Railway systems/networks are divided into sections (also known as blocks) to avoid collision between trains; because more than one train is NOT permitted to run on the same section of the track at the same time. The recent train accident in India along with the casualty numbers has warranted to revisit the train signalling system and how technology can come for rescue. The probe report flags multiple protocol breaches including signalling system as reason for the accident (1).
Combination of Blockchain, IoT and AI technology will play a big role in addressing this real-life challenge.
Signalling system plays a vital role in a Railways network to monitors the trains movement and operates the trains in a safe manner. Finding issues with signal failure before time will not save lives and national infrastructure. Key objectives of a Rail signalling system are:
- Maintain a safe distance between trains
- Control the trains movement at junctions
- Prioritise track allotments based on business rules (Fast train vs slower trains vs goods trains)
Internet of Things (IoT) based event logger are being used in many countries to monitor and log the data related to train movements, but many a times this logger is not integrated or overlooked by personnels during the decision making which are primarily manual in nature. Also the usage of IoT systems are limited to predict failure of equipments to alert signal engineer for maintenance rather than using in real-time decision makings.
Problem statements:
In the above diagram, a passenger train has got priority over a goods train. When both the trains approaches a station which is equipped with a “passing loop” track, Peer to Peer (P2P) negotiation takes place. In this case, passenger trains negotiate with Station master to get access to the main line, and good train negotiate with station master to divert into passing loop track. Just imagine when trains are also passing in opposite track at the same time, the station master will get engaged in similar P2P negotiations. Such a P2P coordination can become with more number of trains participating in the network and also if train lines are crossing each other (diamond crossing). The real treat to safety is, the outcome of such a bilateral coordination (P2P) is provisional until all the coordinations are completed (between station master and participating trains).
Concurrent one-to-one coordinations are potentially complex and inefficient or even dangerous if done manually or by unsophisticated approach. All the coordinations between peers must be able to execute the same safeguarding logic that take into consideration of all relevant actors within the given railway network.
Secondly, in some cases it is seen that, once a section of track is allowed to one train post P2P negation, the track fails to switch as intended and hence creating accident situation.
Solution Components:
Blockchain: Blockchain technology provides both centralized and decentralized aspects of a solution.
It will hold the network-wide data at central level which is unique truth and can be shared across all participating nodes (information like train routes, timetables, passenger reservations, infrastructure reservations etc.). It will hold network-wide rules to safeguard trains in terms of smart contracts (stored on the ledger). These are software defined rules and will get executed when certain conditions are met.
The governance will be decentralized, business network administration is based on consensus and on transparency. Transactions are verified (endorsed) and ordered (serialized) by peers/orderers distributed over the participating network. When participating trains in a section or within a defined proximity met certain criteria consensus being taken in defined channel and corresponding smart contracts are verified and ordered for execution. This way, any bottleneck from central broker that is responsible for information distribution is avoided.
Internet of Thing: IoT devices are used to provide real-time situational data from the ground.
Once consensus is arrived in Signalling system for a train to get access to a particular section, the Switch operators makes sure the required switches happens before a green signal provided to the train driver.
So the IoT system will be a participant of the Blockchain system to provide a finality to the transactions before it get executed. IoT devices can be used to monitor the track changes and pass/fail flag will come back to Blockchain system as input before it commits the transaction. Computer vision/ camera solutions can be also used alternatively.
The status of the signal (green or red) on a particular track can be easily broadcasted by a wireless transmitter to any near-by approaching train. This come handy especially early morning hrs with less visibility where train driver need not have to look for the signal outside, but will get the status inside the driver cabin itself.
IoT devices using RFID and other technology can be used to build Anti Collision Systems for railway which can sense static or slow moving objects on the track. Indian railway has been using Train Collision Avoidance System in certain sections of the network successfully (2).
Conclusion
The Blockchain-based signalling System will be a software defined safety mechanisms that can be considered to automate train traffic management. Exponential technologies such as Edge Computing, 5G, IoT and AI can be used to bring right capability for implementation of such a system.
Blockchain and IoT solutions together will provide the real time data to all the stakeholders including Station Masters, Section Controllers, Signal Engineers and others. By sharing real time data on train movement with data integrity and transparency in place, this solution will enhance decision making capability. All the participating trains can communicate with each other, and decisions will be executed through smart contract that can avoid train delays which typically happens due to information gap and lack of trust with the existing systems.
Data will be stored in a distributed ledger using cryptography which will ensure data integrity and tamper proof. Applications and user interfaces can be build on Blockchain system to authenticate participants (driver, dispatcher, station master) based on face recognition or similar technology to avoid security risks.
References:
- Indian Express (2023, 5 July). Probe report flags multiple protocol breaches for Bahanaga Bazar crash. https://www.newindianexpress.com/states/odisha/2023/jul/05/probe-report-flags-multiple-protocol-breaches-for-bahanaga-bazar-crash-2591586.html
- India Times (2022, 3 April). Explained: How Railways’ Indigenous Anti-Collision System Kavach Can Prevent Train Accidents. https://www.indiatimes.com/explainers/news/indian-railways-indigenous-anti-collision-system-kavach-565956.html