At a recent IRSE section event in Birmingham, Tim Lane, principal strategy and innovation manager, Network Rail Telecom (NRT), gave a presentation on Network Rail’s latest innovations in telecommunications and how these may be applied to future deployment on the railway.
To support tomorrow’s railway, communication networks must be able to provide a trackside internet of things (IoT), with real-time data capture to enable ‘predict and prevent’, condition-based maintenance and the ability to add points of presence as and when required. This will enable a condition-based maintenance approach to allow interventions to take place before assets fail, and, ultimately, to automate the interventions. NRT’s strategy is to be in a position to provide universal rail corridor connectivity, to enable trackside IoT wireless connectivity for an ecosystem of low cost, battery-powered intelligent data sensors and things.
Blue skies technology and red signals
After the serious passenger disruption affecting King’s Cross and Paddington station services in December 2014, Francis Paonessa, the then managing director of Infrastructure Projects, Network Rail, carried out a review of the incidents and concluded that “Contractors will be required to test any new equipment in an off-the-railway environment before it is used on live railway work.” This is especially important with new innovative technology.
NRT has developed this requirement into three stages of landing new technologies safely and efficiently. The first stage is to carry out the technology definition, evolution and testing in a specialist laboratory environment, such as the 5GUK R&D hub facility run by a number of universities and known as the R&D stage. Testing then moves to the alpha testing stage with technology proving at the Rail Innovation and Development Centre (RIDC) at Melton Mowbray, Leicestershire in a representative rail environment. Finally, beta testing is carried out via controlled pilot testing and early deployment schemes.
The RIDC site (formerly known as the Old Dalby Test Track) is a dedicated testing and trialling facility for use by Network Rail and the rail industry. It has a 13-mile high-speed electrified test track known as the Down Reversible Line (DRL), and a four-mile low-speed electrified test track known as the Up Reversible Line (URL), where new and modified railway infrastructure, rolling stock, plant and technology is tested prior to operational deployment. The test tracks can be configured as DRL 13-mile, 11-mile or two 5-mile sections which can operate independently. URL can be configured as 2.5 miles (with four-rail DC electric supply) or 4 miles.
It is possible to change the method of operating the test track between multiple operational configurations to offer the best flexibility and accessibility for a range of innovations to benefit multiple industries as well as the rail sector. A two-mile section is non-electrified and well-suited to other testing, such as unmanned aerial vehicles (drones).
The RIDC site has a strong history of helping to develop cutting-edge innovation, which commenced in the late 1960s. Historical events include: the testing of the world’s first tilting train (the APT), early tests of radiating cable propagation in railway tunnels and British Rail’s spectacular collision of a fast-moving train with a nuclear flask. More recently, the site has hosted intensive testing of the S Stock London Underground trains, Intercity Express Programme (IEP), Crossrail and London Overground rolling stock.
Approximately 20km of optical fibre and 3km of copper cable with 11 nodes, along with five trackside and one hill-top radio mast, are now available for telecoms testing. This includes trackside equipment staging and a high capacity internet feed.
Self-managing and self-healing railway
To deliver revolutionary initiatives in rail requires intelligent operations with increasing use of collecting and exploiting live operational data. This will necessitate developing better ways to harvest, transport and process the data. There have already been benefits from the deployment of intelligent infrastructure, with increasing environmental and asset sensing to achieve better availability of actionable intelligence, but more is needed.
The deployment of ETCS and traffic management will deliver increased capability and flexibility, with trains potentially providing service patterns dynamically linked to demand. What rail requires, and customers insist on, is also better predictability and reliability. There needs to be increased automation and autonomy, resulting in a largely self-managing and self-healing railway. All this will require better ways of collecting and processing data, which will need new ways of communicating.
The outgoing president of the IRSE Markus Montigel suggested that the term “Internet of Railway Things” (IoRT) should be used in the context of connected systems contributing to controlling the railway and consisting of networks of devices containing electronics, software, actuators, which allows them to connect, interact and exchange data. Markus said he believed that the new world of connected sensors and actuators, which interact and exchange data – the IoRT – can and must control a lot more in the future than has been possible in the past. Devices must appear en masse and be low-cost in order to fulfil their role.
