Signalling & Train Control System In Dubai Metro

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DUBAI METRO SIGNALLING & TRAINCONTROL SYSTEM

Shiv Mohan, CEng, BTech, MIRSE, PMP, MIET, MIEEE, Serco Dubai Metro

SUMMARY

This paper is a case study of Dubai Metro Signalling & Train Control system. Dubai Metro is the world’s longestfully Automated Driverless Metro System. Dubai Metro has taken the lead role to introduce CommunicationBased Train Control in the Arabian Peninsula. It probes into the reasons why Dubai Metro has gone for CBTCsignalling & train control system. It details the features of Dubai Metro signalling & train control system andenumerates the implementation & operation challenges faced by Dubai Metro, benefits and lessons learnt therefrom. It also gives an overview of the signalling requirements of different upcoming lines & extension of DubaiMetro. The success of Dubai Metro has shown a path to upcoming Metro systems in the Arabian Peninsula likeKuwait Metro, Makkah Metro, Abu Dhabi metro and Doha metro. In this paper we shall also discuss theimportant issues & future challenges like specific environment issues, interoperability in view of the fastchanging transport scenario in the Middle East.

1 INTRODUCTION

An efficient transport system is the key root of economic growth of any country. The rapid worldwide expansionin requirement of an urban transport system in the last few years has led to the planning and development ofmass rapid transit systems in the Middle East. Success of such a system lies in the ability to provide frequent,fast, safe and comfortable journeys to a large number of regular travellers & tourists. The phenomenaladvancements in the fields of electronic & software systems have enabled metro signalling to develop intelligenttrain protection, operation and railway control systems, and signalling plays a major role in their ability toachieve these aims. Dubai Metro has taken care to introduce all the modern trends in Metro rail signalling, andaccordingly has gone ahead with modern Communication Based Train Control signalling system, which is thefirst one of its kind in the Middle East.

2

DUBAI METRO- NEED & FEASIBILITYLike all modern cities of the world, Dubai transportation needs are growing rapidly due to increasing demandgenerated by upward trend of international business relocations, swell in commercial activities, growth oftourism and increasing population. As part of its modernity drive, vision and concerns for the environment, theDubai Government commissioned studies to evaluate the most efficient and cost-effective solution to combattraffic congestion and its pollution by-product; the recommendation of these studies were the creation anddevelopment of a Metro for Dubai City.

As a city grows in size, the number of motor vehicles and consequently the numbers of vehicular trips on roadsystems go up, leading to severe congestion on the roads. This necessitates a pragmatic policy shift todiscourage private modes and encourage public transport, once the level of traffic along any travel corridor inone direction exceeds 20,000 persons per hour. A comprehensive study about growing need of mass transportbrought out the need of a Dubai Metro. A rail based metro has a high carrying capacity and is non–polluting. It

uses about one-fifth energy per passenger-km compared to a road based system. Moreover, it is fast, reliable,safe and comfortable to commuters.

The Metro system planned for Dubai consists of both underground and surface corridors covering a total routeof 74.6 km. It consists of two lines totaling 47 stations, of which 10 stations are underground, 36 elevated & 1graded station. The Red Line has a capacity of 23,000 people per hour in each direction, and the Green Line isable to shuttle 19,000 people per hour.

In May 2005, Dubai Metro design and build contract was awarded to the Dubai Rail Link (DURL) consortiummade up of companies including Mitsubishi Heavy Industries, Mitsubishi Corporation, Obayashi Corporation,




Kajima Corporation and Yapı Merkezi. Work officially commenced on the construction of the metro on 21 March2006. The Dubai Metro is the flagship Project of the Roads and Transport Authority (RTA)Dubai.

The Red line was opened 9 minutes and 9 seconds past 9 PM on 9 September 2009 (9/9/9 9:9:9) and theGreen line was opened on 9/9/11. The first two lines are shown in Table 1.

Lines Sections Trains Depots Length (Km) No. of Stations

Red Line Rashidiya – Jebel Ali 44 2 52.1 29

Green Line Al Qusais- Creek 17 1 22.5 20

Total 61 3 74.6 47 ( 2 commonstations)

Table 1: Dubai Metro Lines

Dubai Metro is the world's second most affordable metro transportation system after Tehran Metro in Iran.Dubai Metro has generated substantial benefits by:

1. Contributing to the appreciation of the value of lands & commercial properties as much as by 7 to 34%. 2. Generating high economic returns highlighted by its ability of the competitiveness of the Dubai as

regards the attraction of commercial activities as well as the local & international events spanningconferences and sports events.

