LRTA logoLight Rail Transit Association
Light Rail for better public transport

This Discussion Document is published by the LRTA Development Forum to stimulate discussion and does not necessarily represent the views of the LRTA



Transport planners have for years wrestled with the problem of improving the parameters of suburban railway track such so that shared use with LRVs becomes possible. Although the rewards for commuters, shoppers and tourists are substantial, actual progress has been surprisingly slow. The common factor of a unified gauge should have spurred on politicians and operators alike to overcome the few outstanding minor problems, made all the more spurious following the major technical breakthrough made by Karlsruhe. The potential benefits in congested cities are very significant, and an encouraging number of tram-train schemes are already in the pipeline.


Transit planners in some German cities have confounded the well established technical rules separating AC catenary operation from DC light rail, barriers that many thought would continue to frustrate rail integration. In many ways, this is a defiance of logical engineering practice that could be laid at the door of that well known expression, necessity is the mother of invention.

Rail passengers coming into Karlsruhe had for many years suffered a gap of some length to reach the CBD, a remoteness compounded by an interurban tramway terminal equally as remote. Although a good local tram service has acted as a feeder to the CBD, it could hardly in itself be regarded as an attractive arrangement. Several places in Britain have in the past been faced with a similar situation but the simple solution often adopted here was to convert to a through bus ride.


The danger of doing something similar in Karlsruhe would be at the risk of a passenger revolt, either going elsewhere or taking to the car. An early move was to extend Albtalbahn interurban services through a pedestrianised CBD and then onto a lightly used freight railway line on the far side. Although tramway voltage was used throughout, this particular move could only succeed once the wheel profiles had been adjusted.

The next move was a concerted effort to solve the power supply problem, with one pantograph being able to cope with both high voltage AC and low voltage DC. Once solved, the way was clear for an LRV to approach Karlsruhe on railway track and then at a convenient point deviate onto the local tramway tracks. Such a move served both the CBD as well as the Hauptbahnhof, an arrangement that was immediately successful. When a passenger check was made it revealed an increase in ridership of 600% (1). This passenger boost encouraged extensions to outlying towns, with Heilbronn’s CBD now connected by tram-train to Karlsruhe, 750V DC at each end and high voltage AC in between (2). During this same period, when many places were looking at ways to trim their high railway costs, NSW (Australia) came up with the idea of partially copying the Karlsruhe practice by replacing heavy rail rolling stock on a branch line with tramway type vehicles. Branded as Parklink, this permitted a refurbished corridor tram from Sydney's former tram system to operate over a short branch to the Royal National Park. This tram-train service was arranged in conjunction with the Sydney Tramway Museum at Loftus (3).


31 years after Saarbrücken had abandoned its historic tram network, a new tram system was opened that made use of the dual voltage concept developed by Karlsruhe. Saarbrücken closely followed Karlsruhe’s example by permitting passengers to travel into the heart of the CBD without a need to change vehicles. The concept of a direct light rail service from towns and villages up to 30km distant was expected to persuade up to 20% of car users to switch to public transport (4). This modest prediction was easily surpassed during the first year of operation, when patronage reached 26 000 per day with about 50% being new to public transport (5). Built with an international flavour, its southern terminal is at Sarreguemines in France, 19km from Saarbrücken, probably a useful factor in spreading the tram-train concept to other parts of France.


The financial return from a number of operating franchises on some of the Regional stopping services in The Netherlands was considered as being far too low and therefore not included by The Netherlands Railways (NS) in their bidding process (6). At this point, the tram-train dual-voltage concept became a contender because not only would operating costs be reduced but patronage would be boosted. This new thinking was put to the test, and after almost ten years of political haggling tram-train trials are being conducted on the Rijn-Gouwe line (7). Six Bombardier-built, partly low-floor, three-section articulated trams, have been borrowed from Stockholm for these experiments. A new chip in their control chopper will make them suitable for 1500V DC operation. For passenger convenience, 300mm high wooden platforms have been added at the three existing NS intermediate stations. If future plans become reality, a two-voltage tram-train, (750/1500V) will eventually run from Gouda, through the streets of Leiden, formerly part of the NZH route of the Blue trams, and possibly later on to the beach resorts of Katwijk and Nordwijk.


STRASBOURGA tramway success story with British- built trams, Strasbourg is now planning some long extensions using the tram­-train principle (8).
MONTPELIERLine 2 will share 2.5km of track with SNCF (9).
MULHOUSEThe proposed tramway will include some tram-train rolling stock (10).
BREMENA very progressive tram system, and planning a regional stadtbahn operated by a fleet of dual-voltage tram-trains (11).
BRAUNSCHWEIG (BRUNSWICK)A narrow-gauge tram system, being altered to mixed-gauge (1100/1435mm) to permit tram-trains to operate over electrified and non-electrified railway tracks. A feasibility study has found that this tram-train network would be more cost-effective than local services being simply transferred to regional control (12).
KASSELAs early as 1995 a light rail service was opened to Baunatal, which required a 2km extension of the tram network to link up with a 4km section of freight railway line. The first series of low-floor trams was fitted with wheel profiles suitable for this heavy rail route. The new 15-minute tram service has doubled patronage in the 7 years since the line opened. A second tram-train project was the re-opening to passengers of the 22km Lossetalbahn (closed to passengers in 1986). Because the freight service had continued, a new infrastructure investment made it possible to accept the 2.3m-wide trams on the larger loading gauge. Patronage has increased 65% since its re-opening in 2001 (13).
ALACANTThe Spanish regional railway operator FGV is to operate a tram-train service in the resort on metre-gauge reserved track electrified at 750V DC. The vehicles will run at 70km/hr in tram mode and at 100km/hr on railway sections (14).


The tram-train problem in Britain appears to fall between two entrenched positions each very far apart, longer trains versus more frequent services (15).


  1. Light Rail and Modern Tramway - October 1996.
  2. Railway Gazette International - September 2001.
  3. Rail Scene Australia - p.5 - ARHS.
  4. Railway Gazette International - p.43 - January 1998.
  5. Tramways & Urban Transit - March 1999.
  6. Railway Gazette International - p.351 June 2003.
  7. C J Wansbeek in Tramways & Urban Transit June 2003.
  8. Tramways & Urban Transit - March 2003.
  9. Tramways & Urban Transit - May 2002.
  10. Tramways & Urban Transit - January 2003.
  11. Tramways & Urban Transit - June 2001.
  12. Railway Gazette International - February 1999.
  13. Railway Gazette International - December 2002.
  14. Railway Gazette International - June 2003.
  15. Local Transport Today - 7th November 2002.

Discussion Document 006: top of page

Prepared by F A Andrews - for the LRTA Development Group - July 2003.