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IMechE Technical Tour 2024

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Malcolm Dobell & David Shirres

Each year a group of young engineers (and some of more mature years…) takes a study tour of railways, usually in Europe, and 2024 saw an eight-day, four-country tour taking in Austria, Slovakia, Hungary, and Croatia. Ably led by Professor Felix Schmid, Railway Division Chair Andrew Skinner, and Railway Division North West Centre Chair Lyndon Platt, a group of almost 40 engineers including some long-suffering wives toured rolling stock, infrastructure installations, projects, and other sites of interest.

The tour started with two full days in Vienna where the group visited a Wiener Linien depot to see a new metro train, the Semmering base tunnel works, and a huge gravity marshalling yard.

Wiener Linien

The Vienna metro system comprises five lines with a sixth soon to be opened. Lines U1 – U4 operate under driver supervised automatic train operation (Grade of Automation 2 – GOA2) currently with two classes of metro train – the original ‘Silver Arrows’ and the early 2000s’ V-trains. They use the LZB signalling system communicating though ‘wiggly wires’ in the track.

Line U6 was converted from a former main line and, because of low height platforms, is operated by light rail/tram style trains. U5, which is due to open in 2027, will be a driverless – GOA4 – system. It will use Siemens Trainguard MT signalling communicating by Wi-Fi and new X-Wagen trains (see below), some of which will be deployed on other lines.

The Erdberg depot in the east of Vienna serves lines U2 and U3. It is directly on U3 and has a 2.1km connecting line to U2. The depot is approximately 2km long and provides for stabling and maintenance.

Siemens X-Wagen is a six-car train in formation T-M-M-M-M-T designed for GOA4 operation where every platform is equipped with screen doors. Although the gap between the bodyside and PSDs is generally filled by the train’s plug doors, on some legacy lines the curvature is such that laser intruder detection is required for the worst gaps. Doors have obstacle detection and sensitive door edges and every doorway has an extending platform-train gap filler.

Siemens X-Wagen Train. Credit: Siemens

Despite GOA4 operation, the train retains drivers cabs at the outer ends which are to be eliminated later. The trains are manufactured in Siemens’ Vienna factory. Both the factory and Erdberg are connected to the OBB network, but because Wiener Linien uses a much thinner flange than OBB, the trains have to be transported on carrier wagons. To meet tough fire regulations, moulded wooden seats are provided. There are 60 fewer seats than before which delivers 100 more passenger spaces; seats are arranged to encourage passengers to move away from the doors. The trains weigh 159 tonnes tare and 267 tonnes crush (6.6 passengers/m2). Train data, passenger information, and live internal CCTV can be communicated to/from the control room via a Wi-Fi system (separate from the signalling Wi-Fi).

Each of the four motor cars have four air-cooled induction motors controlled by variable frequency-variable voltage inverters from the underside contact 750V DC conductor rails. The trains can brake to a stand using the dynamic brake down to a speed at which brake effort starts to fade. At this point, reverse power is applied to stop the train, power is then quickly removed, and the holding brake applied. The friction brake supplements the dynamic brake at high speed or high load, as a holding brake and as an emergency brake.

These trains are the first to have an innovative, air-free, electrically controlled brake system on each axle. This is a Siemens/Liebherr electro-hydraulic which has the hydraulic pump, accumulator, and actuator contained in calliper housing. The accumulator provides reserve brake force for use in emergency if power fails and the parking brake is locked on with a mechanical latch. Other features ‘underneath’ include resilient wheels, obstacle detection, and derailment detection. Forty-four trains have been ordered and some have been delivered, costing approximately €11 million each.

Following this visit, the group travelled over the Semmering pass on extremely comfortable ÖBB Railjet trains to visit the Semmering Base Tunnel works which is featured elsewhere in this issue.

