Communications-based train control

Communications-based train control is a railway signaling system that uses telecommunications between the train and track equipment for traffic management and infrastructure control. CBTC allows a train's position to be known more accurately than with traditional signaling systems. This can make railway traffic management safer and more efficient. Rapid transit systems are able to reduce 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 functions, as well as optional automatic train operation and automatic train supervision functions," as defined in the IEEE 1474 standard.

Background and origin

CBTC is a signalling standard defined by the IEEE 1474 standard. The original version was introduced in 1999 and updated in 2004. The aim was to create consistency and standardisation between digital railway signalling systems that allow for an increase in train capacity through what the standard defines as high-resolution train location determination. The standard therefore does not require the use of moving block railway signalling, but in practice this is the most common arrangement.

Moving block

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 system 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.
As a result, Bombardier opened the world's first radio-based CBTC system at San Francisco airport's automated people mover in February 2003. A few months later, in June 2003, Alstom introduced the railway application of its radio technology on the Singapore North East Line. CBTC has its origins in the loop-based systems developed by Alcatel SEL for the Bombardier Automated Rapid Transit systems in Canada during the mid-1980s.
These systems, which were also referred to as transmission-based train control, 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 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. However, there have been relevant improvements since then, and currently the reliability of the radio-based communication systems has grown significantly.
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 CBTC solutions that make use of the radio communications.

Main features

CBTC and moving block

CBTC systems are modern railway signaling systems that can mainly be used in urban railway lines and APMs, although it could also be deployed on commuter lines. For main lines, a similar system might be the European Railway Traffic Management System ERTMS Level 3.
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 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. This is due to the fact that it is impossible for the system to know exactly where the train 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.
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, up to the nearest obstacle. Movement Authority 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 an 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 added to the length of the train. Both of them form what 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 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.

Grades of automation

Modern CBTC systems allow different levels of automation or grades of automation, as defined and classified in the IEC 62290–1. In fact, CBTC is not a synonym for "driverless" or "automated trains" although it is considered as a basic enabler technology for this purpose.
There are four grades of automation available:

GoA 0 - On-sight, with no automation
GoA 1 - Manual, with a driver controlling all train operations.
GoA 2 - Semi-automatic Operation, starting and stopping are automated, but a driver who sits in the cab operates the doors and drives in emergencies
GoA 3 - Driverless Train Operation, starting and stopping are automated, but a crew member operates the doors from within the train
GoA 4 - Unattended Train Operation, starting, stopping and doors are all automated, with no required crew member on board

Main applications

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. 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 revenue service.

Main benefits

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 less 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 to maintain.
CBTC technology is evolving, making use of the latest techniques and components to offer more compact systems and simpler architectures. 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.
Finally, it is important to mention that the CBTC systems have proven to be more energy efficient than traditional manually driven systems. The use of new functionalities, such as automatic driving strategies or a better adaptation of the transport offer to the actual demand, allows significant energy savings reducing the power consumption.

Risks

The primary risk of an electronic train control system is that if the communications link between any of the trains is disrupted, 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.
As a result, high availability of CBTC systems is crucial for proper operation, especially if such systems are used to increase transport capacity and reduce headway. 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. In this case, an interruption can result in a service brake or emergency brake application as real time situational awareness is a critical safety requirement for CBTC and if these interruptions are frequent enough it could seriously impact service. This is the reason why, historically, CBTC systems first implemented radio communication systems in 2003, when the required technology was mature enough for critical applications.
In systems with poor line of sight or spectrum/bandwidth limitations a larger than anticipated number of transponders may be required to enhance the service. 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. An alternate method to improve system availability in tunnels is the use of leaky feeder cable that, while having higher initial costs achieves a more reliable radio link.
With the emerging services over open ISM radio bands and the potential disruption over critical CBTC services, there is an increasing pressure in the international community to reserve a frequency band specifically for radio-based urban rail systems. Such decision would help standardize CBTC systems across the market 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. This is particularly relevant for brownfield implementations where the infrastructure design cannot be controlled and coexistence with legacy systems is required, at least, temporarily.
For example, the BMT Canarsie Line in New York City was outfitted with a backup automatic block signaling system capable of supporting 12 trains per hour, 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, since 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 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 must be done during system design.
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. 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. 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.

Architecture

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. 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.
CBTC onboard equipment, including ATP and ATO subsystems in the vehicles.
Train to wayside communication subsystem, currently based on radio links.

