A ‘Must’ Read for Rail For The Valley – Diesel trams: a new way forward? Part 1


Diesel trams: a new way forward?

By Charles King – Modern Railways March 2007

Light rail technologies have received closer attention in recent times as potential solutions to transport problems as well as providing alternatives to ‘traditional’ railway operation. In light of this, a trip run by ACoRP(Association of Community Rail Partnerships), and organised by Faber Maunsell, took eight delegates from Network Rail, the Department for Transport and Transport Scotland in December last year to Switzerland and Germany. The aim of this was to study developments in light rail and their applicability to the UK.
A major focus of this trip was ‘tram-train’. For many people, this concept is most closely associated with the city of Karlsruhe in south-west Germany, which pioneered the technology in the 1990s. Essentially it involves the ‘joining-up’ of a tram network with heavy rail so that local services sharing paths with conventional trains on the main line can travel over both systems, enabling seamless through journeys. The need to change modes is thereby eliminated: accessibility is improved and end-to-end journey times drop. In Karlsruhe’s case, the city centre, about two km from the main station, was the main attraction, and a through journey from the suburbs with dual-voltage electric trams was made possible.
Factors for success
 Karlsruhe’s success has led to numerous developments and extensions, most recently conversion of the 30-km long Murgtalbahn to tram-train operation, which took only seven years from conception to completion at a cost of Euro75million (£50million). The longest possible journey on the system now takes in tramways in both Karlsruhe and Heilbronn as well as main-line railway over its 150-km route from Achern to Öhringen.But it is perhaps surprising that not more schemes modelled on this apparently thriving example have come to fruition, even in continental Europe. Those that are operational include Saarbrücken in Germany and the Rijn-Gouwe-Lijn through Leiden and Gouda in the Netherlands, with the French city of Mulhouse at the initial stages. An overview of these projects reveals that a certain number of factors typically have to come together for a scheme to work:
  •  a common tram and heavy rail track gauge and a suitable interface point between heavy rail and tramway;
  •  a relatively large but dispersed population, ideally with a strong commuting market – Karlsruhe, for instance, serves 120 communities with a total population of 1.3million people; 
  • favourable urban planning and public transport characteristics – the two must be considered together;
  • existing heavy rail stations some distance from the main centres they seek to serve;
  • an ability to overcome the technological challenges such as providing trams with two sorts of traction equipment, signalling compatibility, and meeting the relevant safety standards;
  • perhaps most importantly, the political will and funding to see the project through.

Kassel TramTrain in the city 

 Latest developments

One city where the balance of factors has been positive, however, is the city of Kassel in central Germany, which is currently developing its own ‘RegioTram’ system, due to open in June this year. A total network of 122km is provided with only 10km of new track, serving an urban population of 220,000 with a further 400,000 in the surrounding area. Although the system is based on the ‘classic’ tram-train principle with dualvoltage trams running on the mainline at 15kV AC and on the city tramway at 600V DC, one very significant innovation is the introduction of diesel trams for operation over non-electrified sections of line. This extends their reach beyond conventional electrified routes to rural single-track branches and diesel freight-only lines. Specifically, these vehicles are diesel hybrids: equipped with a diesel-electric engine, they are also able to work on the city tram network at 600V DC.
Each branch will operate to a regular interval 30-minute frequency, with connecting buses at stations along the route in line with the Taktfahrplan principle of bus and rail integration. Coupled with the enhanced journey opportunities, passenger demand on the network is predicted to grow by up to 50%.


Value for money

The total cost of the whole scheme is Euro 180million (£120million), made up of Euro 100million (£67million) for infrastructure and Euro 80million (£53milion) for new vehicles. 85% of the costs were borne by the Bundesland and federal government, with the remaining 15% contributed by the municipal authorities. Key to the tram-train principle, and to the Kassel plan in particular, is maximum use of existing infrastructure to achieve greatest efficiencies and benefits. Diesel trams help to meet that goal by having the ability to fill in the electrification gaps as ‘go-anywhere’ vehicles, but the decision to choose them came about for three major reasons.



  • Large infrastructure costs were avoided: the loading gauge in Zierenberg tunnel on the non-electrified Wolfhagen route to the west of Kassel did not allow for electrification without substantial rebuilding. This resulted in a capital cost saving of Euro 7.5million (£4.9million).
  •  In addition to the costs of rebuilding the tunnel, the capital spend to electrify the 30-km Wolfhagen route would have been around Euro 2million (£1.3million) per kilometre, not including ongoing operational expenditure, and unjustifiable in this case.
  •  Time and money would be saved in the planning process.

  The above savings on the Wolfhagen route represent upwards of 55% of the total infrastructure costs of the entire project, and demonstrate, how much more expensive a fully electric system would be. Feasibility studies carried out between 2000 and 2003 focusing on whether to opt for electric-only vehicles or a mixed fleet containing dieselhybrid versions as well, favoured the latter and resulted in the authority to proceed. As an additional benefit, a short unelectrified freight-only chord at Kaufungen on the otherwise electrified Hessisch Lichtenau route could be brought into use to save eight minutes on the normal end-to-end journey time without any significant infrastructure work – an easy ‘quick win’.


Kassel TramTrain on the MainLine


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One Response to “A ‘Must’ Read for Rail For The Valley – Diesel trams: a new way forward? Part 1”

  1. zweisystem Says:

    Just a reminder that this is a three part series.

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