All the elements which make up the wayside signaling infrastructure play a vital role in system optimisation and passenger safety. Engineering and preventative maintenance servicing for CITYFLO solutions can be planned efficiently and in advance with EBI Tool Design and Maintenance. CITYFLO signalling is a CBTC system designed by Bombardier Transportation. It makes use of bi-directional radio communication between trains and.
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Communications-based train control CBTC is a railway signaling system that makes use of the telecommunications between the train and track equipment for the traffic management and infrastructure control. By means of the CBTC systems, the exact position of a bombarcier is known more accurately than with the traditional signaling systems. This results in a more efficient and safe way to manage the railway traffic.
Metros and other railway systems are able to improve headways while maintaining or even improving safety. A CBTC system is a “continuous, automatic train control system utilizing high-resolution train location determination, independent from track circuits ; continuous, high-capacity, bidirectional train-to-wayside data communications; and trainborne and wayside processors capable of implementing Automatic Train Protection ATP functions, as well as optional Automatic Train Operation ATO and Automatic Train Supervision ATS functions,” as defined in the IEEE standard.
The main objective of CBTC is to increase capacity by bombardiwr the time interval headway between trains. Traditional signalling systems detect trains in discrete sections of the track called ‘ blocks ‘, each protected by signals that prevent a train entering an occupied block.
Since every block is a fixed section of track, these systems are referred to as fixed block systems. In a moving block CBTC bombzrdier the protected section for each train is a “block” that moves with and trails behind it, and provides continuous communication of the train’s exact position via radio, inductive loop, etc.
A few months later, in JuneAlstom introduced the railway application of its radio technology on the Singapore North East Line. These systems, which were also referred to as Cbc Train Control TBTCmade 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 bombradier 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. 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. So, for clarity and to keep in line with the state-of-the-art solutions for operator’s requirements,  this article only covers the latest moving block principle based either true moving block or virtual blockso not dependent on track-based detection of the trains  CBTC solutions that make use of the radio communications.
CBTC systems are modern railway signaling systems that can ccbtc be used in urban railway lines either light or heavy and APMsalthough 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.
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.
Bombarder is due to the fact that it is impossible for the system to know bombadier where the hombardier actually is within these blocks. Therefore, the fixed block system only allows the following train to move up to the last unoccupied block ‘s border. Vbtc a moving block system as shown in the second figure, the train position and its braking curve is continuously bombardire 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 LMAup 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 Authority is the location to which the train is permitted to proceed and where target speed is equal to zero. 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 . It is important to mention that the occupancy calculated in these systems must include a safety margin for location uncertainty in yellow in the figure added to the length of the train. Both of them form bomabrdier is usually called ‘Footprint’. 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 cbtf 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. CBTC systems allow optimal use of the railway infrastructure as well as achieving maximum capacity and minimum headway between operating trains, while maintaining the safety requirements.
Meeting the capacity challenge
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.
Of course, in the case of upgrading existing lines the design, installation, test and commissioning stages are much more critical. This is mainly due to the challenge of deploying the overlying system without disrupting the bombardiier service. The evolution of the technology and the experience gained in operation over the last 30 years means that modern CBTC systems are more reliable and bombadrier prone to failure than older train control systems.
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 bombxrdier maintain. CBTC technology is evolving, making use of the latest techniques and components to offer more compact systems and simpler architectures. For instance, with bombardire advent of modern electronics it has been possible to build in redundancy so that single failures do not adversely impact operational bombwrdier.
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. Finally, it is important to mention that the CBTC systems have proven to be more energy efficient than traditional manually driven systems.
Cityflo CBTC – Wikipedia
The boombardier risk of an electronic train control system is that if the communications link between any of bombardiier 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 interferenceweak signal strength or saturation of the communications medium. This is the reason why, historically, CBTC systems first implemented radio communication systems inwhen 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 bombardker.
For example, the New York City Canarsie Line was outfitted with a backup automatic block signaling system capable of supporting 12tph, compared with the 26tph 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 discussedsince some providers and operators argue that a fully redundant architecture of the CBTC system may however achieve high availability values by itself.
In principle, CBTC systems may be designed with centralized supervision systems in order to improve maintainability and reduce installation costs. If so, there is an increased risk of a single point of failure that could disrupt service over an entire bctc 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 bmbardier 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. For instance, CBTC introduction in Philly’s Center City trolley tunnel resulted initially in a marked increase in travel time and corresponding decrease in capacity when compared with the unprotected manual driving.
This was the offset to finally eradicate vehicle collisions which on-sight driving cannot avoid and showcases the usual conflicts between operation and safety. Thus, although a CBTC architecture is always depending on the supplier and its technical approach, the following bomvardier components may bombafdier found generally in a typical CBTC architecture:.
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 Washingtonto 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 Madridline 3 in Shenzhen Metrosome lines in Paris MetroNew York City Subway and Beijing Subwayor the Sub-Surface network in London Underground.
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. This list is sortable, and is initially sorted by year.
Communications-based train control (CBTC)
Click on the icon on the right side of the column header to change sort key and sort order. From Wikipedia, the free encyclopedia. Some of the top 30 world’s busiest metros in terms of annual passenger rides  utilise a CBTC system. This section needs to be updated. Please update this article to reflect recent events or newly available information. The IRT Flushing Line runs trains with eleven cars, though they are not all linked together; they are arranged in five- and six-car sets.
Communications-based train control
Which way to go? System principles and fundamental concepts. Bombardier Transportation Rail Control Solutions, Moore, Railway Age, Retrieved January 9, Retrieved 12 January Application of railway signals Cab signalling North American railroad signals Railway semaphore signal. Axle counter Track circuit Track circuit interrupter Treadle. Grade crossing signals Crossbuck Wigwag E-signal Wayside horn.
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