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From page 4... ... SECTION 4 4 CBTC Technology 4.1 CBTC Equipment As defined in FTA Report No. 45, CBTC is a train control system "using two‐way communications between intelligent trains and wayside computers. An intelligent train is defined as a train that can determine its own location and that calculates and enforces safe operating speeds without the use of track circuits or wayside signals. In CBTC systems, the exact position of a train is known more accurately than with track circuit‐based signaling systems. CBTC systems also offer opportunities for improved safety and operational performance, in addition to reduced life cycle cost." From the definition of CBTC comes the four primary components: • Train‐borne equipment • Wayside equipment • Data communications equipment • Automatic Train Supervision (ATS) equipment 4.1.1 CBTC Train‐Borne Equipment CBTC train‐borne equipment consists of one or more processor‐based controllers, associated odometry and data communications devices, and location determination sensors. It interfaces with major train subsystems, wayside, and the ATS equipment via the data communications equipment. It is responsible for train location determination, the enforcement of permitted speed and movement authority limits, and other allocated train‐borne automatic train protection (ATP) Read the entire page →
From page 5... ... SECTION 4 – CBTC TECHNOLOGY 5 4.1.4 CBTC ATS Equipment CBTC ATS equipment includes equipment installed at the control center and/or wayside locations. This equipment handles ATS (non‐vital) functions such as identifying, tracking, and displaying trains, providing manual and automatic route setting capabilities, regulating train movements to maintain operating schedules, and initiating temporary speed restrictions and work zones. ATS also interfaces with other systems such as passenger information systems which indicate when the next train is arriving at a station. 4.2 CBTC Train Control Modes Modern CBTC can operate on several different levels of automation and control modes, typically tailored to specific preferences of a given operating agency. The level of control ranges from full automatic to manual operation with protection. This section discusses commonly adopted control modes of CBTC equipped trains. 4.2.1 CBTC Control Modes The following are the most common CBTC control modes: Full automatic operation Whether fully driverless operation or with an attendant present onboard, the CBTC onboard system controls all operations, including train movement and door operation. No manual intervention by attendant is necessary for normal operations. Partial automatic operation An onboard attendant manually initiates train movement by depressing a start button. Upon validation of required departure conditions, the onboard controller controls the train movement until the next stop. The next stop might be in between stations, behind other trains, or at the next station platform. Manual driving under CBTC protection An onboard driver manually controls the train movement while the CBTC system provides ATP, including speed enforcement. The driver uses the master controller of the train to control the propulsion and brake systems. 4.2.2 Non‐CBTC Control Modes The following non‐CBTC control modes apply to an individual train and not necessarily to several trains. The behavior of the following train is not dependent on the control mode of a train. When the train in non‐CBTC control mode is localized by the CBTC system, the following train can close up to it, as if the non‐CBTC control mode train were in CBTC mode. Manual driving at slow speeds without CBTC protection (Restricted Speed mode) Read the entire page →
From page 6... ... SECTION 4 – CBTC TECHNOLOGY 6 Manual driving without CBTC protection (bypass mode) When operating in bypass mode, the attendant has full control of the train, with no speed enforcements by CBTC. Operation is in accordance with the STD/PS, if there is one available. Otherwise, this mode is for recovery and emergency train movement. 4.2.3 Other CBTC Control Modes Yard operation Where yards are under CBTC control but not fully automated, train movements can be performed by manual driving under CBTC protection or manual driving at slow speed without CBTC protection. Manual driving without CBTC protection – out of CBTC territory Upon detection that the train has left the CBTC territory, an onboard controller may be able to switch over to manual mode without the manual intervention by the driver. The train control consists of manual driving without CBTC protection. Manual driving under civil speed enforcement To mitigate the effect of CBTC system failures or because of a particular CBTC design in some areas of the line, the non‐communicating onboard controller may operate in a type of degraded mode, still capable of enforcing civil speed limits. 4.3 Trends in CBTC Projects Around the World The CBTC technology has evolved over the past four decades, mainly due to an increasing demand for alternatives to address aging signaling infrastructure and to achieve better operational performance. In addition to greenfield applications, many existing mass transit operations were forced to re‐signal legacy infrastructure. Thus, over the past decade, brownfield projects surpassed the amount of greenfield applications. CBTC brownfield projects currently represent the majority of the CBTC applications (except in Asia) Read the entire page →
From page 7... ... SECTION 4 – CBTC TECHNOLOGY 7 The axle counters are commonly used on brownfield CBTC type projects to facilitate migration from legacy systems to CBTC, as those can be fitted and operated independently of existing track circuits. This eases the conversion process and thereby minimizes the risk of service disruptions. The industry opts for reduced levels of STD/PS functions Deploying a CBTC system, especially in a brownfield project without interrupting passenger revenue service, is very challenging. Despite the experience acquired by suppliers over the past decades, there have been examples all over the world of projects being delayed or scaled down. The overall complexity of the system is one of the main reasons for the difficulties to deploy it. Eliminating or minimizing the level of STD/PS is a method to limit re‐signaling project complexity. In addition, there have been projects where CBTC operates very reliably and thereby reduces the real use of STD/PS, though transit agencies still ought to maintain it and bear an upkeep cost. For these reasons, users opt to select an STD/PS with reduced capabilities, able to manage a single non‐ CBTC train but unable to support peak or off‐peak revenue service. Driverless systems are becoming more popular There is a recent trend around the world for driverless systems, either greenfield or brownfield. Driverless systems are less favorable to having STD/PS mainly because of the need to send personnel onboard the train to recover from a failure. Though not all new driverless projects are without STD/PS, one can expect that the proportion of projects without STD/PS will grow along with the progression of driverless projects. CBTC suppliers have limited CBTC experience without STD/PS All industry leading CBTC suppliers have project experience featuring an STD/PS, both with track circuits and axle counters. However, not all suppliers have experience with mass transit projects without STD/PS. There have been only a dozen of such projects without STD/PS in the world. The survey revealed that, to date, all brownfield CBTC projects feature some form of a STD/PS. In other words, only greenfield projects have been implemented without STD/PS so far. Read the entire page →

