SJ Class X2000 Modernisation progress

After many years of various problems, delays and postponements, the modernisation of the Class X2 tilting EMUs, which started nine years ago, is now entering its final phase in order to keep them competitive with new entrants in the Swedish passenger rail market by increasing passenger comfort, but also by improving operational reliability and efficiency. 

These trains are better known by the trade name X2000 or SJ2000, but they are also referred to as the Class X2, which coincides with the designation of the power cars. The "new" trainsets, in Swedish "Nya X2000", are redesignated to the Class X2U (Upgrade). The modernisation, first announced in 2013, is intended to extend their service life to 2035.

The Class X2 was produced between 1989 and 1998 by Kalmar Verkstad (before being part of Adtranz), ASEA (which was one of ABB's predecessors), ABB Traction and Adtranz, and started operation on 4 September 1990 on the Stockholm -  Göteborg line, with subsequent expansion to other lines. Its maximum operating speed is 200 km/h, and the highest design speed is 210 km/h. SJ received a total of 43 units.

In addition to these, however, one more was produced, which was then exported to China by ABB in connection with the export of this technology. This unit was bought by SJ in 2014 since more intermediate cars were needed for the planned modernisation and standardisation of train configuration.

Each X2 usually consists of one powered end car (locomotive) without tilting and one driving trailer of second class and five intermediate cars (two of first class, two of second class and a bistro car), all of which are non-powered and have bodyshell tilting.

Division Of Activities 

On 16 January 2014, SJ awarded a contract worth 147 million EUR to ABB for the technical modernisation of 36 seven-car Class X2 units. This contract, or rather this part of the project, was named "X2 Technical Upgrade". On 19 March 2015, Stadler then announced that it had concluded a cooperation agreement with ABB on this project by subcontracting certain components and ensuring their installation.

Stadler has thus become the main subcontractor in this project, responsible for the installation of the new low-voltage cabling (which is of the same type as in the FLIRTs and KISSes) and for the installation of the control system (manufactured by the Swiss company Selectron, which has been part of the Knorr-Bremse group since January 2015). Another participant in the project was the Swiss Südostbahn (SOB) in its pilot phase. The latter provided ABB with premises at the Samstagern depot for work on the pilot part of the train, as well as its expertise in operating vehicles with ABB traction equipment.

SJ's second major contract, originally titled "X2 Interior Upgrade" and subsequently renamed "X2 Comfort", involves the refurbishment of the interior of the trains. SJ awarded this contract worth over 1 billion SEK on 4 April 2016 to Swedtrac, based in Tillberga, north of Västerås and approximately 100 km from Stockholm; Swedtrac was at that time (since 2013) part of the Knorr-Bremse group, more precisely a subsidiary of Knorr-Bremse Nordic Rail Services.

PROSE AB, Västerås (a subsidiary of the Swiss PROSE) was also involved in this part of the contract, signing a contract with Swedtrac on 18 April 2016, for which PROSE provided consultancy services during the tender process. PROSE AB was thus in charge of managing the technical aspects of the project, provided services in connection with the technical documentation and arranged for the procurement of the elements for the interior upgrade, with the exception of the seats, which were procured separately by SJ.

The contract for the modernisation of the entrance doors and the air conditioning was awarded to Faiveley (since December 2016 part of Wabtec). The interior doors are modernised by Pintsch Bamag, and the interior lighting by the Swiss company RailTronic. On the SJ side, a dedicated team of 75 people is involved in the process.

Scope Of X2U Modernisation

The upgrade will cover a total of 228 intermediate cars and driving trailers as the 42 power cars. The difference between the number of 36 upgraded sets and the number of cars is the inclusion of spare cars (SJ deployed 43 X2000s with a variable number of 4 to 7 non-powered cars). The modernisation includes the installation of new electrical equipment, control and diagnostic systems, new driver's cab equipment, etc., and of course a complete refurbishment of the interior.

A crucial element from a technical and operational point of view is the addition of traction equipment for 25 kV 50 Hz, which will allow SJ to use all X2U trains on services to Denmark. This has so far only been possible with the 12 X2 units, whose traction equipment were modified for operation on both voltages in 2000 - 2001, and subsequently the trains were rebranded X2K. The old traction converters equipped with GTO thyristors are therefore replaced by new BORDLINE CC1500 converters from ABB for both 25 kV 50 Hz and 15 kV 16.7 Hz.

With the new traction equipment, the reliability and availability of the X2U units is expected to increase, while reducing power consumption by 5 - 10%. This will be achieved through lower losses in the main transformer, filter and auxiliaries as well as more efficient use of the regenerative electrodynamic brake. A supporting effect will be a driver assistance system for economical (eco-friendly) train control. As the new traction equipment is lighter than the original one, ballast has been added to the power car to maintain its weight of 74 t (18.5 t per axle) to ensure the same adhesion characteristics.

The performance parameters of the new converters would allow traction motors of up to 2,000 kW to be used. However, it was decided to retain the original 815 kW asynchronous traction motors as their condition was considered satisfactory by both SJ and ABB. Given the use of the existing traction motors and axleboxes (and wheelsets), the existing continuous power of 3,260 kW and maximum power of 4,000 kW have been retained, as well as the maximum operating speed of 200 km/h and acceleration of 0,4 m/s2, although this is relatively low in today's terms.