To achieve this, a telecoms network with new ways of delivering connectivity is required. The Network Rail telecoms network consists of 18,000km of fibre optic cable, 22,000km of copper twisted-pair cable and 2,500 GSM-R radio sites, with a further 3,500 data nodes. All this provides a great basis for connectivity, but innovation is required to exploit this asset even further. The good news is that much of the telecoms innovation is already taking place at the RIDC, which provides a location for NRT and partners from industry to develop and test concepts, without affecting the operational railway.
Fibre-optic sensing
Fibre-optic sensing can be used to measure various external parameters along a fibre-optic cable laid alongside a rail route. Light is reflected or backscattered as it propagates through an optical fibre in response to a change in temperature, a bending or pulling force, or mechanical waves in the fibre’s proximity, which is sensitive enough to detect noise. The backscattered light is detected at the source, and the location and cause of the backscatter event can be determined. In very simple terms, the fibre cable can be considered to be a very long microphone.
Ten years ago, Network Rail deployed a system using fibre optic sensing to detect copper cable theft. Expectations were high and the sales people from the telephone company involved did a good job of selling the idea to the board. Unfortunately, the system suffered from too many false positives, with heavy freight trains triggering alarms as well as trespassers lifting troughing lids. The system was funded as a copper cable theft deterrent system and not as an innovation and development scheme. It did help to prevent one theft, but eventually it was recovered and forgotten about.
Ten years later, the technology has improved, but so also have the expectations and NRT recognises that such systems need to be properly trialled and evaluated, rather than looking for quick wins.
The systems now deployed in trial are effectively delivering a trackside ‘microphone’ fibre-sensing capability approximately every 10 metres, so a 50km fibre is the equivalent of 5,000 distributed sensors. Each acoustic event has its own signature and so far over 60 (and counting) potential use cases have been identified. These include wheel flat detection, earthwork failures, train integrity/derailment detection, rail integrity, trespass, and weather detection.
Over 1Tb of data per day per 20km is collected, so it is a bit like trying to find a needle in a haystack. Techniques are being developed to create reliable, actionable intelligence using a variety of intelligent data and event characteristic detection sources, together with machine-learning technology.
The system has recently been used to track different types of trains running along the RIDC test track while, at the same time, a system provided by OptaSense detected earthquakes at Swansea (17 February 2018) at a magnitude of 4.4 at a depth of 7.4km, 240 km away, and at Grimsby (9 June 2018) at a magnitude of 3.9, depth 18km, 100km away. It was found that the earthquake signal is best detected in areas where fibre-cable makes good contact (coupling) with the ground.
In the immediate aftermath of the derailment of the Down Virgin Trains Pendolino at Grayrigg on 23 February 2007, the damage to the adjacent Up line ‘dropped’ a track circuit and caused a southbound Virgin Cross Country Voyager train to stop at a protecting red signal. Had the Up line been monitored using axle counters, the southbound Voyager could have probably run into the derailed Pendolino at high speed, causing a much worse incident. Many of the worst rail accidents have involved a second train running into a derailed train.
Track circuits would not always detect a derailed train and, with many routes now equipped with axle counters for train detection (which are unable to detect a derailed train). Could fibre optic sensing provide a solution?
Chris Gibb, non-executive director of Network Rail, recently told Rail Engineer: “I am always amazed at what falls on the railway, almost by chance. In my time I’ve experienced a skip lorry, ready-mix concrete lorry, light aircraft, small boat, balloons, containers, some bridges, tunnel parts, fencing, telegraph poles, numerous trees and cars, freight wagons and coal.”
It’s early days yet, but one day there may well be a network of fibre sensors to monitor and allow interventions to be instigated to prevent collisions and keep the railway safe.
LoRaWAN
Long Range Wide Area Network (LoRaWAN) is a standard for wireless communication that allows IoT devices to securely communicate over large distance with minimal battery usage. It has a similar range to a mobile phone with the flexibility of Bluetooth or Wi-Fi and a battery life measured in years. LoRaWAN is designed for small sensors/devices/things that are battery operated and communicate limited information intermittently. It is therefore ideal for key IoRT requirements such as bi-directional communications, end-to-end security, mobility and low power.
