The system can handle a mixture of on-street and segregated driving. Train detection is fundamentally performed by loops with optional track circuits where needed or possible. Point machines can be either street type or railway type. This is a modern computer-based control and supervision system allowing the operator to give commands through a mouse or keyboard with the facility to have the position of the vehicles and optional wayside objects shown on both, normal display screens and large rear projection screens. EBI Screen also provides train regulation for the system. EBI Lock computer-based interlocking The CITYFLO system does not normally have interlockings in non-segregated or street areas where driving takes place on sight, but might have interlockings in segregated areas where the driving takes place under railway conditions.
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Since every block is a fixed section of track, these systems are referred to as fixed block systems. A few months later, in June , Alstom introduced the railway application of its radio technology on the Singapore North East Line.
These systems, which were also referred to as transmission-based train control TBTC , made use of inductive loop transmission techniques for track to train communication, introducing an alternative to track circuit based communication. This technology, operating in the 30—60 kHz frequency range to communicate trains and wayside equipment, was widely adopted by the metro operators in spite of some electromagnetic compatibility EMC issues, as well as other installation and maintenance concerns see SelTrac for further information regarding Transmission-Based-Train-Control.
As with new application of any technology, some problems arose at the beginning mainly due to compatibility and interoperability aspects. Moreover, it is important to highlight that not all the systems using radio communication technology are considered to be CBTC systems. Main features[ edit ] CBTC and moving block[ edit ] CBTC systems are modern railway signaling systems that can mainly be used in urban railway lines either light or heavy and APMs , although it could also be deployed on commuter lines.
In the modern CBTC systems the trains continuously calculate and communicate their status via radio to the wayside equipment distributed along the line. This status includes, among other parameters, the exact position, speed, travel direction and braking distance. This information allows calculation of the area potentially occupied by the train on the track. It also enables the wayside equipment to define the points on the line that must never be passed by the other trains on the same track.
These points are communicated to make the trains automatically and continuously adjust their speed while maintaining the safety and comfort jerk requirements. So, the trains continuously receive information regarding the distance to the preceding train and are then able to adjust their safety distance accordingly. Safety distance safe-braking distance between trains in fixed block and moving block signalling systems From the signalling system perspective, the first figure shows the total occupancy of the leading train by including the whole blocks which the train is located on.
This is due to the fact that it is impossible for the system to know exactly where the train actually is within these blocks. In a moving block system as shown in the second figure, the train position and its braking curve is continuously calculated by the trains, and then communicated via radio to the wayside equipment.
Thus, the wayside equipment is able to establish protected areas, each one called Limit of Movement Authority LMA , up to the nearest obstacle in the figure the tail of the train in front. Movement Authority MA is the permission for a train to move to a specific location within the constraints of the infrastructure and with supervision of speed.
End of Movement is the location to which the train is permitted to proceed according to an MA. When transmitting a MA, it is the end of the last section given in the MA. This safety margin depends on the accuracy of the odometry system in the train.
CBTC systems based on moving block allows the reduction of the safety distance between two consecutive trains. This distance is varying according to the continuous updates of the train location and speed, maintaining the safety requirements. This results in a reduced headway between consecutive trains and an increased transport capacity.
The grades of automation available range from a manual protected operation, GoA 1 usually applied as a fallback operation mode to the fully automated operation, GoA 4 Unattended Train Operation, UTO. The higher the GoA, the higher the safety, functionality and performance levels must be. These systems are suitable for the new highly demanding urban lines, but also to be overlaid on existing lines in order to improve their performance.
This is mainly due to the challenge of deploying the overlying system without disrupting the revenue service. CBTC systems normally have less wayside equipment and their diagnostic and monitoring tools have been improved, which makes them easier to implement and, more importantly, easier to maintain. For instance, with the advent of modern electronics it has been possible to build in redundancy so that single failures do not adversely impact operational availability.
Moreover, these systems offer complete flexibility in terms of operational schedules or timetables, enabling urban rail operators to respond to the specific traffic demand more swiftly and efficiently and to solve traffic congestion problems. In fact, automatic operation systems have the potential to significantly reduce the headway and improve the traffic capacity compared to manual driving systems. Risks[ edit ] The primary risk of an electronic train control system is that if the communications link between any of the trains is disrupted then all or part of the system might have to enter a failsafe state until the problem is remedied.
