Modern signalling underpins future of rail

Urban rail operators are continually faced with competing priorities. On the one side, there's the need to innovate and improve performance and on the other, is the need to control costs. There's usually trade-offs to be made with less than ideal outcomes, and that's why technology advancements like Communications-Based Train Control (CBTC) are so important. 

CBTC balances competing demands by simultaneously enhancing performance and reliability, improving safety, lowering energy use, and reducing operating costs. This blog explores the benefits of this modern signalling solution, including the potential savings for rail operators. 

What is CBTC? 

CBTC is an alternative to traditional fixed block signalling that provides a more accurate view of train positions and speeds by using widely available mobile communication technologies. The precision offered by CBTC allows rail operators to reduce headways, introducing more trains in the network and therefore transporting more people, more quickly without compromising safety. 

CBTC was pioneered by Thales, and our SelTrac™ CBTC solution has been installed on more than 100 metro lines in 40 cities around the world. SelTrac™ G7, the latest generation, builds on Thales’ leadership and expertise in this space. It offers several features to help rail operators maximise capacity and manage growth. These include: 

Reliable performance above 100kph 
Reduced headways as low as 1 minute between trains
Energy efficient acceleration and braking, reducing a train’s energy consumption by up to 20 per cent  
Flexibility to operate with any telecommunication system, including LTE 
Rolling stock agnostic  

Purpose-built solution eliminates need for secondary-train detection 

One of the key advantages of Thales SelTrac™ G7 is that it avoids the need for secondary train detection systems. This is because  SelTrac™ was designed from the beginning as a completely different type of signalling system to replace fixed block signalling systems. Let’s take the example of what happens when a trains loses communication. With Thales SelTrac™ G7, the non-communicating train’s last reported position is recorded and displayed via the Automatic Train Supervision (ATS)  A protective envelope is formed around the train— and other trains are prevented from advancing into it, until the issue is resolved.  

In comparison, other CBTC solutions in the market, have been developed as an overlay to existing fixed block systems, which means secondary train detection is still required. This approach provides a fallback system, under conditions when there are failures to any of the primary CBTC subsystems.  The issue with these fallback systems is that they significantly increase overall signalling costs and make projects much more complex to design and implement. They also impose a significant maintenance burden and come with more wiring and more equipment, ultimately requiring more space in the equipment room.  

Of course, some may argue that secondary detection with track circuits is worthwhile because it can help to detect broken rails. However, the risk of broken rails can be more effectively managed with a systematic approach to rail condition monitoring. 

For anyone debating the need for secondary train detection, all of this and more is covered in the Thales white paper “Do you really need a fallback system with Communications-Based Train Control (CBTC)?”. The paper can be can downloaded here.

A cost-effective and sustainable solution

By eliminating the need to set up a fully-specified fallback signalling system, rail operators can save approximately five percent of the total cost spent on a greenfield signalling solution. They can also avoid the maintenance costs of such a solution. Generally, secondary detection increases maintenance costs by around a further five percent. 

There are other significant cost savings associated with CBTC and Thales SelTrac™ G7 in particular. As mentioned earlier, SelTrac™ G7 offers energy efficient acceleration and braking which can reduce a train’s energy consumption by up to 20 percent. This is not only good for the bottom line, but good for the environment and will help rail operators to build more sustainable networks. 

Thales can help rail operators achieve further savings by ensuring efficient energy use by the on-board control system and providing tools to enable the creation and optimisation of efficient schedules. 

Thales’ CBTC solution can also help rail operators to optimise revenue. For example, months after deploying Automatic Train Operation (ATO) with SelTrac™ on New York City’s busy Flushing Line, on-time performance improved to 91 percent, up from 74.7 percent before the system was fully deployed.

Similar benefits have been achieved by rail operators all over the world, including Santiago, Doha and Dubai. You can find details of these deployments on our metro site where you can also learn more about Thales’ end-to-end metro system offering, including SelTrac™ G7.

For more information about Thales’ data-driven metro solution, visit our content hub here.