3. Generating the revenues for Dubai by advertising activities, naming of stations (Corporate branding)and leasing of commercial outlets.

4. Siphoning off commuter trips per day from the roads of Dubai. This will translate into fewer Cars cars& buses on Dubai roads increase in average speed of road traffic, saving of fuel cost, reduction inpollution levels and reduction in road accidents.

5. Improving work productivity by saving total man-per day and reducing commuter stress.6. Changing the lifestyle by encouraging commuters to spend more time reading during their journeys

and increasing people interaction between different communities & nationalities.

Figure 1: Dubai Metro Map




3 REQUIREMENTS OF SIGNALLING SYSTEM OF DUBAI METRO

The green and red lines Automatic Train Control (ATC) system is based on state-of-art, yet proven in use;communications based train control technology, using continuous bidirectional digital communications betweenintelligent trains and a network of distributed trackside computers designed for very high system reliability andavailability.

The primary characteristic requirements of the ATC system include:

1. High resolution train location determination by trainborne equipment.2. Communications of train location information and other train status data to trackside computers over

train to trackside communication link.3. Determination of movement authority limit information for each intelligent train based on train location

information and processed input from the trackside interlocking.4. Communication of these authority limits and other train control data to the appropriate train over the

trackside to trains communication link.5. Determination and enforcement of the safe speed distance profile by the trainborne equipment.6. Central supervisory computers, the Automatic Train Supervision (ATS) system, provide train

scheduling and general operating and control information to provide optimal system throughput, controland flexibility.

7.

The train control system provides short interval, great operational flexibility, safety through continuousover-speed protection, smooth and predictable operation, high reliability and availability, optimizedmaintenance tasks.

8. The ATC system shall make provision for the insertion of new stations within the lines as well asprovision for lines extension.

9. The normal train control system shall be communication-based. Equipment reliability, redundancy, andsystem architecture ensure that the operation of the system continue in the presence of any singlepoint failure.

10. The ATC system shall be designed such that equipment failure rates shall be sufficiently low topreclude the need for manual driving operation, which shall be exceptional in case of failure.

11. Under normal operation, ATC automatic mode shall require no Operation Control Centre (OCC) staffintervention other than supervision and minimum OCC staff intervention when out of normal operation.

12. Any equipment failure or line interruption shall be instantly reported to OCC and lead to minimal

service disruption, as high availability requirements shall be met. In case of significant failure, thesystem shall then fallback to alternative modes of operation under OCC staff full supervision.

13. In normal operations, train will stop at every station. Under degraded mode of operation it shall be,however, possible to modify the standard configuration, skip a station or all the stations (through train).

14. Initialisation of automatic operation after system start up must be possible without manual interventionlocally in each train, nor require OCC operator command to be made for each train.

15. All parts of the ATC system including trackside and on-board computers shall be capable of beingremotely commanded to restart.

16. The ATC system shall provide core functions of Automatic Train Protection(ATP), Automatic TrainOperation (ATO) and Automatic Train Supervision (ATS).

17. The design headway shall be such as to allow an operational ultimate headway of 90 seconds for astation dwell time of 20 seconds.

18. The design life of all ATC equipment in service shall be 20 years.

19.

ATC shall provide automatic station stopping. ATO station stops shall be accurate within:• +/- 0.25 metres of the designated stop location at least 99.90 % of the time .

• +/- 0.5 metre of the designated stop location at least 99.99 % of the time.




3.1 Automatic Train Protection (ATP)

The ATC system shall provide the maximum safe operating flexibility and allow all safe operating running. Thissub-system, which is concerned with fundamental safety of train operation, performs the following functions:

1. The ATP shall detect the presence of trains and any maintenance vehicles. 2. Ensure and maintain safe operation between trains.3.

Detect the speed & determine the maximum safe speed at the train location, for comparison with theactual train speed.

4. Ensure that the train deceleration rate used for braking is reached within specified time of servicebrake application, otherwise application of emergency brake takes place.