Depending on the severity of the communication loss, this state can range from vehicles temporarily reducing speed, coming to a halt or operating in a degraded mode until communications are re-established.
If communication outage is permanent some sort of contingency operation must be implemented which may consist of manual operation using absolute block or, in the worst case, the substitution of an alternative form of transportation.
System redundancy and recovery mechanisms must then be thoroughly checked to achieve a high robustness in operation. With the increased availability of the CBTC system, there is also a need for extensive training and periodical refresh of system operators on the recovery procedures.
In fact, one of the major system hazards in CBTC systems is the probability of human error and improper application of recovery procedures if the system becomes unavailable. Communications failures can result from equipment malfunction, electromagnetic interference , weak signal strength or saturation of the communications medium.
This is the reason why, historically, CBTC systems first implemented radio communication systems in , when the required technology was mature enough for critical applications.
This is usually more of an issue with applying CBTC to existing transit systems in tunnels that were not designed from the outset to support it. With the emerging services over open ISM radio bands i. Such decision would help standardize CBTC systems across the market a growing demand from most operators and ensure availability for those critical systems.
As a CBTC system is required to have high availability and particularly, allow for a graceful degradation, a secondary method of signaling might be provided to ensure some level of non-degraded service upon partial or complete CBTC unavailability. For example, the New York City Canarsie Line was outfitted with a backup automatic block signaling system capable of supporting 12 trains per hours tph , compared with the 26 tph of the CBTC system.
Although this is a rather common architecture for resignalling projects, it can negate some of the cost savings of CBTC if applied to new lines. This is still a key point in the CBTC development and is still being discussed , since some providers and operators argue that a fully redundant architecture of the CBTC system may however achieve high availability values by itself.
If so, there is an increased risk of a single point of failure that could disrupt service over an entire system or line. Fixed block systems usually work with distributed logic that are normally more resistant to such outages. Therefore, a careful analysis of the benefits and risks of a given CBTC architecture centralized vs. When CBTC is applied to systems that previously ran under complete human control with operators working on sight it may actually result in a reduction in capacity albeit with an increase in safety.
This is because CBTC operates with less positional certainty than human sight and also with greater margins for error as worst-case train parameters are applied for the design e. This was the offset to finally eradicate vehicle collisions which on-sight driving cannot avoid and showcases the usual conflicts between operation and safety. Architecture of a CBTC system The typical architecture of a modern CBTC system comprises the following main subsystems: Wayside equipment, which includes the interlocking and the subsystems controlling every zone in the line or network typically containing the wayside ATP and ATO functionalities.
Depending on the suppliers, the architectures may be centralized or distributed. The control of the system is performed from a central command ATS , though local control subsystems may be also included as a fallback. Train to wayside communication subsystem, currently based on radio links. This subsystem is in charge of the continuous control of the train speed according to the safety profile, and applying the brake if it is necessary.
It is also in charge of the communication with the wayside ATP subsystem in order to exchange the information needed for a safe operation sending speed and braking distance, and receiving the limit of movement authority for a safe operation.
Onboard ATO system. It is responsible for the automatic control of the traction and braking effort in order to keep the train under the threshold established by the ATP subsystem.
Its main task is either to facilitate the driver or attendant functions, or even to operate the train in a fully automatic mode while maintaining the traffic regulation targets and passenger comfort.
It also allows the selection of different automatic driving strategies to adapt the runtime or even reduce the power consumption. Wayside ETCS system. This subsystem undertakes the management of all the communications with the trains in its area. Additionally, it calculates the limits of movement authority that every train must respect while operating in the mentioned area.
This task is therefore critical for the operation safety. Wayside ATO system. It is in charge of controlling the destination and regulation targets of every train. The wayside ATO functionality provides all the trains in the system with their destination as well as with other data such as the dwell time in the stations. Communication system. The CBTC systems integrate a digital networked radio system by means of antennas or leaky feeder cable for the bi-directional communication between the track equipment and the trains.
