Philippe Aretz, Channel Sales Director at Ovarro, looks at how Remote Telemetry Units (RTU) can help rail operators maintain efficiency and safety at a time when passenger numbers are increasing.
A record number of passenger journeys were recorded for England, Scotland and Wales in a recent survey by the Office of Rail and Road. A total of 1.76 billion journeys were completed on Britain's rail network during the 2018-2019 calendar year, a three per cent rise compared to the previous year. These unprecedented numbers of passenger’s place pressure on an already stretched network, meaning maintenance teams are a critical element of ensuring rail assets operate safely and efficiently.
UK travellers who are used to making fast, efficient rail journeys across Europe are often the first to complain about the delays and cancellations when travelling on UK trains. At the same time, Train Operating Companies (TOCs) need to deliver returns on their stakeholders, meaning any disruption or delay can result in lost revenue. An under-performing railway carries a considerable cost for passengers, the public purse and shareholders.
With fines for late or cancelled trains, operators have a vested interest in managing reliability. There is also a need to constantly monitor the environmental impact of any operations and above all else, ensure the safety of staff and passengers. The most valuable technology for meeting these ever more demanding KPIs is 'information'. And the most appropriate device to collect and process this information is the RTU or Remote Telemetry Unit. These devices have a long-proven record of sitting on track, station, signalling and level crossing assets where they collect, store and act upon data, regardless of the surrounding environment.
In effect, RTU's are computers deployed on rail assets. They collect data locally, act upon it immediately, report data to the central control room and maintain a local historical store as an additional backup. The RTU is the device sitting between the Control Room and the Field instruments, which provides a low latency response to changing site conditions as well as performing data filtering. The RTU ensures that only key, critical information is passed via the narrow communications links, minimising data throughput but maximising useful information received.
RTU technology is widely used for track and station assets. The specific types of roles they carry out include power distribution monitoring and control, remote signalling sub system, point and crossing monitoring, track and station condition monitoring as well as passenger information systems. Alongside this, RTUs can provide train/track location system monitoring and control, and driverless train early warning systems.
Case File: Control Switch Point Heaters for Major European Rail Network
The TBox RTUs were selected by a major European rail network to provide point heating condition monitoring. The railway network is located in a country where there are extreme weather conditions and as such, the operator has workers in over 700 railways stations on call around the clock for clearing snow or ice from switch points to prevent them from blocking.
The track maintenance team decided to install automatically controlled heating systems at all strategic locations to reduce the sizeable cost of manpower. In addition, hundreds of switch points were fitted with small heaters powered by gas or electricity. Using a complex algorithm based on data from temperature and humidity sensors, ice and snow on the rails is now detected automatically. A complex PID control system starts the heaters to prevent the build-up of snow or ice on the switch points.
In each railway station, automation is performed by a TBox remote telemetry unit (RTU) located in a control cabinet. Depending on the complexity and size of the station, one or more remote I/O modules are provided as sub-stations in the field to operate and monitor a group of switch point heaters. Via a local RS 485 network that can be up to several kilometres in length, the sub-stations handle the measurement and control tasks of the individual heating systems. Despite the electrical interference from passing trains, automation and communications remain perfectly stable. Each sub-station has its own operating console for maintenance and manual control. Only one device is required for communications and remote control of the heating systems.
All the data (correct sensor operation, set points, outside temperature, gas pressure, present consumption, etc.) from the RTUs is transmitted to a central station using SCADA software and an Ethernet network with TCP/IP protocol. The WAN (wide-area network) uses fibre optics and Ethernet communication. For redundancy and safety, each TBox RTU has its own GSM modem that can be directly addressed for maintenance or control purposes. It can also be used to send e-mails or alarms to GSM mobiles.
The main benefits of the telemetry units for the train operators are that they delivered an extremely fast return on investment due to the significant savings in electricity and gas consumption by the full controlled heating system. Complete remote control of each railway station, eliminating the need for local personnel to clear the switch points, enabled them to be deployed to other tasks.
Latest RTUs provide utmost reliability of the hardware and software components, which was essential due to the extremely harsh environment (high electrical interference, low temperature). In addition, the system allows for local data logging of events and recording energy consumption, temperatures, and equipment operating time, which is proving to be valuable information for the management team. The system provides automatic alarm signalling to key maintenance personnel in charge of the switch points.
In addition to providing safety and reliability, heating systems can realise major savings in energy costs through automation. Using a programmable device like TBox RTU provides significant savings compared to older techniques in which the heaters are either constantly on for the entire winter or operated by a thermostat.
Advances in RTUs
An increased need for efficiency and safety are driving the market for data analysis and monitoring of assets in the rail sector and the previous example illustrates just one practical benefit. RTU's facilitate these processes because they can be deployed on a wide range of assets from track, tunnel, signalling, station or marshalling yard.
Once in place, the real value of an RTU is that it can perform autonomous control in real time, and then report to SCADA that it has everything under control. Operators at the SCADA interface can 'supervise' the operations by setting new KPIs (Set Points) or updating instructions (open/close this, start/stop that or switch on/off - as in the track point heaters, for example) for RTU's to then act upon and manage locally.
The key features needed in any RTU are resilience to the site environment, an ability to operate with minimal drain on local power resources and the processing power to perform any local control algorithms autonomously. It is also beneficial that an RTU has extensive diagnostics capability and a low MTTR (Meant Time To Repair) to reduce the time required for technicians to spend on site, improving both efficiency and personnel safety.
In addition, because RTUs do everything locally, it means if communications break down, they continue to run, maintaining a historical log, and reporting back later. In remote track and tunnel locations this is an essential part of keeping maintenance teams informed and being able to trend data. For example, the data that the RTU collects can be used to support maintenance decisions and to verify that safety obligations are being adhered to. Although most RTUs in the rail network are only used for operations, they can support maintenance teams, Health and Safety initiatives and environmental management. This ability to provide accurate, real time data allows Train operating Companies to make better, more informed decisions. Looking to the future RTUs, which are already 'mini PCs in the field', can transform an aging rail asset into a 'smart' asset. This is possible by fitting an RTU to allow it to trend, interpret and act on data collected from that older asset.
Last but not least, nowadays cyber security becomes a major concern. TBox security becomes a major concern. TBox RTU embeds all features to protect the asset from external attack by using login mechanism, data encryption, firewall, denial of service protection and brute force attack protection.
RTUs continue to evolve, becoming more powerful and as the rail sector looks for more efficient ways to deal with record numbers of passengers, their use looks set to increase. Continued innovation will help drive this change; it is already possible to deploy RTUs on a wide range of rail assets, whatever its size or age. Inbuilt redundancy and resilience are helping, too, avoiding system failures. At the same time, improvements in processing power and throughput are helping RTUs keep up with increasing demand for data.
With its geographically spread assets and multiple process that all generate massive amounts of data, key to ensuring these improvements help performance is being able to capture and interpret it in real-time. Latest, ruggedized RTU technology focuses specifically on that, helping TOCs meet their investor and customer commitments.