There are two different keys in LoRaWAN to provide security. The network session key (NwkSKey) is used to encrypt the whole frame, including headers and payload. When data is sent, this key is used to sign the message and allows the network server to verify the identity of the sender. An application session key (AppSKey) is then used to further encrypt the payload within the frame.
The unlicensed industrial, scientific and medical (ISM) radio spectrum band is used and, with the system capable of relatively long-range coverage providing connectivity solutions in areas impacted by poor mobile network coverage, it is ideal for non-frequent low-speed railway communication applications. NRT, with the help of Comms365, has already deployed LoRaWAN at RIDC for trial applications of trackside sensing for water level and rail temperature monitoring, and has gained a good understanding of the range and quality of service delivery capabilities.
Use cases could include metering – for example sending several messages a day about current usage; smart lighting; environment monitoring for sound, temperature, pollution, water level, fuel level, vibration and movement; asset management to check the status and location of various assets, access control and level crossing gate status.
Project VECTOR
For lineside applications that require more data bandwidth than LoRaWAN can deliver, and for better trackside coverage, Project VECTOR has been established, which stands for Value Engineered Communications Technology On Rail. This is intended to exploit the 22,000km of lineside twisted-pair copper cables, traditionally used for lineside telephony, such as the signal post telephones (SPT).
In domestic locations, and for some businesses, high speed data internet access is provided via similar copper cables to those used in rail, and very-high-bit-rate digital subscriber line (VDSL) technology. Traditionally, all telephones were powered from the telephone exchange via a central battery, but for high speed data a local power supply is required for the data router. This is why in the event of a power outage home fixed telephones will still work, but internet connections and cordless phones will not, unless a separate battery power supply is available.
Project VECTOR will provide a power supply to a local data modem router via the same twisted pair copper cable, VDSL or symmetrical high-speed digital subscriber line (SHDSL) technology providing equal transmit and receive (i.e. symmetric) data rates. With GSM-R sites located every few kilometres trackside to provide a power supply, it may be possible to provide a high-speed data connection at most locations along the railway. Trials at RIDC involving Nokia and Kenton have suggested that a symmetrical bandwidth of 12Mbits/s with a latency less than 3 milli seconds over a 3km link may be possible.
So, in the 21st Century, can the traditional signal post telephone (SPT), which is still provided as a back up to GSM-R, be replaced with a Wi-Fi point at the signal, allowing drivers to call a signaller via a Wi-Fi voice-calling app on a smart phone? The Wi-Fi point could also provide a high-speed data connection to manage and monitor other trackside equipment, which may include firmware updates to equipment. Could the SPDT (signal post data transmitter/receiver) replace “SPT” in railway terminology to become a 21st century SPT (C21SPT)?
Other use cases could include a fixed telephone via a micro filter for SPTs at key locations and level crossings in addition to a Wi-Fi point, a data connection to a layer 2 data switch or fibre driver, or as a low-powered supply to another operational asset. Could a data Wi-Fi point or a layer 2 data port on a signal be used as part of the Combined Positioning Alternative Signalling System (COMPASS) as back-up degraded mode recovery to conventional signalling?
5G rail testbed
To support the next generation of digital infrastructure, including 5G and full fibre broadband, the Department for Digital, Culture, Media and Sport’s (DCMS) 5G testbeds and trials programme is part of the government’s £740 million National Productivity Investment Fund (NPIF) initiative.
Innovator access to a mainline rail environment, with high speed trains running and infrastructure challenges (including tunnels and cuttings), is near impossible to offer on the operational infrastructure. So, as part of the programme, DCMS has funded the creation of a 5G rail testbed at the RIDC that, to be as accessible as possible, is open for both rail and non-rail 5G testing.
The trackside infrastructure includes antenna support structures, optical fibre, equipment accommodation and power supplies at over thirty locations along the test track, which have been located to support the full complement of 5G spectrum bands and reflect the challenges of trackside rail deployment. The site also includes an operational train workshop, which can support test train installation with supervision, support, guidance and safety certification services.
The telecoms network is at the centre of the future connected railway. While innovating in the rail environment is always a challenge, RIDC Melton is setting itself up to play a key role in safely landing new technologies, such as 5G and fibre-optic sensing.