Thus, although a CBTC architecture is always depending on the supplier and its technical approach, the following logical components may be found generally in a typical CBTC architecture:Onboard ATP system. 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.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 ATP 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. Additionally, it may also perform auxiliary and non-safety related tasks, for instance alarm/event communication and management, or handling skip/hold station commands.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. The 2,4GHz band is commonly used in these systems, though other alternative frequencies such as 900 MHz, 5.8 GHz or other licensed bands may be used as well.ATS system. The ATS system is commonly integrated within most of the CBTC solutions. 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, 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

CBTC technology has been successfully implemented for a variety of applications as shown in the figure below. They range from some implementations with short track, limited numbers of vehicles and few operating modes, to complex overlays on existing railway networks carrying more than a million passengers each day and with more than 100 trains.

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 and those undertaken on completely new lines.

List

Location/system	Lines	Supplier	Solution	Commissioning	km	No. of trains	Type of field	Grade of automation	Notes
Toronto Subway	Line 3 (SRT)	Thales	SelTrac	1985	6.4	7	Greenfield	UTO	With train attendants who monitor door status, and drive trains in the event of a disruption.
Réseau express métropolitain ''''	A1-4	Alstrom	Urbalis 400	2023-2027	67	212	Greenfield	UTO	Initially opened in 2023, The full 67 km is projected to be opened in 2027
SkyTrain (Vancouver)	Expo Line, Millennium Line, Canada Line	Thales	SelTrac	1985	85.4	176	Greenfield	UTO
Detroit	Detroit People Mover	Thales	SelTrac	1987	4.7	12	Greenfield	UTO
London	Docklands Light Railway	Thales	SelTrac	1987	38	149	Greenfield	DTO	With train attendants who drive trains in the event of a disruption.
San Francisco Airport	AirTrain	Bombardier	CITYFLO 650	2003	5	38	Greenfield	UTO
Seattle-Tacoma Airport	Satellite Transit System	Bombardier	CITYFLO 650	2003	3	22	Brownfield	UTO
Singapore MRT	North East Line	Alstom	Urbalis 300	2003	20	43	Greenfield	UTO	With train attendants who drive trains in the event of a disruption.
Hong Kong MTR	Tuen Ma line	Thales	SelTrac	2020 2021	57	65	Greenfield Brownfield	STO	Existing sections were upgraded from SelTrac IS
Hong Kong MTR	Disneyland Resort line	Thales	SelTrac	2005	3	3	Greenfield	UTO
Las Vegas	Monorail	Thales	SelTrac	2004	6	36	Greenfield	UTO
Dallas–Fort Worth Airport	DFW Skylink	Bombardier	CITYFLO 650	2005	10	64	Greenfield	UTO
Lausanne Metro	M2	Alstom	Urbalis 300	2008	6	18	Greenfield	UTO
London Heathrow Airport	Heathrow APM	Bombardier	CITYFLO 650	2008	1	9	Greenfield	UTO
Madrid Metro	,	Bombardier	CITYFLO 650	2008	48	143	Brownfield	STO
McCarran Airport	McCarran Airport APM	Bombardier	CITYFLO 650	2008	2	10	Brownfield	UTO
Bangkok BTS Skytrain	Silom Line, Sukhumvit Line	Bombardier	CITYFLO 450	2009 2011 2015 2018 2019	64.26	98	Brownfield Greenfield	STO	Upgraded from Siemens Trainguard LZB700M CTC in 2009.
Bangkok BTS Skytrain	Gold Line	Bombardier	CITYFLO 650	2020	1.7	3	Greenfield	UTO
