IRSE Technical Tour: Dublin
Train protection and level crossing control in Ireland were two of the topics covered in the Institution of Railway Signal Engineers (IRSE) technical weekend held in Dublin in May. Both train protection and level crossings are two of the most important functions provided by the signal engineer. The technical weekend also included a visit to the new National Train Control Centre (NTCC) of Irish Rail (Iarnród Éireann (IÉ)) which is under construction at Heuston, Dublin, as well as a level crossing control centre at Athlone. The event drew attendees from the UK, Eire, Netherlands, France, Spain, Italy, and South Africa.
There were presentations during the weekend to explain the IÉ plan for rail, the history of train protection in Ireland, the IÉ European Train Control System (ETCS), L1 Automatic Train Protection (ATP) programme, and the Indra Rail Traffic Management System (TMS). The Irish Section of the IRSE promotes signalling development, education, and knowledge across the various railway sectors of both Northern Ireland and Eire.
IÉ is building for the future to maximise the role of Ireland’s rail services to meet the growing transport needs of the country. Supported by the National Transport Authority and funded under Project Ireland 2040, a plan to invest in trains, infrastructure, stations, and customer service are part of the National Development Plan 2018-2027. Investment will also support the national Climate Action Plan and includes 790 new train carriages to cater for growing demand, with up to 600 electric or battery electric carriages; investment in track, signalling and level crossings to increase frequency and improve journey times; and new stations and upgraded existing stations including improved accessibility and car park facilities.
Train protection
Train drivers must be provided with clear signal indications so there is no confusion and limited risk of reading the wrong signal. The two main errors a driver can make are failure to control the speed of their train correctly and failure to stop at a signal. It is these functions which a train protection system must address.
Train protection can consist of warning systems and full train protection systems. A warning system will normally be associated with the location at which braking should commence, and a protection system will aim to stop the train at or soon after the end of movement authority.
In Britain, Automatic Warning System (AWS) is a warning system that provides the train driver with an audible warning and visual reminder that they are approaching a caution or stop signal, a reduction in permissible speed, or entering a temporary / emergency speed restriction. Train Protection & Warning System (TPWS), as it names suggests, is the basic train protection system used throughout the British passenger main-line railway network and in Victoria, Australia.
TPWS in Britain was developed from AWS after a decision in 1994 that the installation of a full ATP system was not practicable. Unlike ATP, TPWS will not prevent a Signal Passed at Danger (SPAD) but it does mitigate the consequences of a SPAD, by reducing the speed of a train or stopping it before a conflict point.
In Ireland, a coded track circuit carrier-based ATP and Continuous Automatic Warning System (CAWS) cab signalling system has been used since the early 1980s. This was based on historic North American technology supplied by Union Switch & Signal based in Pittsburgh, Pennsylvania. The system was provided as part of the electrification and driver only operation of the DART (Dublin Area Rapid Transit) network. There was a need to provide rear end train protection via ATP as there would be no guard to protect a failed train. The problem was that, as well as the new DART driver only electric trains, there were also legacy diesel trains from other parts of Ireland running on the same routes as the DART ATP fitted trains.
At the time, these diesel trains could not easily be provided with ATP, as the trains all had different braking curves. Some clever engineering was deployed to provide the diesel trains with a warning system with signal aspects in the cab via the same coded track circuit system. This was called Continuous Automatic Warning System (CAWS).
CAWS repeats the line side colour light signal aspects on an Aspect Display Unit (ADU) inside the driver’s cab. The ADU continuously displays the aspect that was shown by the previous signal until updated about 350 metres before the next signal. The ADU then displays the aspect shown by that signal.
A change of ADU display to a less restrictive signal is called an ‘upgrade’, while a change to a more restrictive signal (single yellow to red) is called a ‘downgrade’. Any change of ADU display is accompanied by an audible indication. A momentary audible ‘warble’ sound indicates an upgrade. A downgrade is accompanied by a continuous audible tone and the illumination of the Acknowledge Switch that must be pressed by the driver within seven seconds to prevent an automatic brake application occurring for one minute.
An ageing system
Since the ATP and CAWS are dependent on track circuits, axle counters cannot be used for train detection, and CAWS does not act in the event of a SPAD if the red aspect has been acknowledged by the driver. It is also a 40-year-old system and the technological and regulatory environment has changed significantly since its introduction. In addition to the difficulties of maintaining the ageing system, the technology did not deliver several features of modern ATP systems, such as automatic train stop, train-regulated line speed, and compliance with speed restrictions.
IÉ looked at options to replace their coded track circuit carrier-based ATP and CAWS. They initially decided against ETCS, as it was still relatively new and IÉ didn’t have a need for high-speed rail like other railways. So, it decided to develop Iarnród Éireann Hybrid System (IÉHS). The concept of IÉHS was that it would be a balise based system (similar to ETCS), providing modern full ATP features and designed to work as an ‘add on’ to the existing ATP and CAWS, with track circuit code being used to provide continuous infill where code was unavailable – approximately 50% of the network. However, during the development of the project, problems were discovered with the old-coded track circuit technology and electromagnetic interference (EMI) − unwanted noise − from things like farmers’ electric fences, rebar (reinforcing bar) in concrete sleepers, and even magnetic ‘puddles’ from rails that had been handled with magnetic grabs.