5. Detect “roll back” of the train and cause brake application.6. Detect an unexpected loss of train integrity and establish appropriate limits of authority to prevent other

trains from entering in that area.7. Provide Movement of Authority & Train and Platform Screen door safe protection.8. Wayside and On-board Obstacle detection and Protection.9. Provide Securing of routes and Switch Interlocking.

3.2

Automatic Train Operation (ATO)

The ATO function shall provide commands to vehicle subsystems, in particular the propulsion unit, to ensurereliable and comfortable service for passengers as described below:

1. Control Train acceleration, deceleration, and station stop.2. Control the vehicle speed to meet the acceleration and jerk limit requirements, minimize runtimes or

adapt runtimes to OCC regulation needs, avoid unnecessary power/brake transitions, avoid over speedconditions, provide the smoothest practical ride for passengers.

3. Control the station dwell as per service regulation needs.4. Command platform screen doors and train doors to simultaneously close, proceeded by an audio and

visual signal for passenger information.5. Programmed Station Stop.6. Address other sub functions (i.e. Train identification, PSD control, Train departure testing, Train health

monitoring, automatic route initialisation, Route selection etc.)3.3 Automatic Train Supervision (ATS)

This computer-based sub-system overall controls from the Operations Control Centre (OCC) and stations andinclude the following functions:

1. Execution of instructions received from train controller.2. Direct a train or group of trains to skip a station or group of stations.3. Enable the OCC or the station master office to hold a train in a station.4. Train dispatching & adjustment of station dwell time.5. Provision of output to platform indicators and/or other passenger/management information media.6. Commands to station interlocking & computation of train schedules.7. Monitoring of train position and progress.8. Display of train service status to train controller.9.

Logging and compilation of records.10. Interface with other sub systems such as Onboard system.




4

SIGNALLING & TRAIN CONTROL SYSTEM FOR DUBAI METRO

The Signalling & Train Control system for Dubai Metro is a proven product from Thales Railway SignallingSolutions (TRSS) called SelTrac S40 (also called SelTrac IS). It is a fully integrated Automatic Train Control(ATC) system based on the Moving Block concept. SelTrac S40 is being used in various railway lines across theworld ( i.e. DLR, KCRC, Vancouver etc.) Figure 2 shows the configuration of signalling & train control system

4.1

System Management Centre (SMC)

The System Management Centre (SMC) is the overall management facility. It serves as the interface betweenthe system and Central Control Operators (CCO) and provides the required ATS level automatic control andsupervision functions. Its primary function is to provide information to the CCOs on the position and status of alltracked trains and status of the field equipment within the ATC system. Train and guideway control commandsare entered via the CCO workstations. SMC consists of SMC workstations, Schedule regulation subsystem,Timetable compiler, database servers, SMC I/O rack, Availability Module.

4.2 Vehicle Control Centre (VCC)

Safety Critical Operation is the responsibility of VCC. The VCC is the Master control. The VCC enforces a

minimum safe separation between trains. All interlocking functions are performed by the VCC. The VCC is inconstant contact with all trains and all wayside devices. Based on this real time information, the VCC candetermine and send a movement authority to each train and can send commands to position the waysidedevices necessary to achieve the routing request. A VCC consists of a Central computer rack, I/O rack anddata communication rack, VCC CCOT and emergency shutdown buttons. There are in total 10 VCC in Dubaimetro (6 on the Red line and 4 on the Green line).

4.3 Vehicle On-Board Controller (VOBC)

VOBC provides the On-board ATO and ATP functions to the vehicles. The VOBC communicates constantlywith VCC and is primarily responsible for the control of propulsion, brakes and train doors under ATPconstraints. It interprets and supports VCC commands including maximum speed, target point, door control andbraking rate. It performs vital supervisions including over-speed, target point overshoot and door statusdetection to ensure that train is operating within its permitted envelope. Each train has 2 VOBC in front and rearcar with other on-board equipment (1 accelerometer, 2 Tachometer, 2 Receive & 2 Transmit Antenna, 2 dockingloop antenna and 1 proximity sensor for each VOBC).




Figure 2: Seltrac S40 Signalling System Configuration on Red & Green Line

4.4 Station Controller (STC)

The STC provides Automatic switch control and supervision of all switches, monitors and reports intrusionstatus and status of platform emergency stop buttons. The mainline STCs also provides Platform Screen Doors(PSD) control and monitoring. A STC consists of 1 Electronic Rack and relay Rack. There are twoconfigurations of an STC:

i.

