Tough terrain does not stop Stuttgart’s success

Stuttgart is a city built on many hills and this results in countless stairs and slopes. Organising public transport in a place like this means you have to be careful not to end up running a network like a rollercoaster!

traffic control

Providing safe, fast and reliable public transport for the people of Stuttgart means a network of bus lines and rail lines winding their way through valleys, up and down slopes and even right through the rock if necessary.

The network also has to take into account the ever-increasing road traffic in the city which struggles to negotiate the very same problems. This is the situation that Stuttgarter Straßenbahnen (SSB) has found themselves in for over 140 years, and so far we feel we have made the best of it. After all, today SBB is operating a successful network with 900km of routes.

Two thousand seven hundred employees at SSB provide an integrated public transport service by bus and rail to roughly 600,000 passengers a day, covering an area of 591km2.

After conducting several surveys, public transport was found to be one of the three finest features of the city for Stuttgarters, and SSB are a vital contribution to the highly ranked quality of life in the city.


In 1961, SSB decided to go underground. Seventeen years later, the inner city roads, the historic quarters and the main shopping and pedestrian areas were completely relieved of street-level tram-traffic. In 1976 the concept was taken further, and in 1985 the first light-rail line U3 used its brand-new standard-gauged track leading overland from Vaihingen to Plieningen. Gradually, SSB switched line-by-line from tram to light-rail, using three-railed tracks for decades to ensure that during the process both the meter-gauged tram-vehicles, as well as the standard gauged light-rail, could be operated simultaneously.


Light-rail in Stuttgart means a new network, separated from road-traffic where possible and with as little street level crossings as possible. This independence is gaining two important goals: a higher safety level and competitive speed.

Tunnels are a characteristic feature of this new system of tracks. Twenty-four kilometers of them no longer simply cross under the busy city centre, but also short-cut the steepest gradients and by-pass the narrowest streets and valleys. Consequently, quite a number of stations, even in the suburbs, are underground stations. Considering the architecture of the early underground stations in the city centre, SSB decided that a new philosophy and friendlier aesthetics would better meet passengers’ needs of subjective security and well-being. Installing light chimneys to provide as much daylight as possible, and locating stations at the mouth of tunnels or installing elongated ramps will help to achieve this goal.

An urban rail-system with tracks independent from road traffic is still an obstacle to pedestrians. Stuttgart has developed a special kind of intersection called ‘Z-crossing’, flanked by flashlights for the safety of passengers. In right-handed traffic, ‘z’ is the course the pedestrians have to pursue across the tracks, always forcing them to cast their view and attention into the direction of possible oncoming trains.

The traffic within the network is run by ITCS (Intermodal Transport Control System). The centrally located system communicating with on-board-units, tracks and signals was fundamentally introduced in 1990 and brought up to a new standard in 2006. It combines live data of all vehicles and automatically induced safety of dispatch and regulation of traffic.


Light-rail in Stuttgart also means new vehicles. To service the steep Stuttgart hills and the equally increasing number of travellers in the 1960s, SSB and Maschinenfabrik Esslingen custom-developed the GT4 tram for Stuttgart. Badmouthed as being too big, too loud and too ugly on its first appearance in 1959, these vehicles were tearfully yet cheerfully waved goodbye as cozy, cute and classically beautiful in 2008 when parading on its final round. Today, its equally dominating successor in 1985 was a high-powered bi-directional light-rail train with all axles driven called DT8 (bi-directional vehicle on eight axles). Custom-designed to master gradients of up to 8.5% – unmatched in Europe on a standard gauge – the DT8 not only provides a more powerful traction motor than usual when travelling up, but it also owns powerful breaks when travelling down. The Stuttgart coaches function as a generator, feeding the energy produced while breaking back into the 750 Volt overhead contact line. However, the 38m-long DT8 was also designed for passenger comfort with a large number of upholstered seats, air-conditioning and large windows. Visibility, cheerful colours, one level floors, intercom connection to the driver, closed circuit recording surveillance, well lit interiors, clearly marked buttons and devices, as well as the well preserved absence of vandalism, junk, scratching or paintings are features SSB refined from the very first prototype and in several generations and transformations of DT8 as a contribution to the security or subjective security of our passengers.

One hundred and sixty four DT8 vehicles of different technical generations form SSB’s light-rail fleet today, the oldest set of them having been in service for nearly 25 years. The pressing question of replacement – whether to order a new set of custom-built trains or to try a new vehicle – was resolved in 2007 with a cour­ageous answer. Sixty of the older DT8 vehicles are to undergo a complete overhaul inside SSB’s very own workshops and using our in-house expertise, are expected to last at least another 20 years. Today, over a dozen of the renovated trains are already back on the tracks. The programme aims to refurbish 12 trains a year. However, as even then the existing fleet would not provide enough rolling stock for the extended network of the future, an order of an additional 20 DT8 vehicles has been placed.


