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.
The Automatic Train Supervision (ATS) system plays a vital role in monitoring the performance of Communication-Based Train Control (CBTC) signaling systems during revenue operations. Despite its significance, Transit Operators often neglect to properly define the ATS user interface requirements in their specifications, resulting in a CBTC supplier delivering a cumbersome and tedious user experience that is unacceptable for such a crucial subsystem.
GoA 4 is total automation.
At this level, the transformation is complete and the system has taken over the train, wayside and the platforms. Involvement from the operator has been reduced if not eliminated. The operator’s role is to only monitor the system and get involved if there is a failure the automated system cannot handle.
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.
Rail automation is the ability to control train movements without a driver and GoA 2 is the first level that accomplishes this by introducing the core rail automation functionality.
But the jump from #GoA 1 to GoA 2 is an order of magnitude higher than the jump to any other grade (such as GoA 2 to 3 or GoA 3 to 4) due to the complexity and amount of automation required.
Hence, why is the jump to GoA 2 a difficult jump?
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?
The second step in creating a ConOps is to the define the users and understand their priorities by creating a mind map of all frontline personnel.
Identifying users is based on who interacts with the CBTC system. For example, a train driver interacts with the train which is controlled by the CBTC system establishing him as a user.
When some transit agencies being down the path of deploying a CBTC solution, they assume their engineers understand their operational requirements and begin writing a technical specification.
This assumption is wrong.
Frontline personnel (such as train driver or maintenance personnel) understand the daily operational needs of the Transit Agency because they operate the system day in and day out
From a CBTC perspective, a ConOps is written with the end-user in mind and it describes what the transit agency expects from the CBTC system.
The ConOps is concerned with the operating environment where the CBTC system will reside in and where frontline personnel work to deliver service.
The CBTC system must address the needs of these frontline personnel and the purpose of the ConOps is to capture the needs of these workers.
This approach is applicable if the Operator has decided to implement fallback mode of operation and the fallback block design is as operationally efficient as their current block design.
This approach will apply two cutover stages before the full CBTC solution is deployed. The first cutover will switch from the legacy conventional system to the conventional system controlled by CBTC (fallback mode). The second cutover would deploy the full CBTC solution.
The phased cutover approach breaks the track into small pieces and each piece is cutover one section at a time.
Small manageable pieces allow the CBTC solution to mature over time. When the first phase is placed into service, the Operator has a chance to observe the CBTC solution in action for the first time under passenger carrying service.
The cutover from a conventional to a CBTC signalled system is a radical shift for any Transit Operator. New training methods, new maintenance capabilities, new operational procedures; the entire organization changes gears at the same time and this transition is the most vulnerable point for a Transit Operator. At the flick of a switch, the entire organization must switch and the cutover strategy determines how smooth the transition is.
A cutover strategy defines how the Operator will physically switch from their current signaling system (usually conventional) to CBTC.
Predicting a failure before it occurs is the Holy Grail for maintenance personnel and predictive maintenance is the purpose of level 3 diagnostics. Relying on the actual condition of the LLRU to predict when maintenance is required enables maintenance personnel to proactively plan corrective maintenance activities versus the reactive approach of the previous two diagnostic levels.
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.
Equipping maintenance vehicles with a Vehicle Controller (VC) is not a function but a decision and operationally a critical one. Maintenance vehicles must coexist with CBTC equipped passenger trains and therefore Operators have two choices; equip maintenance vehicles and follow consistent operational rules or operate unequipped maintenance vehicles and apply special rules.
Train recovery is a critical CBTC function because it defines how the Operator will recover a failed CBTC train under a worst-case failure. If the CBTC design can handle the worst-case scenario, then all other train recovery scenarios are taken care of automatically.
The Operator has three train recovery options to choose from and this post covers the last 2.
Train recovery is a critical function because it defines how the Operator will recover a failed train under a worst-case failure. If the CBTC design can handle the worst-case scenario, then all other train recovery scenarios are taken care of automatically.
A stranded train due to communication failure is a rare event due to the built-in redundancy all CBTC solutions provide, nonetheless the CBTC solution must have a design in place to recover from this rare event.
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.