Bangkok MRT	Purple Line	Bombardier	CITYFLO 650	2015	23	21	Greenfield	STO	With train attendants who drive trains in the event of a disruption. These train attendants are on standby in the train.
Bangkok MRT	Pink, Yellow	Bombardier	CITYFLO 650	2021	62.52	58	Greenfield	UTO
Barcelona Metro	,,	Siemens	Trainguard MT CBTC	2009 2010	46	50	Greenfield	UTO
New York City Subway	BMT Canarsie Line, IRT Flushing Line	Siemens	Trainguard MT CBTC	2009	17	69	Brownfield	STO
Singapore MRT	Circle Line	Alstom	Urbalis 300	2009	35	64	Greenfield	UTO	With train attendants who drive trains in the event of a disruption. These train attendants are also on standby between Botanic Gardens and Caldecott stations.
Taipei Metro	Neihu-Mucha	Bombardier	CITYFLO 650	2009	26	76	Greenfield and Brownfield	UTO
Washington-Dulles Airport	Dulles APM	Thales	SelTrac	2009	8	29	Greenfield	UTO
São Paulo Metro	1, 2, 3	Alstom	Urbalis	2010	62	142	Greenfield and Brownfield	UTO	CBTC operates in Lines 1 and 2 and it is being installed in Line 3
São Paulo Metro	4	Siemens	Trainguard MT CBTC	2010	13	29	Greenfield	UTO	First UTO line in Latin America
London Underground	Jubilee line	Thales	SelTrac	2010	37	63	Brownfield	STO
London Gatwick Airport	Shuttle Transit APM	Bombardier	CITYFLO 650	2010	1	6	Brownfield	UTO
Milan Metro	1	Alstom	Urbalis	2010	27	68	Brownfield	STO
Philadelphia SEPTA	SEPTA subway–surface trolley lines	Bombardier	CITYFLO 650	2010	8	115		STO
B&G Metro	Busan-Gimhae Light Rail Transit	Thales	SelTrac	2011	23.5	25	Greenfield	UTO
Dubai Metro	Red, Green	Thales	SelTrac	2011	70	85	Greenfield	UTO
Madrid Metro	Extension MetroEste	Invensys	Sirius	2011	9	?	Brownfield	STO
Paris Métro	1	Siemens	Trainguard MT CBTC	2011	16	53	Brownfield	DTO
Sacramento International Airport	Sacramento APM	Bombardier	CITYFLO 650	2011	1	2	Greenfield	UTO
Yongin	EverLine	Bombardier	CITYFLO 650	2011	19	30		UTO
Algiers Metro	1	Siemens	Trainguard MT CBTC	2012	9	14	Greenfield	STO
Istanbul Metro	M4	Thales	SelTrac	2012	21.7		Greenfield
Istanbul Metro	M5	Bombardier	CityFLO 650	2017-2018	16.9	21	Greenfield	UTO	Opened in 2 phases the first in 2017 and the second in 2018
Ankara Metro	M1	Ansaldo STS	CBTC	2018	14.6		Brownfield	STO
Ankara Metro	M2	Ansaldo STS	CBTC	2014	16.5		Greenfield	STO
Ankara Metro	M3	Ansaldo STS	CBTC	2014	15.5		Greenfield	STO
Ankara Metro	M4	Ansaldo STS	CBTC	2017	9.2		Greenfield	STO
Mexico City Metro		Alstom	Urbalis	2012	25	30	Greenfield	STO
Mexico City Metro		Siemens	Trainguard MT CBTC	2022-2024	18	39	Brownfield	DTO
New York City Subway	IND Culver Line	Thales & Siemens	Various	2012			Greenfield		A test track was retrofitted in 2012; the line's other tracks will be retrofitted by the early 2020s.
Phoenix Sky Harbor Airport	PHX Sky Train	Bombardier	CITYFLO 650	2012	3	18	Greenfield	UTO
Riyadh		Bombardier	CITYFLO 650	2012	4	12	Greenfield	UTO
São Paulo Commuter Lines	8, 10, 11	Invensys	Sirius	2012	107	136	Brownfield	UTO
Caracas Metro	1	Invensys	Sirius	2013	21	48	Brownfield		-
Málaga Metro	,	Alstom	Urbalis	2013	17	15	Greenfield	ATO
Paris Métro	3, 5	Ansaldo STS / Siemens	Inside RATP's Ouragan project	2010, 2013	26	40	Brownfield	STO
Paris Métro	13	Thales	SelTrac	2010, 2013	23	66	Brownfield	STO
Toronto subway	1	Alstom	Urbalis 400	2017 to 2022	76.78	65	Brownfield Greenfield	STO	CBTC active between Vaughan Metropolitan Centre and Eglinton stations as of October 2021. The entire line is scheduled to be fully upgraded by 2022.
Singapore MRT	Downtown Line	Invensys	Sirius	2013	42	92	Greenfield	UTO	With train attendants who drive trains in the event of a disruption.