Gravity shunting

In Europe there is still a big market for wagonload rail freight. This often requires individual wagons to be switched to different trains to reach their final destination. Vienna’s Central Marshalling Yard, in Kledering on the Eastern outskirts of the city, is huge and deals with around 90 trains a day. To do so it has three areas, each accommodating trains over 700 metres long. These are the 14-track incoming area, a 48-track marshalling area, and an outbound area. In total, the yard is 8.2km long.

This gravity yard operates as follows:

Incoming yard. Arriving trains have their wheel spacing, weight, and diameter measured by sensors to calculate speed for subsequent activities. The locomotive is replaced by a shunter at the back of the train. Staff release the brakes and exhaust air systems so that the brakes cannot apply and also loosen the couplings of wagons that need to be marshalled into other trains.

Gravity shunting. After the incoming area is a point and crossing fan set, leading to a single track on a rising gradient to a hump which then falls though a much larger fan into the 48-track marshalling yard. When the radio-controlled shunter pushes the train up the gradient, staff uncouple the wagons as required.

Marshalling. As uncoupled wagons move over the hump, gravity kicks in and they accelerate away from the rest of the train. A computerised control system sets the points for the correct track, detecting when wagons have passed so the points can be reset as the next wagons might be close behind.

Klederig Marshalling Yard. Credit: Louise Shaw

Speed is controlled both by the shunter speed and the Dowty track retarders in which hydraulic dampers are depressed by wheel flanges running over them. Kledering has 38,000 such retarders and 2,000 spares. The clattering noise of wagons running over them was nostalgic for the older engineers! Once trains are complete, a shunting loco gathers all the wagons for staff to couple prior to the train being moved to an outbound track

Outbound. Here the brake pipes are reconnected, and the train is brake tested using a shore compressed air supply. Once the main line loco is attached, the only test required is ensuring that the locomotive controls the first wagon’s brakes. The site, built between 1982 and 1985 can handle up to 6,000 wagons a day but more typically handles about 3,500.

Siemens ETCS testing

The tour travelled by train from Vienna via Bratislava to Žilina in Slovakia. There it visited Siemens’ train borne ETCS test facility. The group received an introduction to ETCS and how this facility validates trainborne ETCS designs in accordance with EN50129. It was also updated on the progress of fitting ETCS in Slovakia where Level 1 has been deployed as part of the Bratislava–Košice mainline modernisation program, currently in use between Bratislava and Žilina. 

ETCS is nominally a standard product but in order to interface with existing traction and rolling stock, as well as with a country’s legacy signalling systems, each installation type requires some bespoke software elements that need to be proved as an ETCS sub-system before being fitted to a train. The hardware is connected to computers which provide simulated signals allowing the ETCS to think it is fitted to a train so test scripts can be run. Once these tests are completed, the systems might be tested at a test track (e.g., Velim or Wildenrath) prior to commissioning on the operators’ railways.

Numerous on-board systems have been assessed including Siemens’ successful Vectron locomotive for operation in Finland, Sweden, Denmark, Germany Switzerland, Croatia, and Czechia as well as Siemens Velaro EMUs for Turkey, Stadler KISS EMUs, and classes 700 and 717 EMUs in the UK. The team have also dealt with numerous retrofit projects, which currently includes the equipment that will be retrofitted to UK Siemens Class 185 DMUs for the TransPennine Route Upgrade.

ŽOS Vrútky

A coach trip took the group from Žilina to ŽOS Vrútky which was founded in 1874 by the Czech Republic to manufacture and overhaul steam locomotives, wagons, and coaches, gradually adapting to changing technology and customer base. It was privatised in 1994 and now largely concentrates on electric locomotives and coaches, occasionally collaborating with other suppliers such as Stadler.
The facility is an excellent example of an organisation adapting to meet customer requirements. The group saw coach overhauls, locomotives undergoing collision repair, and a huge variety of electric locomotive equipment under repair. This included some large, nose suspended, axle hung DC motors with a pinion at each end to drive two gearwheels on the axle giving rise to speculation about controlling the meshing and backlash on the two geartrains. Many of the group had never seen an AC locomotive’s transformer removed from a loco, let alone a disassembled transformer.