ATS system. Its main task is to act as the interface between the operator and the system, managing the traffic according to the specific regulation criteria. Other tasks may include the event and alarm management as well as acting as the interface with external systems. Interlocking system. When needed as an independent subsystem for instance as a fallback system , it will be in charge of the vital control of the trackside objects such as switches or signals , as well as other related functionality.
In the case of simpler networks or lines, the functionality of the interlocking may be integrated into the wayside ATP system. Projects[ edit ] CBTC technology has been and is being successfully implemented for a variety of applications as shown in the figure below mid They range from some implementations with short track, limited numbers of vehicles and few operating modes such as the airport APMs in San Francisco or Washington , to complex overlays on existing railway networks carrying more than a million passengers each day and with more than trains such as lines 1 and 6 in Metro de Madrid , line 3 in Shenzhen Metro , some lines in Paris Metro , New York City Subway and Beijing Subway , or the Sub-Surface network in London Underground.
Projects are classified with colours depending on the supplier; those underlined are already into CBTC operation [note 1] Despite the difficulty, the table below tries to summarize and reference the main radio-based CBTC systems deployed around the world as well as those ongoing projects being developed.
Besides, the table distinguishes between the implementations performed over existing and operative systems brownfield and those undertaken on completely new lines Greenfield. List[ edit ] This section needs to be updated. Please update this article to reflect recent events or newly available information. July This list is sortable, and is initially sorted by year. Click on the icon on the right side of the column header to change sort key and sort order.
Bombardier Wins Contract to Provide Melbourne’s First High-Capacity Signalling System
Since every block is a fixed section of track, these systems are referred to as fixed block systems. A few months later, in June , Alstom introduced the railway application of its radio technology on the Singapore North East Line. These systems, which were also referred to as transmission-based train control TBTC , made use of inductive loop transmission techniques for track to train communication, introducing an alternative to track circuit based communication. This technology, operating in the 30—60 kHz frequency range to communicate trains and wayside equipment, was widely adopted by the metro operators in spite of some electromagnetic compatibility EMC issues, as well as other installation and maintenance concerns see SelTrac for further information regarding Transmission-Based-Train-Control. As with new application of any technology, some problems arose at the beginning mainly due to compatibility and interoperability aspects. Moreover, it is important to highlight that not all the systems using radio communication technology are considered to be CBTC systems. Main features[ edit ] CBTC and moving block[ edit ] CBTC systems are modern railway signaling systems that can mainly be used in urban railway lines either light or heavy and APMs , although it could also be deployed on commuter lines.
Meeting the capacity challenge
Kakazahn Moreover, it is important to highlight that not all the systems using radio communication technology are considered to be CBTC systems. The main objective of CBTC is to increase capacity by reducing the time interval headway between trains. The information needed from the track for the normalization of position errors is passed to the train through norming point balises located in the middle of the track at certain points. The information needed from the track for the normalization of position errors for the system is passed to the train through norming point balises located in the middle of the track at various points. It makes use of bi-directional radio communication between trains and wayside equipment, as well as true moving block technology, to control train operation. EBI Com bpmbardier block centre. Communications-based train control — Wikipedia The system is used for automatic running of trains on segregated tracks.
Communications-based train control
System Hardware 1. SMC remote terminals at other locations on the wayside 5. Snoopers 7. The communication between different subsystems can be through wired media copper or fibre optics e. It maintains the moving block separation of trains, ensures the required routes are followed, oversees the train operation and provides all necessary functions to support automatic operation of trains.
CBTC BOMBARDIER PDF
Since train-to-wayside communication is provided via two-way radio, the exact position of the trains is known at every moment. In addition, the CITYFLO solution can be used as an overlay radio-based train control system to upgrade existing fixed block systems. The system is used for virtual block semi-automatic running of trains STO on segregated tracks and has the potential for upgrading to a driverless system. Wealth of experience Bombardier is a market leader in CBTC technology with our moving block CITYFLO solution in delivery or in operation on 40 lines globally, from automated people movers to fully automated, high-capacity lines. Anchor : Wayside Wayside components All the elements that make up the wayside signalling infrastructure play a vital role in system optimization and passenger safety.