Budapest Metro	M2, M4	Siemens	Trainguard MT CBTC	2013 2014	17	41		Line M2: STO Line M4: UTO
Dubai Metro	Al Sufouh LRT	Alstom	Urbalis	2014	10	11	Greenfield	STO
Edmonton LRT	Capital Line, Metro Line	Thales	SelTrac	2014	24 double track	94	Brownfield	DTO
Helsinki Metro	1	Siemens	Trainguard MT CBTC	2014	35	45.5	Greenfield and Brownfield	STO
Hong Kong International Airport	Hong Kong International Airport Automated People Mover	Thales	SelTrac	2014	4	14	Brownfield	UTO
Incheon Subway	2	Thales	SelTrac	2014	29	37	Greenfield	UTO
Jeddah Airport		Bombardier	CITYFLO 650	2014	2	6	Greenfield	UTO
London Underground	Northern line	Thales	SelTrac	2014	58	106	Brownfield	STO
Salvador Metro	4	Thales	SelTrac	2014	33	29	Greenfield	DTO
Massachusetts Bay Transportation Authority	Mattapan Line	Argenia	SafeNet CBTC	2014	6	12	Greenfield	STO
Munich Airport	Munich Airport T2 APM	Bombardier	CITYFLO 650	2014	1	12	Greenfield	UTO
Shinbundang Line	Dx Line	Thales	SelTrac	2014	30.5	12	Greenfield	UTO
Panama Metro	1	Alstom	Urbalis	2014	13.7	17	Greenfield	ATO
São Paulo Metro	15	Bombardier	CITYFLO 650	2014	14	27	Greenfield	UTO
Amsterdam Metro	50, 51, 52, 53, 54	Alstom	Urbalis	2015	62	85	Greenfield and Brownfield	STO
Delhi Metro	Line 7, Line 9	Bombardier	CITYFLO 650	2018 2021 2024	55
São Paulo Metro	5	Bombardier	CITYFLO 650	2015	20	34	Brownfield & Greenfield	UTO
Buenos Aires Underground		Siemens	Trainguard MT CBTC	2016	8	20	?	?
Buenos Aires Underground		Siemens	Trainguard MT CBTC	2016	4.5	18	TBD	TBD
Hong Kong MTR	South Island line	Alstom	Urbalis 400	2016	7	10	Greenfield	UTO
Hyderabad Metro	L1, L2, L3	Thales	SelTrac	2016	72	57	Greenfield	STO
Kochi Metro	L1	Alstom	Urbalis 400	2016	26	25	Greenfield	ATO
New York City Subway	IRT Flushing Line	Thales	SelTrac	2016	17	46	Brownfield and Greenfield	STO
New York City Subway	IND Queens Boulevard Line	Siemens/Thales	Trainguard MT CBTC	2017–2022	21.9	309	Brownfield	ATO	Train conductors will be located aboard the train because other parts of the routes using the Queens Boulevard Line will not be equipped with CBTC.
Kuala Lumpur Metro (LRT)	Line 5, Kelana Jaya Line	Thales	SelTrac	2016	91.5	126	Brownfield	UTO
Metro Santiago		Alstom	Urbalis	2016	20	42	Greenfield and Brownfield	DTO
Walt Disney World	Walt Disney World Monorail System	Thales	SelTrac	2016	22	15	Brownfield	UTO
Delhi Metro	Line-8	Nippon Signal	SPARCS	2017 2021			Greenfield	UTO
Lille Metro	1	Alstom	Urbalis	2017	15	27	Brownfield	UTO
Lucknow Metro	L1	Alstom	Urbalis	2017	23	20	Greenfield	ATO
Metro Santiago		Thales	SelTrac	2017	15.4	15	Greenfield	UTO
Stockholm Metro	Red line	Ansaldo STS	CBTC	2017	41	30	Brownfield	STO->UTO
Singapore MRT	North–South Line	Thales	SelTrac	2017	45.3	198	Brownfield	UTO	With train attendants who drive trains in the event of a disruption. These train attendants are on standby in the train.
Singapore MRT	East–West Line	Thales	SelTrac	2018	57.2	198	Brownfield Greenfield	UTO	With train attendants who drive trains in the event of a disruption. These train attendants are on standby in the train.
Copenhagen S-Train	All lines	Siemens	Trainguard MT CBTC	2021	170	136	Brownfield	STO
Doha Metro	L1	Thales	SelTrac	2018	33	35	Greenfield	ATO
New York City Subway	IND Eighth Avenue Line	Siemens/Thales	Trainguard MT CBTC	2018–2024	9.3		Brownfield	ATO	Train conductors will be located aboard the train because other parts of the routes using the Eighth Avenue Line will not be equipped with CBTC.
