ETCS (European Train Control System) Level 3 has experienced a significant growth in recent times. The fully integrated advanced level train control system does not use wayside signals, as all the information is transmitted using wireless communications. The Level 3 concept has a potential to make a significant impact on the train control systems. Although it will not incur additional capital expenses, the costs incurred towards managing and updating existing assets will count towards operational expenses. While Level 3 is economical to implement, it is critical for rail operators to recognize whether adding capacity gains through ETCS Level 3 will fetch incremental return on investments and simplify the existing issues.
ETCS is the signaling and control component of the ERTMS (European Rail Traffic Management System) developed by EC (European Commission) and ERA (European Railway Agency) to blend ATP (Automatic Train Protection) across numerous European ATP systems. The primary purpose of ETCS was to replace incompatible safety systems used by European railways. Subsequently, this standard has been successfully adopted outside Europe. ETCS supports intercity train traffic within Europe by making the travel simple, comfortable, and economical for passengers and operators.
ETCS is implemented along with the standard trackside and unified controlling equipment within the train. The lineside information is passed to the driver in the train, eliminating the need for lineside signals. ETCS Level 1 is a train signaling system that can be superimposed on the existing signaling system. ETCS Level 2 is a digital radio-based signaling system. The train movement and other signaling aspects are displayed on the onboard computer. However, the train detection, track vacancy, and the train integrity supervision have to be monitored from trackside using radio block center. ETCS Level 3 eliminates the need of track vacancy detection components and operates at fixed intervals. It uses the onboard equipment to obtain short positioning data signals, achieve continuous line-clear authorization, and implement of fixed-block or moving-block operation.
The interoperable architecture and multi-vendor supply market have made ETCS enormously attractive for global rail operators. This led to ETCS becoming a critical standard for ATP on the mainline railways. The only concern with the ETCS is that it is unsuitable for the significant capacity increase as it overlaps with the conventionally fixed block signaling.
CBTC (Communications Based Train Control) is one of the most popular signaling technology for metro rails with high requirements for capacity and performance. CBTC, however, is a supplier- proprietary technology and does not provide interoperability between different suppliers’ products. Less interoperability within metro railways with mostly segregated lines is acceptable, but it is a major problem for large-scale mainline networks that need a multitude of interoperating products for their long-term sustainability.
To address the capacity constraints and because of high expectations for infrastructure savings, the demand for the ETCS – Level 3 is on the rise. Level 3 will be a basis for higher levels of train automation to bridge the gap between CBTC and ETCS. Level 3 technology will enable the adoption of moving block, which means 2-trains in succession can run at lower speeds. It also allows the removal of track-based train detection equipment such as track circuits or axle counters. Additionally, ETCS Level 3 is expected to reduce capital and maintenance costs and improve reliability, optimize train operations, autonomous driving, automatic train regulation, IP radio, and satellite positioning.
With onboard odometers, ETCS Level 3 allows trains to share their location with the TCC (Train Control Center) every 6 seconds. Odometers are reset by balises at equal intervals, and TCC receives movement statuses in return. At present, train integrity is manually supervised by the drivers.
ETCS Level 3 is a priority for ERA, and they are experimenting with interested global rail operators to implement this technology. The railway sector and ERA consider Level 3 as one of the game changers in a competitive and efficient railway system. Although ETCS Level 3 is effective and efficient, the technology is still in the development stages. It must address multiple issues before being implemented into a standard way of operation. It has several issues, but the two main factors that need to be addressed are viz. train should not become uncoupled during the movement and the radio communication should be completely reliable.
The solutions suggested by Level 3 aims to address these two problems and allow the capacity increase, which is the primary requirement at the moment. The core of the proposed system is to retain any existing track-circuit or axle-counter sections and to create ‘virtual blocks’ as sub-sections within the existing architecture.
With the updated features, ETCS Level 3 will experience technical implications. To counter these issues, it is critical to align the balise position and the track-circuit/axle-counter section lengths with each other to ensure that positional information, as displayed to the signal, is the same.
The implementation of hybrid Level 3 concept will significantly impact the train control systems. Although the existing track circuits and axle counters will not incur additional capital expenses, their maintenance and updates will incur operational expenses. While Level 3 is economical to implement, it does not address the impact of radio failures. This requires urgent consideration as it is a problem that equally affects Level 2 unless lineside signals are retained.
Eventually, rail operators should analyze all the factors together and recognize whether adding capacity gains will fetch better return on investments and simplify the existing issues.