Redundant Intersig Configuration for mainline,

ii. A single Intersig Configuration for depots

4.5

Platform Door Interface Unit (PDIU)

The PDIU provide supervision for the PSDs, monitors and reports intrusion status and status of platformemergency stop buttons. At the transition zones between the tunnel and the raised guideway, the PDIU alsomonitors the status of the Wayside Obstacle Detection System (WODS) for intrusion onto the guideway.

4.6 Inductive Loop Communications

The Inductive Loop Communications equipment is located in equipment rooms and at trackside. The InductiveLoop Data Communication system is the means by which the VCC and the VOBC in each train exchange

information. The Inductive Loop Communications consists of Feed in Devices (FID), Remote Loop Boxes andInductive Loop Cable.

4.7 Operations Control Centre (OCC)

The OCC is the nerve centre for train operations and is situated at Rashidiya Depot. It houses relevantcontroller workstations & consoles, visual control panel and the required communication & security facilities.Facilities to cater for interim train operation and also as a backup with full OCC functionality are provided atBOCC of Jebel Ali Depot. The physical locations of various trains are indicated to the controllers of OCC onVCP/workstations which are used for getting an overview of train location in entire Dubai Metro.




4.8 Redundancy

All important subsystems are duplicated to ensure that a normal failure does not cause stoppage of trainservices. These include computers, microprocessors and power supply backups etc.

4.9 ATC Internal & External Interface

ATC logical internal and external interfaces are shown in figure3.

Figure 3: ATC External & Internal Interface

5 CHALLENGES DURING CONSTRUCTION & OPERATION

The challenges faced and fortunately overcome for the Dubai Metro ATC system can be summarized as:

1. The system size was itself a big challenge for construction. The Red Line (52.1km) represents thelongest driverless line in the world. The Red and the Green lines (74.6km) represent the longestdriverless system built in one phase.

2. This was the first metro project in the Arabian Peninsula region. The expertise and technology was not

available in the region for Automatic Train Control.3. The harsh environmental conditions in Dubai such as extreme heat, high humidity, sand etc. This has

imposed strict constraints on the hardware requirements. This was also a big challenge for the staffperforming the installation and testing activities.

4. The large and complex interfaces developed between the ATC system and many other subsystems(such as Trains, Maintenance vehicles, Operation Control System, Platform Screen Doors, MultiService Network, Maintenance Management System, Wayside Obstacle Detection System etc.)

5. The considerable amount of automation required in Dubai system such as the fully automated depot,the fully automated train wash, the full automatic control of stabling shed doors etc.




6. A tight project schedule to meet the 09/09/09 date. This resulted into a compressed time schedule fortesting & commissioning for signaling system.

7. Planning for the proper working & traffic control in the most congested areas.8. Coordination between large multi-national, multi-lingual and multi-cultural workforce.9. Suitable alignment interface with road projects.10. Ridership pattern was difficult to guess and different user’s behaviours due to first time in the region.11. Operator was involved later. To recruit & train wider multinational workforce to work on 09/09/09 was a

big challenge for Operator.12. Operation procedures were paramount in degraded mode (i.e. Train time out )

6

LESSONS LEARNT DURING CONSTRUCTION & OPERATION

The Dubai Metro has met the above challenges by having a unique project management and operationstrategy. The following are the features of that strategy which will work as lessons for future metros in theMiddle East.

1. Dubai Metro engaged a Dubai Rail Link (DURL) consortium of 5 international contractors to assist inplanning & execution of work. Concession with world class operator & Independent Safety Assessor.

2. Time bound review of technical specifications / technologies, to be of world class metro.

3.

Nurturing a unique work culture among multinational workforce.4. Training, competency and motivation of employees.5. Good Public/passenger education/awareness due to first metro in the region.6. Identification & early resolution of critical and important issues by special task forces during

construction & operation.7. Seeking intervention of higher authorities for timely resolution of third party issues.8. Close monitoring at all stages of work.9. Communication & marketing strategy.10. Enthusiastic staff from trainees to experienced professionals with diverse railway backgrounds.11. Treating success of contractors as success of project.12. Contractors and employees advised each other about anything which can affect the time or cost.13. The Dubai Metro ATC system (with all its software and hardware components) went through rigorous

testing following a comprehensive test plan.

