If you've got a question that we've not yet covered then please contact our team for assistance.
We grouped our FAQ in several sections:
Laser light pulses being sent along fiber optic cables is common. From internet and phone to TV services, it is an integral part of most digital communications systems. Our DAS systems use an eye safe laser source known as a Class 1 laser. These make our sensing units inherently safe and lowers health and safety precautions for their use as it eliminates the need for safety interlocks and physical keys to operate the equipment.
As we are using light pulses through a glass fiber, we also do not generate electromagnetic interference, which is another key concern for railway engineers, to ensure electromagnetic compatibility and avoid any interference with signalling or other safety critical systems.
We don’t currently provide a SIL rating for our monitoring systems. We provide information to railway staff, not a safety control system for their operation. We keep humans in the loop to make the key decisions but improve their information, insight and situational awareness. We deliver information to people not commands.
Our systems are providing information to operators rather than taking direct control, so ultimately a human takes a view on the best way to act on the information presented to them. We hold ISO27001 Certification to minimise cybersecurity risks and the sensing unit is CIS Benchmark compliant.
To tamper with the sensing fiber signals you must get physical access to it, which is part of what our security application is monitoring anyway.
DAS systems are designed to monitor vibrations and movements, not to capture personal data, thus minimising privacy concerns.
Generally anything that makes a loud sound or vibration in contact with the ground near where the fiber is buried is detected.
Correctly classifying those sounds to tell you what made the vibration is more complex. To date we can automatically classify events and details such as: Train position, people walking, manual digging, mechanical digging, cable movements and tampering, vehicles intrusion, electrical arcing/flashovers, rockfalls, landslides, and more. We are always looking for new services to offer, so please contact us with your enquiry or question and we’ll see if it is feasible. Our 4 key monitoring services are Track Condition, Landslide and Rockfall, Security monitoring, and Catenary flashover location.
No – not if it is on the same length of fiber. One sensing unit supports all current applications if you want more than one application in the same area. Each unit has a maximum length of fiber it can monitor (up to 100km), and all applications can be run on the same fiber at the same time.
If you need coverage in a different section of track, (on a different fiber), or outside the 100km fiber coverage of the first unit, then yes, you’ll need an extra sensing device to monitor that route/region. We’ll work with you to find the optimal configuration for your track requirements.
Yes, DAS can detect unauthorized movements along the railway, alerting operators to potential security breaches. Here is a 3 minute recorded live demo video on an operational railway.
Yes, DAS can detect ground vibrations from seismic events. Whilst seismology isn’t something we specialise in, DAS is used to study earthquakes. We tend to be listening for smaller more localised ground movements such as rockfall and landslides. However, if there is a customer demand for earthquake detection, then it is something we would be prepared to evaluate as it is certainly something we can detect.
Yes! There are two main types of vehicle intrusion. Intentional and accidental. The first is detected in a similar way to detecting trespassers on track by tracking a vehicle moving or idling close to the rail track. Accidental intrusion is usually detected in a similar way to detecting falling rocks or landslides, i.e. an impact of heavy objects near to the track. Here is an example of where DAS technology could have prevented a car accident becoming a rail accident.
Yes, although it does depend on the animal size and number. We are currently delivering elephant detection for several hundreds of kilometres for Indian Railways as an example.
Yes. DAS can monitor changing vibration levels generated by rail traffic, helping to mitigate noise pollution in urban areas such as that caused by rail corrugation. Contact us for more information.
A location accuracy of +/- 10m along the fiber length is typical.
How would you like to be alerted? We provide alerts via a variety of methods depending on your preference. We provide web dashboards, API integrations, text messages, e-mails and even sirens for some users. We’ll work with you to deliver the best solution for your needs.
Our algorithms monitor data in real time. The time to get an alert depends on how you have chosen to receive alerts. E.g., API and web dashboards are practically instant, but an e-mail or text message might take a several seconds due to external network delays. Alert timings are typically in seconds rather than minutes or hours!
