Urban population densities are increasing and transit operators are demanding more from their transit infrastructure to reduce headways and increase throughput.
Unfortunately, technology and signalling philosophies developed in the 19th and 20th centuries are not meeting that challenge.
As a result, rail automation is gaining steam. Over the past 30 years, transit operators are shifting to semi or fully automated signalling systems.
The benefits of automation are clear: reduce human error, increase safety, reduce maintenance and increase operational performance but, this comes with a cost in terms of complexity and price tag.
Therefore, how does a transit operator decide how much automation is enough automation for their property?
Experienced CBTC Transit Operators keep a laser focus on their diagnostic design because the time it takes for the Operator to identify a problem, localize the problem and fix it is determined by the diagnostics capabilities of the CBTC solution.
Sophisticated diagnostics enable the Operator to recovery from failure quickly whereas rudimentary diagnostics delay recovery while commuters are stuck on the track.
Given that all railroad properties are under constant maintenance, creating a safe corridor for workers at track level, while maintaining service through the work zone is a critical concern for Operators.
In a CBTC application, work zones take on greater importance because the trains are either driverless or operating in an automated mode with a train Operator. If a CBTC train enters an area with workers, the train will not stop; it will continue to move at the same speed. There must be a vital mechanism to inform the CBTC system of workers at track level.
Operationally critical functions must be understood when deploying a CBTC solution. These functions define how a railroad operates once the solution is deployed and if neglected the Operator can expect service disruptions, longer recovery times and irate commuters. Laser-focus on the CBTC solution’s operational functions will ensure that the operational requirements of the Operator are satisfied.
Fallback mode in a CBTC application, is a legitimate mode of operation but avoid it when possible. The cost of implementing a fallback mode will outweigh the marginal benefits that fallback will provide: increased complexity, increased maintenance cost and up to 30% increase in capital costs. Yet some operators handcuff their solution by imposing a fallback mode requirement without understanding the need.
The operating environment ultimately determines if fallback mode is required and which of the multiple options is selected. The operator must take a methodical approach when evaluating the need for fallback because the consequence of making the wrong decision are costly.
Basic GoA2 automation is the ability to control propulsion and braking based on the conditions of the track ahead. Achieving GoA 2 level of automation is a significant accomplishment but it is not enough for a modern urban transit system. The next step is to increase the level of trackside/platform awareness and control, which brings us to the next Grade of Automation, GoA 3.