The tilting system has also been retained in the mechanical part and only the new hardware of the control system developed by Stadler and Selectron has been introduced. To make train maintenance more efficient, a remote data transmission system to the depot has been introduced; all X2 units are maintained at the Hagalund (Stockholm) and Olskroken (Göteborg) depots.

Of course, the X2U project also focuses on the interior, including the introduction of improved 5G-based Wi-Fi, new passenger information system, etc. After the upgrade, the units will have 15 % more seats than before: the number of seats will increase from 332 (29 of which in the bistro car) to 360. This is achieved by:
- by converting one of the two first-class cars into a second-class car, 
- by reconfiguring the bistro car and changing the catering concept, with a separate mini-kitchen in first class, 
- new seats (produced by TAPS, Łódź) with a thinner shell, which has made it possible to shorten the spacing between the seats. The original seat pitches in the X2s were 1,000 mm in second class and 1,050 mm in first class. The new pitches are 960 mm in the second class and 980 mm in the first class.

The current X2000 modernisation is also connected with a change of the exterior colours, so after the original blue-white-grey paint from the factory and the later introduced all-grey solution, these trains now carry a third variant of the paint, this time in a combination of two shades of grey.

Project Progress

As a first step, the X2 pilot unit was upgraded and its three cars - the X2 2005 power car, the UB2X 2509 driving trailer and the UA2 2818 first class intermediate car - were transported to Switzerland when they left Sweden on 10 December 2014. The power car was transported to Switzerland because it was the subject of the largest amount of work for the renewal of the traction equipment, and ABB has its own competence centre for traction converters at Turgi (near Zürich) and for transformers in Genève.

On the other hand, the remaining four cars, UA2 2820, UB2 2844, URB2 2614 and UB2 2851, remained in Sweden and headed to Tillberga's workshops. Here they were first used to check the condition of the cars and the scope of work, and to prepare the production area, design workflows and secure components. Although the first modernised train was due to be ready for testing at the end of 2015, the three cars from Switzerland did not return to Sweden until February 2017.

It was originally anticipated that the first refurbished X2U would enter service in the autumn of 2018 and that batch refurbishments of X2 units would begin in June 2018. However, ABB soon discovered that the original production documentation did not quite match the actual state of the cars and that upgrading the quarter-century-old trains required an understanding of 1990s technologies and how they could be linked to systems used in the second decade of the new millennium. In addition, other new requirements and issues began to emerge to be addressed in the design phase, so that a completion date of 2019 and then 2020 was then given. However, even this could not be met.

In December 2017, ABB announced its intention to leave the complete train retrofit business. The X2U contract thus continued to run for some time according to the original division of activities. A major change then occurred on 18 January 2018, when Stadler announced that it would take over Swedtrac Tillberg's workshops from Knorr-Bremse during the first quarter of 2018 and incorporate them into Stadler Rail Service (SRS). Tillberga's workshops have been designated for batch upgrades, where Stadler has created around 60 new workplaces as part of the X2U project to remove some components from the trains being retrofitted and install new components, including a new passenger information system, and to carry out tests.

As of March 2018, the first Verification Train VT1 (X2005), a complete seven-car unit including three X2U pilot cars refurbished in Switzerland, was completed. This unit was used in early December 2017 for night test operation in Sweden on lines with other traffic excluded, at speeds of up to 200 km/h. In early March 2018, the X2 Technical Upgrade project work was completed at Tillberga on the VT2 (X2024), after which it was handed over for interior work as part of the X2 Comfort Upgrade contract. Subsequently this unit was also available for testing.

The VT3 (X2020) was first assembled into a short set consisting of only the power car and driving trailer in early March 2018 after modernisation, and was subjected to trials which saw it arrive in Denmark in August 2021 together with X2024. Following of succesful testing, an approval for Sweden was awarded on 15 May 2021. Then on 29 September 2021 an approval for multiple operation was granted. Three weeks later corresponding approvals were awarded for Denmark.

Regular Service

Finally, it was not until 16 November 2021 that regular service started, when the service 402 to Stockholm departed from Göteborg at 05.44, consisting of the X2008 unit, which had made the journey from Stockholm with invited guests the day before. From that date onwards, one X2U operated the weekday services 402 Göteborg - Stockholm (departing at 05.44 h) and 407 Stockholm (departing at 17.07 h) - Göteborg with a journey time of just under three hours. A second upgraded unit was deployed on the same line in March 2022. In early June 2022, SJ announced that a third upgraded train was returned to service, followed by a fourth one in July. This allowed the X2Us to also start operating on the Stockholm - Malmö route.

In connection with the start of the batch upgrades, a new contract was signed on 10 June 2022, in which all three parties agreed that the SJ contract would be transferred from ABB to Stadler. As a result, ABB will continue to participate in the work, but now only as a subcontractor to Stadler. By February 2023, six X2Us were complete and five passenger service. The current deadline for completing the upgrades of the entire 36-strong X2000 fleet is in December 2026.

Furthermore, Stadler signed the contract in October 2020 with Hitachi Rail to install on-board ETCS on the X2U fleet, the installation running in parallel with the modernisation. After homologation of ETCS operation in Norway, the first completely modernised X2U with ETCS OBUs is expected to be approved in spring 2023.