Yes and No. Whilst it is technically possible in specialist DAS applications to record the vibrations generated from speech, in a real-life railway environment we don’t, (and can’t) eavesdrop on conversations. A footstep has several orders of magnitude more vibration energy within it than a spoken word and footsteps are typically some of the quietest things we reliably detect. So no, we can’t tell you if your track workers jokes are funny.
This is a complex question, as it depends on many factors, not least what sort of events you wish to detect. Louder/higher impact events, e.g., large rockfalls are detectable at greater distances than smaller events such as footsteps. Generally, people walking within 5m of the fiber are detected. This can be greater in many cases, but we’d need details to advise more definitively. Please get in touch to discuss your needs.
Yes, although it is something we work hard to minimise. The number depends on the length of track and the sensitivity level desired. Contact us with details of what your project requirements and we can give an indication of the levels expected. We have explored the balance between sensitivity and false alarms here.
The largest source of “false alarms” we typically see is track maintenance operations, (which you may argue isn’t truly a false alarm when we are monitoring for people on or near the track!).
Distributed Acoustic Sensing uses fiber optic cables to detect vibrations along their length. The Distributed part of the name is because we don’t just sense vibration of the whole fiber – we also can measure the position where along the fiber that vibration is occurring. Think of it as a 50km string of vibration sensors/microphones. We explain DAS technology in more detail here.
Fiber optic sensing is a collection of related technologies that all use optical fiber as the sensor. There are many different types, one of which is Distributed Acoustic Sensing (DAS), which we specialise in. You can read about the different types of Fiber Optic Sensing here.
There are lots of reasons, but here are a few: It is usually used in security applications or relatively closed industries like oil and gas or defence, it is a covert and rarely seen technology, it’s complicated to explain, and its use in the railway industry is relatively new. We’ve explored in more detail here.
You can see some of the more common uses for DAS here. In short, Military, Defence, Oil and Gas, Research, and Sub-Sea industries are all uses of DAS technology.
There are many reasons to consider DAS:
Consult with experts, conduct a feasibility study and choose a suitable DAS system provider. You are in the right place! Contact our team
Each sensing device has two fiber connections. Each one monitors up to 50km giving a total fiber length capability of 100km per unit. This typically equates to monitoring around 80km of track once route deviations and fiber maintenance loops are included.
No. When looking at Distributed Acoustic Sensing, you can use specialist fibres, but you don’t have to. Our DAS systems are designed to use standard fibers so we can utilise existing cables wherever possible. Specialist fibers can be more sensitive to strain/vibrations for special applications, but our DAS solutions are designed to work with standard telecoms grade single mode fibers.
It depends. If you have good quality fiber installed in the right location, (usually running next to the track either buried or in troughs), with a spare dark fiber, then you can use this existing cable bundle. If you don’t have fiber installed, or it is a long way from what you want to measure, or is of poor quality/high losses, then you may need to lay new fiber. We can advise and test as our sensing devices contain OTDR capability.
No – Putting fiber on the track over the sleepers/ties or rails creates many issues with track maintenance and reliability. Our recommended placement of fiber is running alongside the track ideally below ground level.
Single mode fibers. SMF-28e ITU-T G.652, G.654 or G.655 specification fibers are preferred. If you use an alternative then contact our team who can provide advice.
The two optical connectors on each sensing device are of the E2000-PS APC type.
We are detecting ground vibrations, so direct buried or in cable troughs are typically the most common in the rail environment. Aerial mounting of fiber is generally unsuitable as there is poor coupling of the fiber to ground vibrations, (however in these situations the fiber can still detect airborne vibrations such as those from catenary flashovers).
Despite this being written by a bloke in the UK, we use the spelling that is most familiar to the majority. Even in British English, fiber has been the dominant spelling for the last decade, so we try to consistently use fiber in our writing despite our spellchecker’s best efforts!
The sensing device is a 19 inch rackmount format device 3U in height, so it’s compact.
