ensure you are covered.

The monitoring grid is the next thing. 

What is the distance between sensors in the field installed on so-called cross-sections? This will, in most cases, be the basis for parameter calculation. For example, the twist base is closely connected with the train wagon's wheelbase. Keep this in mind when you plan your sensor grid.

sensors slide rail monitoring

The sensors you choose to use in the field depend on a variety of different factors. For example, how often do you need your results? Are we talking about relative or absolute data? Which area are you planning to cover? How is the weather situation in the field? These are just a few examples.

Once you have these questions answered, either by looking into the directive or by going into the field and checking the situation yourself, you will be able to decide upon your go-to data collector.

Total stations, for absolute data and tiltmeters, for relative rail monitoring are the most common ones. Having both is also an option, and we see customers doing this for redundancy reasons. You'll hear a lot about this option when you discuss rail monitoring with someone.

I listed some other data collection options on the right-hand side. We have a digital level for the 1D semi-automated approach, tilt beams to get information about uniformity to the vertical plane, fluid meters for dynamic twist monitoring and so forth. All of these are not always necessary, but they can bring additional value and important pieces of information during rail monitoring.

measurement codes rail monitoring

The measurement procedure is closely related to those questions you should have before starting the project.

In this case, I'm going to focus on the two most common sensor solutions for rail monitoring, total stations and tiltmeters.

So depending on how often measurements should be taken and how often and for how long the track can be accessed, you will decide on collecting the data manually or automating measurements.

Let's say 120 meters of track have to be monitored the stakeholder needs the results on a bi-weekly basis. If you have free access to the check, you might go into the field every second Friday and survey the track. In this case, you will be doing semi-automated or so-called campaign-based or manual monitoring. 

But if there is a lot of traffic happening near the track, or for some other reason, it's not easily accessible, it makes more sense to set up an automated monitoring system. Not only will you have additional resources that can be invested somewhere else, but you will also increase the data flow and lower reaction time with real-time alarming.

The next question is, what kind of result is required?

If the track surveying data—which includes coordinates of the rail, cant, gauge, and station information—also called as-built data of the track, is necessary and available, you could calculate absolute results. In this case, monitoring prisms are being measured, as usual, but parameters are calculated using the actual coordinates of the rail. The as-built data, as well as survey data, is used to get from the measured prism to the rail. And this is what is meant here with absolute data. 

I'll give you one example: twist expressed in per mile. 

Without as-built data, we can only calculate twist from prism elevation, which is not a real representation of how the track is actually twisted. Using as-built data, we calculate the twist using the elevation of the actual rails, and we can then calculate and see that the absolute twist value is, for example, two and a half per mile, where the absolute threshold may not allow the track to be twisted more than three and a half per mile. 

Without as-built, we could only see how much the twist value has changed since the monitoring started, i.e., since the reference measurement, and this is meant by the relative results. 
So, if you have to monitor absolute parameter values, you will also have to survey the track to have that starting as-built data. 

If you only require relative results, total station monitoring without as-built survey data or using tiltmeters is an option where relative change is being recorded.

rail geometry parameters

So what should be monitored? 

Rail, or track, geometry itself is described with horizontal and vertical alignment, cant (height difference between the rails) and gauge (the distance between two rails).  

Designing rail geometry is a high-level engineering process where speed, driving dynamics, train size, weight, surroundings and so forth play a key role.

Once designed and documented, the goal is to build it accordingly in the field and to keep it in that state as long as possible. But of course, with so many outside influences, geometry is going to change.

Now, horizontal and vertical alignment can be described in geometry parameters. 

Two other parameters are twist (this tells us how twisted the rail is) and versines (inner geometry of the track), or in other words, variations in the track's horizontal and vertical position over a certain distance called chord length.

And finally, we have displacements, which are simply changes in track position and elevation when compared to the reference measurement. 

The goal of rail monitoring is to make sure the parameters mentioned are within the limits, and thresholds will be described in the directives or defined by the project stakeholders.

The parameters for what should be monitored vary from region to region and project to project. 

Some questions to answer before your project starts are: 

  • Are you calculating parameters for the track centerline (for example, displacements and versines), which represent uniform track position and elevation? 
  • Or are you calculating those parameters for both rails?
  • Is it an automated monitoring system?
  • Are you using prism coordinates or rail coordinates? In other words, do you have your as-built data?

Different parameters can also have different units, like twist for example. Twist is a parameter that can be expressed in per mil, mm or as a gradient.

Make sure you have these answered before you set up your system. 

alarming reporting and responsibilities in rail monitoring

In the world of rail engineering, real-time alarming is a game changer. It helps ensure that stakeholders get the information they need to implement swift actions where needed.

Clear definitions and protocols for real-time alarming, before a monitoring project begins, provide stakeholders with the ability to determine an appropriate response. 

This real-time alarm operates on a foundation of defined thresholds, and these thresholds act as crucial checkpoints, alerting us when parameters change beyond the accepted safety margins. 

So when an unwanted change occurs, the first question is who bears the responsibility and for what. Assigning clear responsibilities and actions to specific individuals, or teams, is imperative for a quick and coordinated response to any changes detected in the rail geometry.

A structured reporting schedule is pivotal. 

The frequency at which reports are generated and what information needs to be delivered in the report depend on the project and infrastructure being monitored. 

Setting up effective real-time alarming, based on defined thresholds, demands clear responsibilities, prompt actions and structured reports for access to data. 

Key considerations for software solution selection

software selection for rail monitoring

The last thing to consider before starting your rail monitoring project is the software solution. In the best-case scenario, you will utilize one platform that meets all of your project needs. 

You should ask yourself: 

  • Can either an automated or semi-automated, campaign-based monitoring, approach be supported in the software?
  • What is the most urgent data I need from the software? 
  • In the case of absolute data being necessary, how can I get that survey data into the software to be able to calculate absolute values using coordinates of the rails? 
  • Which parameters can I calculate? 
  • How is the data visualized? 
  • What are the deliverables? 
  • How can I share the data? 

For me personally, the important thing is also to understand how big the learning curve is. 

Not everybody monitoring for rail is a rail surveying expert. However, everybody doing rail monitoring projects should be able to understand and analyze data from the software.

Manual work should be avoided since it can lead to mistakes being made.

And with that, I'd like to thank you for watching. I hope you found it interesting and learned a thing or two. To join our email list to learn more about rail monitoring solutions, complete the form below. 

Curious to learn more about rail monitoring?

Sign up for our email list!