14.

Involvement of the operator during the system operation demonstration period. Timely access toinfrastructure for training.

15. Presence of experts from system supplier in OCC during initial launch period of the Red line for fastresolution of fault and learning of operation people.

16. Safe management of the outstanding works and configuration change management during operation.

17. Additional maintenance of golden assets due to harsh environment ( i.e. switch machine due to highdust and sand levels).

18. Track markers have been provided to support manual train driving in exception case, post opening.

19. Optimization of maintenance regime with consultation by system supplier and stakeholders.

20. Maintain focus upon operation & maintenance throughout construction works.

21. Provision for adequate pocket tracks, emergency crossovers & O&M staff facilities.

22. Mock drill and test case on failure scenario, proper and fast recovery procedure.

7 SPECIAL FEATURES OF DUBAI METRO

The Dubai Metro uses the service proven new generation technology for Automatic Train Control. Anumber of features in addition to the constraints mentioned earlier make Dubai system differ from otherautomated systems around the world. Examples of those functions are given below:

1. No secondary detection. 2. VCC auto restart & Platform Door Interface Unit (PDIU) Override.

3. Automatic Depot Operation (3 Automatic depots).




4. Automatic train wash and automatic control of shed doors.5. Distributed VCC Architecture ( first time in SelTrac history).6. “Distance to end of manual route reservation” message in train operator display.

7. Wayside obstacle detection system & train on-board obstacle detection system interface.

8. ATC interface with fire protection system and traction power system.

9. Emergency call box and emergency door lever status to trains via Operation Control System.

10.

Bilingual user interface for the operator (Arabic and English).11. A number of remote functions to facilitate the operator work.

12. ATC simulator with interface to the OCS simulator at BOCC.

13. Automatic train coupling.

8

FUTURE PROSPECT & CHALLENGES FOR DUBAI METRO & METROSIGNALLING IN THE MIDDLE EAST

Currently the trend in railway projects is moving towards the driverless technology. The Dubai Metro has beenoperational since 9/9/9 thus proving very successful and reliable. The Dubai Metro has achieved a more than99 per cent punctuality rate in initial operation period, which is the highest of any driverless metro system in theworld. The system is flexible enough to expand further when the Green Line and the Red Line Extension will be

implemented. In 2020, the system shall run at full capacity using the maximum number of trains at headway of90 seconds.

The Roads and Transport Authority master plan includes 320 km of metro lines up to 2020 to cater for theexpected 3.3 million population of the city including the Yellow, Blue and Purple lines. There are plans for 268km of light rail tracks to act as a feeder system for the Metro. The Al Sufouh Tram project is under constructionand is expected to be completed in 2014. It will run 14.5 km along the Al Sufouh Road from the Dubai Marina tothe Burj Al Arab and the Mall of the Emirates. It is expected to interchange with three stations of the DubaiMetro's Red Line and will also link up with the monorail of the Palm Jumeirah.

Due to unique features of signalling system, operational principles and performance of the Dubai Metro makes ita role model for other Metro system in the Middle East like Makkah Metro, Abu Dhabi Metro, Doha Metro,Kuwait Metro and the UAE main line Etihad Railway.

Some future challenges which are very important for the Dubai Metro and Metro signalling in the Middle Eastare detailed below:

1. Interoperability between different signalling system & different onboard equipment will be a challengeto interconnect different lines in future.

2. Connectivity between Main Line railway network (Etihad railway) & Metro network.3. With the increasing population, performance of signalling system in terms of capacity and in terms of

traffic management will be a challenge.4. Tough environment conditions due to high heat and dust.5. Remote condition monitoring is required for equipment which are exposed to harsh environment.6. Energy saving initiatives & green CBTC. How can Signalling System support?7. Improved robustness against EMI/EMC/Noise issues. How can CBTC support better?8. Extension of asset lifecycle and reductions in asset life-cycle costing.9. The systems are all microprocessor based. Equipment obsolescence is a major challenge with growing

technology.10. Insufficient number of suppliers of Metro Railway signalling systems in the Middle East.11. Transfer of technology and self-dependence in Metro signalling System.12. Education, research and development facilities about modern signalling systems in the Middle East.13. Lack of Metro signalling skilled people and experts.14. To keep staff interested in new technology and their knowledge up to date.



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Signalling & Train Control System In Dubai Metro

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