The roll-out of automated point heaters in Switzerland offers a case study showing how industrial IoT technology can help rail operators improve efficiency and reduce costs even as traffic increases.
For operators and infrastructure managers alike, reliability is the watchword of the modern railway. As freight and passenger numbers grow, pressure from policymakers and stakeholders is focused increasingly on keeping routes open while delivering steadily improving trends in on-time operations. In many mature markets, the regulatory regime means penalties can be levied for late or cancelled trains, meaning that operators and infrastructure managers have an interest in managing reliability. In addition, a raft of other metrics must also be kept under review, covering fundamentals from staff safety through to carbon emissions.
Data collection is central to ensuring these metrics can be measured and, where necessary, acted upon. Among field assets, the Remote Telemetry Unit is a proven component fitted to track, station, signalling and level crossing equipment. It can collect, store and act upon data, unaffected by its surrounding environment.
RTUs are built to survive in remote, extreme environments, including wide temperature variations and even immersion in water, whilst being able to manage data collection and analysis autonomously, and provide a low latency response to change. From an Industrial Internet of Things perspective, the RTU can live 'on the edge'.
The promise of IIoT
The potential of IIoT has been recognised for some time, and there is clearly immense value in using it to optimise railway operations. This includes detecting impending failures faster and responding to them before they start to impact performance.
The existence of the RTU makes the deployment of IoT concepts for control, monitoring and analysis of railways both logical and viable today. RTUs collect data from sensors at the remote location and process it for an immediate, local response. There is no risk of latency in sending data back to a central server and awaiting a response. This approach also solves the problem of outages caused by a lack of connectivity to a central server; RTUs are autonomous and can maintain local control for extended periods without centralised supervision.
RTUs can also act as data concentrators. Sending every data sample to a main server individually would quickly overload a communications link. Better to minimise congestion by concentrating on transmitting only essential data. For example, an RTU could sample the level of a water tank or the voltage on a power line several times per second for alarm and control purposes, but only send the key details to the main server. Sending a minimum, maximum average, total and standard deviation for a data point each hour, rather than every second sample, reduces communications traffic by 99.9%. This still provides the essential insight into the remote systems even when there is next to no available bandwidth.
Networked point heaters
As an example, Ovarro's TBox RTUs have been seleced by Swiss Federal Railways to monitor the condition of point heaters. Understandably, the local environment features extreme variations in climate, especially in winter, and the railway employs staff at more than 700 locations on call around the clock for clearing snow or ice from switches and crossings.
In an effort to reduce its dependency on manual labour, the track maintenance division decided to install automatically controlled turnout heating systems at strategic locations across the network. Hundreds of individual switches were fitted with small heaters powered by gas or electricity. Using an algorithm based on data from temperature and humidity sensors, ice and snow on the rails can now be detected automatically. A control system then starts the heaters to prevent the build-up of snow or ice on the switch points.
The automated process at each station, yard or junction is managed by a TBox RTU located in a control cabinet. Depending on the complexity and size of the station, one or more remote I/O modules are located in the field to operate and monitor a group of point heaters. These sub-units handle the measurement and control tasks of the individual heaters, and are linked to the RTU control hub via a local telecoms network that can be up to several kilometres in length.
Despite the electrical interference from passing trains, this configuration has proved to be stable. Each sub-unit has its own operating console for maintenance and manual control if necessary, and only one device is required to manage both the communications and the remote control of the heating systems. All of the data captured from the RTUs, including sensor operation, point setting, outside temperature, gas pressure, and present consumption rate, is transmitted to a central hub using SCADA software and a wide-area optic fibre Ethernet network with TCP/IP protocol. For redundancy and safety, each TBox RTU has its own GSM modem that can be contacted directly for maintenance or control purposes. It can also be used to generate e-mail alerts or alarms to GSM mobiles.
Using a programmable device offers significant savings compared not merely to the historic practice of leaving the heaters on all winter, but also compared to the operation by thermostat. The telemetry units have already delivered a rapid return on investment, thanks to the significant savings in electricity and gas consumption driven by automation of the heating system.
Remote control has removed the need for local personnel to clear snow and ice at stations, allowing them to be deployed on other tasks. Meanwhile, the local logging of data on events, energy consumption, temperatures and equipment operating time is proving to be valuable information for the railway's management team.
Looking ahead, improvements in processing power and throughput are allowing the RTUs to keep up with an increasing demand for data. This is especially important in rail applications, where geographically dispersed assets with multiple functions can generate status reports in huge volumes.
The priority is for IIoT tools to be able to capture and interpret data in real-time. This will be the primary focus to be borne in mind as the next generation of increasingly ruggedised RTUs comes to market.