Railways harness greater potential in the cloud
Since the 1800s, when public railways revolutionized transportation, operators have looked for new ways to increase rail efficiency and safety. Their earliest methods, such as mechanical arms used for trackside signaling, look primitive today. Especially when compared with automated, digitalized operations that can provide wide-ranging insights and actions throughout a rail environment.
But the process of digitalizing operations, itself, is still undergoing transformation. And more and more applications used in railways are beginning to run in a cloud environment dedicated for mission-critical rail applications, generally referred as OT cloud. For operators who understand the essentials of combining an OT cloud with a mission-critical communication network spanning the access networks, WAN and the data center, this latest development opens up additional opportunities for increasing agility and resiliency, as well as gaining greater control and interoperability.
For a prime example of how this works, consider recent changes to railway signaling — an aspect of operations that’s essential for safe traffic control and collision prevention.
What is in-cab signaling?
A major evolution in signaling took place not long ago, with the emergence of in-cab signaling, which relies on advanced communication technology, instead of trackside mechanical devices or colored lights. That means it can now give a big boost to railway efficiency and safety by continually exchanging a broad array of information to the train driver — or to the onboard computer in the cab.
This data includes receiving signal information encoded digitally, as well as transmitting operating information, such as train location and speed and the latest track and weather conditions. Much of it is generated by sensors and remote terminal units located beside the tracks, onboard the train and inside stations — then collected in the OT cloud where it can quickly be put to work by SCADA and traffic control system applications. Using this data, digital signaling can make the train driver and on-board computer constantly aware of any status changes in real time, helping to ensure safer rail systems and more robust performance.
However, it’s crucial to keep in mind that the reliability of in-cab signaling depends heavily on a resilient communication network to deliver digital signals. Therefore, an end-to-end communication pathway needs to be carefully designed into the signaling system, with an understanding of the now-crucial data center’s role.
Unlocking network potential: The role of the data center fabric
The diagram below provides a streamlined illustration of in-cab signal flow, based on the European Train Control System (ETCS) architecture. ETCS is the train signaling and control component of the European Rail Traffic Management System (ERTMS). Its goal is to develop an open standards-based, interoperable platform for railways authorities.
The end-to-end data journey of digital signaling
Keep in mind, first of all, that a digital signaling system has three subsystems that communicate with each other throughout the whole train journey. They’re described here, from left to right.
- An on-board computer controls the train’s movement. It has a driver-machine interface showing signaling and other information, such as instantaneous and maximum permitted speeds.
- Radio block centers (RBCs), placed strategically along the track, are responsible for the safety of train movements within the area each RBC controls. They communicate with the train to gather its position regularly and grant movement authority when it is safe to continue along the track. Since RBC uses train-to-ground radio network (GSM-R today migrating to FRMCS in the future), the communication would travel back to the radio core of the wireless system and boomerang to the radio base station.
- A train control system (TCS) application, hosted in the rail operator’s data center, communicates with RBCs to oversee and supervise all train operations in the rail system.
The curvy horizontal lines in the diagram show the flow of signaling traffic among the three subsystems. You can see that data travels through three different network domains:
1) the train-to-ground radio network,
2) the IP/MPLS backbone and
3) the data center network (often called “the fabric”).
When railway operators build communication networks today, high availability is a top priority for the train-to-ground network and IP/MPLS backbone. But fabric redundancy has not been given the same careful consideration, so far. Now, though, the fabric is playing an increasingly important role in operations, because RBCs, interlocking and SCADA are being designed to operate in a virtualized compute environment, running in virtual machines or containers — typically in the OT cloud. In other words, the railway mission-critical network blueprint has gained a new domain, the fabric.
With this transformative change, data center fabric no longer only carries best-effort IT data. It now carries life-critical signaling and control data. Therefore, rail operators need to carefully rethink the data center fabric with network performance reliability considerations in mind, so that it provides 5-nines or even higher availability.
For a more detailed discussion of OT cloud for railways please download our white paper, “Accelerate the digital rail journey with OT cloud”.