From page 4...

... SECTION 4 4 CBTC Technology 4.1 CBTC Equipment As defined in FTA Report No. 45, CBTC is a train control system "using two‐way communications between intelligent trains and wayside computers. An intelligent train is defined as a train that can determine its own location and that calculates and enforces safe operating speeds without the use of track circuits or wayside signals. In CBTC systems, the exact position of a train is known more accurately than with track circuit‐based signaling systems. CBTC systems also offer opportunities for improved safety and operational performance, in addition to reduced life cycle cost." From the definition of CBTC comes the four primary components: • Train‐borne equipment • Wayside equipment • Data communications equipment • Automatic Train Supervision (ATS) equipment 4.1.1 CBTC Train‐Borne Equipment CBTC train‐borne equipment consists of one or more processor‐based controllers, associated odometry and data communications devices, and location determination sensors. It interfaces with major train subsystems, wayside, and the ATS equipment via the data communications equipment. It is responsible for train location determination, the enforcement of permitted speed and movement authority limits, and other allocated train‐borne automatic train protection (ATP)

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From page 5...

... SECTION 4 – CBTC TECHNOLOGY 5 4.1.4 CBTC ATS Equipment CBTC ATS equipment includes equipment installed at the control center and/or wayside locations. This equipment handles ATS (non‐vital) functions such as identifying, tracking, and displaying trains, providing manual and automatic route setting capabilities, regulating train movements to maintain operating schedules, and initiating temporary speed restrictions and work zones. ATS also interfaces with other systems such as passenger information systems which indicate when the next train is arriving at a station. 4.2 CBTC Train Control Modes Modern CBTC can operate on several different levels of automation and control modes, typically tailored to specific preferences of a given operating agency. The level of control ranges from full automatic to manual operation with protection. This section discusses commonly adopted control modes of CBTC equipped trains. 4.2.1 CBTC Control Modes The following are the most common CBTC control modes: Full automatic operation Whether fully driverless operation or with an attendant present onboard, the CBTC onboard system controls all operations, including train movement and door operation. No manual intervention by attendant is necessary for normal operations. Partial automatic operation An onboard attendant manually initiates train movement by depressing a start button. Upon validation of required departure conditions, the onboard controller controls the train movement until the next stop. The next stop might be in between stations, behind other trains, or at the next station platform. Manual driving under CBTC protection An onboard driver manually controls the train movement while the CBTC system provides ATP, including speed enforcement. The driver uses the master controller of the train to control the propulsion and brake systems. 4.2.2 Non‐CBTC Control Modes The following non‐CBTC control modes apply to an individual train and not necessarily to several trains. The behavior of the following train is not dependent on the control mode of a train. When the train in non‐CBTC control mode is localized by the CBTC system, the following train can close up to it, as if the non‐CBTC control mode train were in CBTC mode. Manual driving at slow speeds without CBTC protection (Restricted Speed mode)