O-Train		Thales	SelTrac	2018	12.5	34	Greenfield	STO
Port Authority Trans-Hudson (PATH)	All lines	Siemens	Trainguard MT CBTC	2018	22.2	50	Brownfield	ATO
Rennes ART	B	Siemens	Trainguard MT CBTC	2018	12	19	Greenfield	UTO
Riyadh Metro	L4, L5 and L6	Alstom	Urbalis	2018	64	69	Greenfield	ATO
Sosawonsi Co.	Seohae Line	Siemens	Trainguard MT CBTC	2018	23.3	7	Greenfield	ATO
Buenos Aires Underground		TBD	TBD	2019	11	26	TBD	TBD
Gimpo	Gimpo Goldline	Nippon Signal	SPARCS	2019	23.63	23	Greenfield	UTO
Jakarta MRT	North–south line	Nippon Signal	SPARCS	2019	20.1	16	Greenfield	STO
Panama Metro	2	Alstom	Urbalis	2019	21	21	Greenfield	ATO
Metro Santiago		Thales	SelTrac	2019	21.7	22	Greenfield	UTO
Sydney Metro	Metro North West & Bankstown Line	Alstom	Urbalis 400	2019	37	22	Brownfield	UTO
Singapore MRT	Thomson–East Coast Line	Alstom	Urbalis 400	2020	43	91	Greenfield	UTO
Suvarnabhumi Airport APM	MNTB to SAT-1	Siemens	Trainguard MT CBTC	2020	1	6	Greenfield	UTO
Bucharest Metro	Line M5	Alstom	Urbalis 400	2020	6.9	13		STO	To be fully operational after the delivery of the 13 Alstom Metropolis BM4 trains.
Bay Area Rapid Transit	Red Line, Orange Line, Yellow Line, Green Line, Blue Line	Hitachi Rail STS	CBTC	2030		211.5	Brownfield	STO
Lahore	Orange Line	Alstom-Casco	Urabliss888	2020	27	27	Greenfield	ATO
Hong Kong MTR	East Rail line	Siemens	Trainguard MT CBTC	2021	41.5	37	Brownfield	STO
Lisbon Metro	Blue Line, Yellow Line, Green Line	Siemens	Trainguard MT CBTC	2021-2027	33.7	84	Brownfield	STO
Baselland Transport (BLT)	Line 19 Waldenburgerbahn	Stadler	NOVA Pro CBTC	2022	13.2	10	Greenfield	STO
São Paulo Metro	17	Thales	SelTrac	2022	17.7	24	Greenfield	UTO	Under construction
Melbourne	Cranbourne line, Pakenham line, Sunbury line, Metro Tunnel	Bombardier	CITYFLO 650	2023	115.8	70	Brownfield	STO	CBTC only available between West Footscray and Clayton stations
São Paulo Metro	Line 6	Nippon Signal	SPARCS	2023	15	24	Greenfield	UTO	Under construction
Tokyo	Tokyo Metro Marunouchi Line	Mitsubishi	?	2023	27.4	53	Brownfield	?
Tokyo	Tokyo Metro Hibiya Line	?	?	2023	20.3	42	Brownfield	?
Seoul	Sillim Line	LS ELECTRIC	LTran-CX	2023	7.8	?	?	?
JR West	Wakayama Line	?	?	2023	42.5	?	Brownfield	?
Kuala Lumpur Metro (LRT)	Line 11, Shah Alam Line	Thales	SelTrac	2024	36	25	Brownfield	UTO
Marmaray Lines	Commuter Lines	Invensys	Sirius	?	77	?	Greenfield	STO
Hong Kong MTR	Kwun Tong line, Tsuen Wan line, Island line, Tseung Kwan O line	Alstom-Hitachi Rail	Advanced SelTrac	2025-2029	58.1	128	Brownfield	STO & DTO
New York City Subway	IND Crosstown Line	Hitachi Rail	SelTrac	2029	16	309	Brownfield	STO
Porto Metro		Alstom	Cityflo 250	2024	3.0	18	Greenfield	STO
Ahmedabad	MEGA	Nippon Signal	SPARCS	?	39.259	96 coaches	?	?
Baltimore	Baltimore Metro SubwayLink	Hitachi Rail STS	CBTC	2025	24.8	78	Brownfield	STO	New railcars and signalling system undergoing testing, expected to enter service in mid-2025
Transport for London	Elizabeth line	Siemens	Trainguard MT CBTC	2022	42	70	Brownfield	STO	Paddington to Abbey Wood / Stratford
Jabodebek LRT	Bekasi Line Cibubur Line	PT. INKA	?	2023	44.4	31	Greenfield	DTO
Oslo Metro	All lines	Siemens	Trainguard MT CBTC	2025-2030	85	115	Greenfield Brownfield	STO	Being gradually rolled out throughout the system, first commissioned between Brattlikollen and Lambertseter on Lambertseter Line.
Atlanta MARTA	All lines	Stadler	NOVA Pro CBTC	2024	77	354	Brownfield	STO
Hartsfield–Jackson Atlanta International Airport	The Plane Train	Alstom	?	2024	4.5	63	Brownfield	UTO