ETCS had by this time become more mature, with several railways successfully deploying systems, and new trains were on order for Ireland that could be provided with ETCS. GSM-R, which provides the communication to the train rather than coded track circuits, was also now available. So, it was decided to deliver ETCS Level 1 Train Protection System (TPS) to provide train stop and overspeed supervision (permanent and temporary speed restrictions), as well as protection against SPADs and buffer stop collisions. Supplied by Alstom, the first stage of ETCS implementation will be on the Dublin Connolly based lines between Dundalk in the north and Greystones in the south.
Covering a distance of approximately 125km, this initial phase will involve about 400 signals and include the only routes in Ireland currently electrified. This will involve manufacture and installation of about 180 location cases, 1,350 balises, and 50km of cable containment housing some 135km of cables. Ultimately, the rollout will include most of the existing operational network, some 450-route km of multiple track and 1,100 route km of single track, involving more than 1,600 signals and 5,000 balises.
The ETCS trackside subsystem will be overlaid on existing signalling system consisting of 11 SSIs, four centralised relay interlockings, and relay-based auto signals with TPS location cases next to the existing signals.
Indra traffic management system
A contract has been awarded to Indra to develop an advanced rail TMS to control the majority of the IÉ network. Indra, based in Spain, is one of the leading companies in traffic management, with projects in countries including the United States, Australia, the Netherlands, Lithuania, Saudi Arabia, Turkey, Mexico, Colombia, Malaysia, and India.
Indra will design and install an automated integrated control system, which will enable management tasks to be centralised, providing efficiency while improving passenger service, incident resolution procedures and maintenance. The scope of the Indra TMS includes the design, supply, installation, and commissioning of fully integrated and control equipment, as well as its maintenance for 15 years, with the possibility of extending it to 20 years. It also includes training facilities, such as a signalling simulator, as well as providing a backup control centre.
The TMS system is based on the Indra Mova Traffic line of solutions. The new control centre at Heuston will have the capacity to control the majority of signalling systems on the network to manage in the order of 600 passenger trains and 10 freight trains per day operating on the 2,400 km rail network. An automatic router, communications, network management, a control panel and remote monitoring will be part of the TMS. Train circulation will be optimised, reducing potential conflicts and errors by providing operators with a single interface and making information easily accessible to all stakeholders.
Access to the railway for maintenance work and incident control will also improve, enabling fast and efficient resolutions. The system already controls more than 3,000km of high-speed rail in Spain, 500km of the Mecca-Medina high-speed railway, almost 2,000 km of the Turkish high-speed network, and other networks of different characteristics in countries such as Lithuania, Malaysia, Colombia, Morocco and Spain.
Indra says its Mova Traffic rail traffic management solution will incorporate digital big data, artificial intelligence and IoT technology. It will make it possible to “adapt transportation to actual demand, improve the passenger experience, facilitate maintenance, and more intelligent, safe, sustainable, efficient, collaborative and open mobility”. Indra has been working in Ireland for more than 15 years in the transportation market, with projects such as the Dublin Port Tunnel and many of the toll roads around the country.
Control centres
On the Saturday, a visit took place to the impressive new NTCC at Heuston in Dublin, which will replace the existing Central Traffic Control Centre at Connolly station as it is at full capacity and is reaching its end-of-life. The NTCC building is still under construction, but once completed it will be IÉ’s centre for the management and regulation of train movements on the network. In addition, the NTCC will house other co-located control centres, specifically a control room and a regional traffic management control centre for An Garda Síochána, Ireland’s national police and security service.
The NTCC will also provide real-time customer information at stations on the IÉ website and social media platforms. The existing Connolly control centre will be used as a backup centre to the NTCC. The top floor of the new building will be for An Garda Síochána, which will be the first to move into the building at the end of the year.
Level crossings
After visiting a valeting complex to inspect a train, the group travelled by train to see the Athlone Level Crossing Control Centre (AE LCCC).
Around the world, accident statistics demonstrate that level crossings are high risk sites for all railways and they also contribute to many near-miss events. There are many types of technology available to signal and telecoms engineers to provide the right combination of equipment for level crossings to be safe, effective, and affordable. Convenience to the level crossing user is also an important factor in any system selection.
IÉ has created level crossing control centres at Athlone and Mallow which can each remotely control up to 96 crossings via CCTV. The control centres run on Industrial PLC’s that are SIL4 certified. The control centres communicate and control each individual level crossing over the IÉ internal fibre optic network. On the journey to Athlone the train passed through three level crossings which are controlled from Athlone: Meelegans, Ashfield, and Bunnavalley.
The AE LCCC was previously a goods shed and a Guinness store and was established in 2007 with, at first, eight level crossings. Each crossing was upgraded from either a mechanical gated crossing or automatic half barrier to four full barriers. Once this was completed, the crossings were switched to remote working and controlled from Athlone via CCTV and PLCs.
There are six central PLCs in Athlone which communicate over the fibre transmission system to an individual PLC located at each crossing. A central PLC has the capacity to communicate with up to 16 level crossings, thus giving AE LCCC the total capacity of 96 crossings. Currently, AE LCCC controls 85 crossings spanning across four lines: Galway Line – 14 crossings; Mayo Line – 39 crossings; Sligo Line – 14 crossings; and Waterford Line – 18 crossings. The centre is currently staffed by 26 crossing keepers, with a minimum of four working together on any day shift, plus a supervisor.
After returning to Dublin the technical weekend was followed by a two-hour show including an interactive and memorable concert of authentic Irish music performed by impressive local musicians and troupe of Irish dancers. The IRSE and Irish Section are very grateful for the financial support received from RIVVAL, Alstom, and Indra for the event, and ‘benefit in kind’ support from Iarnród Éireann Irish Rail, Transdev, Dublin tram operator Luas, and Purcell Construction.