In the early period of mixed operation, the DT8 as well as the GT4 tram accessed street-level stations by steps or folding steps. While developing the light-rail-system, SSB raised the level of accessibility for handicapped persons, prams, wheelchairs or heavy luggage station-by-station. Quite out of focus in 1985, it is still not possible to use low-levelled trains in Stuttgart: there simply are no suitable solutions as yet of how to fit the high-powered motors indispensable to climb up, and break downhill, into a light-rail vehicle. Stuttgart’s stations therefore are, and will be, clearly recognisable by their elevated platforms. The earliest underground stations date back to the 1960s, when accessibility for persons with restricted mobility was not a great concern, and so these have been refitted with elevators. Platforms exclusively serviced by light-rail were raised to the level of the coaches, accessible by ramps and stairs. Major stations each offer an elevated and a ground-level platform during periods of mixed service. For 2010, this rigid programme leaves SSB with merely two street-level stations waiting to be rebuilt. By 2011, all the folding steps will have been banned. The DT8 trains can run in double traction and do so for example on the busy U6. In 2006, SSB’s U11 had to accommodate over 100,000 international supporters to the stadium for the Football World Championships. In order to offer them maxi­mum space in double traction trains, SSB started elevating the abandoned ground level platforms along the route in order to extend the neighbouring elevated platforms, as preconceived and prepared when they were first constructed in the 1970s.

Innovation and service

SSB are undergoing a process of restructuring to meet the strict requirements of the city of Stuttgart concerning the limitation of its annual subsidies to a maximum of €25 million. So far, SSB have been successful in meeting this requirement under the accordance that the customers should not notice. SSB remain convinced that improved service and innovative techniques are the way to cover costs and for the future of public transport in general. The SSB Diesel-fleet is a flock of 270 standard and articulated buses, mostly Mercedes-Benz Citaros, although among the newest arrivals are a handful of overlong Mercedes-Benz Capacitys. Buses are a field where SSB are traditionally partners in testing new technology. One of the most noticed projects in recent years has been a Fuel-Cell-Bus by Ballard and Daimler.

Protecting the environment is one of the major motives of SSB to pursue innovative technology, but not the only one by far.

Focusing on passenger’s needs and comfort has proven to win SSB customers; for example in the design of vehicles and stations, for example in augmenting the overall travelling speed, and convincing Stuttgarters that using a car and public transport can be gainful for their mobility. A dynamic passenger information system (DFI) has been in service at all the major stations since 1993. It not only announces the next due trains, but also the time until their arrival. It is also a means of acute and regular passenger communication in addition to audio information. Since 2009, the displays have been offering real-time information. These days, SSB are running tests for a similar real-time passenger information system on screens inside the coaches. However, it is not only through technology that SSB try to constantly improve their service. Just to mention one of the pioneering ideas: for 10 years now, SSB have given their passengers a guarantee on mobility and service offering, for example, the reimbursement of cab-fares should a train or bus be more than 20 minutes late, or the organisation of a taxi service at night, even offering to pay a share of the fare for women travelling alone at night or offering irregular bus stops on request at night. Through this, SBB are also aiding security in public transport.

Future extensions

Dating back to the days of the tram, the Stuttgart lines can still be divided into three categories; lines along the (main) valley of Stuttgart, lines traversing the valley and diagonal lines. While transforming the tram system into light-rail, many new lines have been built or extended as well, never changing this principle. With the termination of the northern branch of the U15, the last and most challenging of the former tram-lines, in the coming winter of 2010 the transformation will be complete. It has taken two years to construct 3km of track and about 1km of tunnel to service the northern quarters of Stammheim and Zuffenhausen by light-rail.

Once the U15 northbound is open, development of the rail system will by no means have come to an end. At about the same time, SSB will open the 3m-extension of U6 running south connecting the industrial area and residential quarters of Fasanenhof, including yet another 1km of tunnel. The annual adaption of the schedule by the end of 2010 will bring forth major changes in the network of routes, lines and destinations of the SSB. All these are merely heralding the effects of the so called S21 project by Deutsche Bahn on the activities of SSB. This extensive conversion of Stuttgart main station and adjoining quarters requires SSB to relocate two underground sections including a station, and also to construct the light-rail line U12 designed to service the reconstructed area of S21. Building U12 will again mean extensive track and tunnel construction.

About the author

Reinhold Bauer has been working in public transport in the Stuttgart region since 1968. This was when he joined SSB as a clerk, to eventually work as assistant to the management, and in various other positions, acquiring a university degree of economics at the same time. Between 1978 and 1996, Mr. Bauer worked for the Verkehrs- und Tarifverbund Stuttgart (VVS) and then changed from the Board of Management of VVS to the Board of Management of SSB.