It was also fascinating to see modern wheelsets with wheel cheek brake discs alongside huge spoked wheel centres designed for the older locomotives overhauled here. Many of the younger group members had never seen activities such as rewinding DC motor armatures.

Poprad

The group then travelled to Poprad via the 4.8km metre-gauge High Tatras Cog railway which climbs 444 metres to the ski resort of Štrbské Pleso with a maximum gradient of 1 in 8. En route the group observed along the way that some of the platforms at Slovak stations are very narrow.

The next day the tour visited Tatravagónka’s Poprad wagon factory which produces around two thirds of the company’s total production which, last year was 4,541 wagons and 12,000 bogies, twice that of 2014. The company’s freight wagon production is 30% of the European market.

Visiting the Tatravagonka plant at Poprad. Credit: Tatravagonka.

The company produces a wide variety of freight wagons, almost all of which are to their own designs. These include intermodal wagons, ‘basket’ wagons for HGV trailers, frameless tank wagons, heavy load wagons with six-wheel bogies and discharging hopper wagons. The demand for grain hopper wagons has increased due to the need to transport Ukraine’s grain through Europe due to limited seaborne exports.

All wagons are designed to be able to incorporate digital automatic couplers (DAC) should these be required. The tour was advised that a basic DAC would cost €20,000 whilst the fitment of associated smart systems could cost up to €50,000 per wagon.

The Poprad plant has nine specialised production lines for different types of wagons. The modern technologies used on these production lines included plasma and flame cutting and many robotic welding jigs. Nevertheless, the plant employs 750 welders and has its own welding school.

The bogie surface treatment plant was particularly impressive. After grit blasting, bogie frames are automatically placed in tanks for cathodic dip coating, then transferred to an oven where the coating is cured at 200°C for three hours. As a result, bogies only need to be painted for cosmetic reasons. If the customer requires it, bogies are painted using a robotic painting rig.
From Poprad the group had a five hour train journey to Budapest.

Metro again

The Hungarian capital presented an opportunity to sample the city’s newest metro lines. Construction of the newest metro, M4, started in the early 2000s with the first 10-station section opening in 2014. Unlike the other three lines, M4 is a fully automated, driverless GOA4. The line is 7.2km long, has 10 stations, and runs from the south west of the city to an interchange in the city centre with the principal main line station (which sports a statue of George Stephenson). It runs a 170 second headway with 12, four-car trains in service at peak times.

Class 6112 EMU. Credit: Andrew Skinner

The group learnt that automation enabled higher frequency, leading to more capacity, safer operation, and optimised energy consumption. Although GOA4 operation eliminated train drivers, it increased the number of off-train staff, but overall allowed a much more flexible operation. If necessary, an extra train could be introduced into service without having to consider driver availability. As well as an appropriate signalling system, the key factors Budapest decided they needed for GOA4 were:

  • Automatic, driverless vehicles.
  • Safety of train service including Communication Based Train Control (CBTC), platform protection equipment (see later) together with Automatic Train Supervision (ATS) managing headways.
  • Passenger supervision including CCTV in stations and trains visible in the control room, emergency calls from stations & trains, and public address equipment in stations & trains.
  • Power supply supervision.
  • Mechanical equipment supervision.
  • Fire-protection for tunnels, stations, and trains leading to complex alert handling.

The CBTC system is Siemens’ Trainguard MT similar to that seen in Vienna. Our host explained the principles of moving block signalling and safe braking models. Unlike Vienna, there are no platform screen doors. Instead, a system developed for Nürnberg’s line U3 is used. This has an intruder detection system with emitters on the station wall sending an invisible beam to receivers under the platform. If this beam is breached, trains are stopped and third rail power (underside contact 750V DC) is turned off. Although this system has some false positives, it was much cheaper than platform screen doors. There is also an illuminated strip along each platform discouraging passengers from going too close to the platform edge.