Height - 132.5 mm (5.22”) / Width - 482.6 mm (19”) / Depth - 453 mm (17.8”)
Two power supply options are available. Both options contain dual redundant power supplies and cables for enhanced reliability.
The first power option is 85 - 264 VAC at 50 - 60 Hz (110V-240V).
The second power option is 16.8 – 62.4 VDC (24-48V).
Maximum power consumption is 110w and the unit is passively cooled (no fans).
The sensing device usually plugs into the local area network (LAN) for data communications. In remote location installations communications can be provided via cellular, satellite, or wireless systems as appropriate to the situation via additional supporting hardware.
End users can receive alert communications via web dashboard, text message and e-mail alerts as appropriate, as well as via API integration of the sensing device to existing alert systems.
Yes. Our applications use AI and machine learning in various ways. We train models using real-railway data and AI can be part of developing the detection algorithms to identify or classify a specific event, reducing false alarms, and to keep our perfomance ahead of competitors!
Yes, these are our own AI models we've trained and built based on petabytes of real rail data. We continue to develop, refine and improve these models to extend their capabilities and the number of uses that DAS has in the rail sector.
Algorithm processing is happening on the sensing device to allow real-time detection of events and sending alerts to the web dashboard. We recently upgraded the sensing units so they could handle more complex and greater numbers of models. Notification emails, SMS messages etc can be sent by cloud services if required. We have a variety of hosting options in terms of on-premises, cloud and edge processing solutions depending on customer needs and data handling policies.
If there is suitable fiber in place, then the installation process can be very quick. Depending on the applications implemented different periods of calibration, zoning etc may be needed, but data gathering can begin virtually immediately (within days). A system can go from “Zero to Hero” in a few days but typically the period of install, tuning and calibration can take from a few weeks to a few months.
Fibers can be direct buried or placed in trackside troughing alongside other cables.
A typical ideal fiber "depth" is 1 to 3 feet (0.3 to 1m). We are looking for a good transfer of vibration from the source to the fiber. If for example you are specifically looking to detect people climbing a fence, then running the fiber along the fence may give the best sensitivity. More typically we are looking for activity near the rail track itself which often has cables running beside it for signalling/telecoms purposes. If we reuse an already existing dark fiber in this location, it makes the project much easier/faster.
We use a single dark fiber to sense vibrations. We don’t currently use in-use / lit fibers.
Power, and fiber access. Ideally, we’d like network/internet access too, but we can provide that if needed in remote locations.
Each sensing device monitors up to 100km (~62 miles) of fiber which translates to around 80km (~50 miles) of rail route. Adding extra devices allows for rapid scaling to monitor and protect entire rail routes as needed.
Coverage depends on many things, but the biggest difference you often see is fiber length and route coverage, e.g., 100km of fiber monitored but 80km of route (62 miles vs 50 miles). Why? It is rare for a fiber to go exactly along the route without any deviations, so we typically allow for 20% of the fiber distance to be taken up with routing around obstacles, into buildings or in and out of cabinets to connect to the sensing device. This allowance also includes fiber maintenance loops to be left at strategic locations. These fiber loops allow for fiber damage to be repaired by removing the damaged area and using extra fiber stored in the loop to avoid having to run new lengths of fiber.
Shining laser light pulses through a glass fiber generates no EMC (Electro-Magnetic Compatibility) concerns. We use an unused (dark) fiber for our detection system to avoid any possible interference with other devices.
We’d need to discuss the finer points, but yes integration into existing systems is possible. Our system can deliver multiple types of output for alerts, e.g., dashboard notifications, email alerts, even SMS messages are requested for some clients. There is an API to feed data into existing operations systems too.
Essentially - None. The fiber is maintenance free so long as it is not physically damaged/cut. The sensing unit which is the heart of our system also requires no routine maintenance, has redundant power supplies, is passively cooled, and is sealed against dust (IP50) for robust reliable service.
No, it is treated and maintained as you would the rest of your fiber network.
Typical lifespan is >15 years, with a Mean Time Before Failure (MTBF) of >131,400 Hours.