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From page 6...

... SECTION 4 – CBTC TECHNOLOGY 6 Manual driving without CBTC protection (bypass mode) When operating in bypass mode, the attendant has full control of the train, with no speed enforcements by CBTC. Operation is in accordance with the STD/PS, if there is one available. Otherwise, this mode is for recovery and emergency train movement. 4.2.3 Other CBTC Control Modes Yard operation Where yards are under CBTC control but not fully automated, train movements can be performed by manual driving under CBTC protection or manual driving at slow speed without CBTC protection. Manual driving without CBTC protection – out of CBTC territory Upon detection that the train has left the CBTC territory, an onboard controller may be able to switch over to manual mode without the manual intervention by the driver. The train control consists of manual driving without CBTC protection. Manual driving under civil speed enforcement To mitigate the effect of CBTC system failures or because of a particular CBTC design in some areas of the line, the non‐communicating onboard controller may operate in a type of degraded mode, still capable of enforcing civil speed limits. 4.3 Trends in CBTC Projects Around the World The CBTC technology has evolved over the past four decades, mainly due to an increasing demand for alternatives to address aging signaling infrastructure and to achieve better operational performance. In addition to greenfield applications, many existing mass transit operations were forced to re‐signal legacy infrastructure. Thus, over the past decade, brownfield projects surpassed the amount of greenfield applications. CBTC brownfield projects currently represent the majority of the CBTC applications (except in Asia)

Read the entire page →

From page 7...

... SECTION 4 – CBTC TECHNOLOGY 7 The axle counters are commonly used on brownfield CBTC type projects to facilitate migration from legacy systems to CBTC, as those can be fitted and operated independently of existing track circuits. This eases the conversion process and thereby minimizes the risk of service disruptions. The industry opts for reduced levels of STD/PS functions Deploying a CBTC system, especially in a brownfield project without interrupting passenger revenue service, is very challenging. Despite the experience acquired by suppliers over the past decades, there have been examples all over the world of projects being delayed or scaled down. The overall complexity of the system is one of the main reasons for the difficulties to deploy it. Eliminating or minimizing the level of STD/PS is a method to limit re‐signaling project complexity. In addition, there have been projects where CBTC operates very reliably and thereby reduces the real use of STD/PS, though transit agencies still ought to maintain it and bear an upkeep cost. For these reasons, users opt to select an STD/PS with reduced capabilities, able to manage a single non‐ CBTC train but unable to support peak or off‐peak revenue service. Driverless systems are becoming more popular There is a recent trend around the world for driverless systems, either greenfield or brownfield. Driverless systems are less favorable to having STD/PS mainly because of the need to send personnel onboard the train to recover from a failure. Though not all new driverless projects are without STD/PS, one can expect that the proportion of projects without STD/PS will grow along with the progression of driverless projects. CBTC suppliers have limited CBTC experience without STD/PS All industry leading CBTC suppliers have project experience featuring an STD/PS, both with track circuits and axle counters. However, not all suppliers have experience with mass transit projects without STD/PS. There have been only a dozen of such projects without STD/PS in the world. The survey revealed that, to date, all brownfield CBTC projects feature some form of a STD/PS. In other words, only greenfield projects have been implemented without STD/PS so far.

Read the entire page →

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