As the group saw, critical to GOA4 operations is an integrated control room with an overall controller together with controllers supervising signalling, power, stations, and technical issues together with multi-skilled people around the line able to intervene quickly in an emergency. The tour also visited the train depot to look underneath one of the 15 Alstom four-car all axles motored metro trains which was undergoing its 10-year maintenance activity.

The morning after the Metro visit saw the group at the Hungarian Railway Museum before taking a 6.5-hour train ride to Croatia’s capital Zagreb for the final visits to two railway manufacturing plants there.

Končar

Established in 1970, Končar produced 349 electric locomotives and refurbished a further 405 for various countries in Eastern Europe up to 2005. From then the company changed its focus to the production of trams and multiple units of which it has produced 156 trams, 45 EMUs, and 12 DMUs. Initially, a joint venture with Gredelj produced 70 model 2200 trams for Zagreb. These are low-floor articulated trams with five cars, two of which are supported between the three cars with single bogies. Končar is responsible for the maintenance of these trams which requires a visit to their plant every three months.

Prototype BMU under construction. Credit: Jonathan Prince

In an emergency, these trams can move a short distance powered by their auxiliary batteries using an in-house developed DC-DC converter that enables the 24V auxiliary batteries to power the tram.

Končar’s 160km/h class 6112 25kV AC EMUs are low-floor four-car articulated units with five bogies. These EMUs are the basis for the company’s low floor Class 7023 DMUs which are three car units with four bogies. Unusually, these DMUs have two roof-mounted diesel generator sets for which there is a roof-mounted feeder fuel tank fed from the main fuel tank on the underframe.

The company’s latest project involves prototype battery electric units (BEMU) and battery units (BMU). The BEMU is a three-car unit based on the class 6112 with 4 x 300kW traction motors. The BMU is a two-car unit with a range of up to 100km. It is charged from a 1 MW charging station which has plug-in charging to avoid any encroachment of loading gauge.

Having seen these battery units under construction and tram heavy maintenance, the group were impressed by what had been achieved by Končar’s 500 employees which include 40 in its technical department.

Grendelj

Grendelj was founded in 1894 as the main workshop for Hungarian Railways’ steam locomotives. Today this vast plant has 80,000 m3 of covered space with all the required facilities for rolling stock production. The tour saw a wide range of activities including wagon production, the wheel shop, coach overhaul, shunting locomotive production. The plant’s production includes around 800 wagons per year and 16 bogies per day for which some wheels have to be bought in as the wheel shop’s capacity is 24 wheels per day.

Though the company recently had severe financial difficulties, it was able to continue to manufacture rail vehicles and return to profitability. In 2021, it became part of the Tatravagónka group. It was noticeable that the plant did not have the same level of automation as there was at Poprad visited earlier in the tour. The group was advised that there was an investment plan for new facilities which is one of the benefits of being part of a larger group.

Shared learning

The tour travelled through four countries, covered 2,000km by train, tram, and bus. It had seen a wide range of activities, some of which were at a large scale such as the Semmering base tunnel works, wagon production at Poprad and the metro/tram networks of Vienna, Budapest, and Zagreb.

Aerial view of the Grendelj plant. Image credit: Grendelj.

After eight full days, the closing dinner, sponsored by Angel Trains, was an opportunity to reflect on what had been learnt. In a speech at this dinner the youngest engineer, Jonathan Prince, quite nicely summed this up. He noted that he initially thought that the itinerary looked vaguely interesting, yet on the tour he was “blown away” each day and often found the following day’s visit to be more impressive than the last. He was also glad to have had the opportunity to see working practices outside the UK. Yet he felt that the connections and conversations between young and experienced engineers were the most important aspect of the tour as this provided real professional development.

Thus, the IMechE and the companies who sponsored this tour, and participation of young engineers do the rail industry a great service. The tour’s sponsors were Eversholt Rail, Angel Trains, and the Manchester Railway Consultancy.

Image credit: Andrew Skinner

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