One of the oldest railway lines in France was opened in 1839 between Mulhouse and Thann. In 2007 it will be connected to the urban tramway network of the Mulhouse region. This connection will allow trams to switch between the urban tramway network and the suburban train network. The tram service on this 39,5 km long interconnecting line is run by the Regional Council of Alsace (the organising body) and involves a very extensive co-operation between the French rail network authority (Réseau Ferré de France, RFF), the national French railway company (Société Nationale des Chemins de Fer - SNCF) and the Mulhouse district transport authority (Syndicat Intercommunal de Transports de la Région Mulhousienne - SITRAM).

With a dense urban web around the city and outskirts of Mulhouse, southern Alsace includes several small towns of the Plain of Alsace and urban areas spawned by the spreading of Mulhouse industry into the Vosges valleys.

The density of the urban web responds to the density of the rail network. A five-branch star culminates in Mulhouse. Each branch is a potential link to the future tramway network of the Mulhouse urban district (service scheduled in 2005). In 1996 the Mulhouse district transport authority (Syndicat de Transports de la Région Mulhousienne - SITRAM) started feasibility studies for an urban public transport project and investigated a possible link-up of urban and railway networks. The Karlsruhe region in Germany served as example. In 1998 the principle of an initial network with two urban tram lines connected to a third suburban "tram-train" line was chosen. This line is a first step towards a more extensive suburban network that could extend into southern Alsace.

Apart from the towns which form part of the Mulhouse urban district and are included in the Urban Transport Perimeter (population of 215,000), the interconnecting line offers a transport corridor for a population of 52,000 inhabitants. This corridor is made up of two urban areas (Wittelsheim and the Thann-Cernay bi-pole) located at the mouth of the Thur valley and an urban continuum stretching along the valley between Thann and the village of Kruth. The line will have 21 suburban stations and 7 stations on its urban section. Two of these will provide connections with the two other lines in the urban network.

The perimeter of service includes the urban zones of the Lower and Upper Thur Valley with a population of around 25,000 living along existing communication axes of railway and trunk road. From the town of Thann, all road transport passes through this route: micro transport services, urban travel, traffic between the Mulhouse urban district and the Lorraine area, including national and international transit between Luxembourg and Basel. This gives rise to problems of pollution, safety and systematic congestion, even though HGV (heavy goods vehicle) traffic has recently been re-routed. The road, a mainly urban stretch, carries a daily average of approximately 23,000 vehicles upstream from Thann.

In 1999 the available railway infrastructure, not very efficient considering the congestion of the trunk road, carried an average 2,300 passengers a day. This was an obviously low percentage of the modal-split. Inter-urban coaches, mainly used for school transport, carried 2,250 passengers per day. As of 2000, new rail coaches were added to this line on the initiative of the Regional Council within the framework of the French rail transport regionalisation programme, pushing up passenger figures by 2/3 in just two years.

In 2007, the new interconnection will offer a decisive improvement to the transport service. Existing railway coaches will be replaced by interconnecting coaches, which will offer better service and lower costs while improving scope and passenger numbers. In parallel, several improvements to travel conditions will make the service more appealing, placing the project at the heart of a more general reorganisation of transport:

• Inter-urban coach lines will be re-routed towards "tram-train" stations;

• parking lots of park + ride facilities along the line will be doubled in size and number;

• SNCF stations and their surrounding areas will be developed by local authorities with the support of the Regional Council of Alsace;

• access to stations for private cars, bicycles and pedestrians will be improved or created.

• upgrading of public space will be supported by the urban integration of stations and town extensions, making the line more appealing (e.g.: nature and localisation of property development programmes);

• other local development factors are also envisaged by local players, such as developing the tram-train project in line with tourism development policies (tourism signage systems, tourist shuttle services).

The effect of these dynamic forces will increase daily passenger numbers to 12,000, thereby doubling the 1999 figures. This rise will ease road traffic in urban sections. The modal section of public transport will then reach 13% for the suburban part of the line.

Public transport projects on segregated sites affect a user’s sense of space. With the opening of the interconnecting line, the valley will move from an interurban service (trains/coaches) to a "semi-urban" mode. Users of the valley will have a direct connection, without having to change, to the urban area of Mulhouse, its university campus, its collective facilities, its employment areas, services and the heart of its city centre. The already strong links forged between the valley and the surrounding area of Mulhouse will be strengthened. The change of status of the line will have a series of impacts, which will modify user perception of places: firstly, the integration of the valley into the same transport organisation area will offer greater general mobility along with the advantages of co-ordinated times and prices. This change will be accompanied by changes in urban semiotics: the rolling stock will be urban, stations will be designed for the first time in order to integrate high quality standards into the urban context, steps will be taken to develop surrounding areas and access to stations. There will also be new stops for a more proximate service. New urban furniture will appear as well as new signage systems within the urbanised area and within the stations. All these factors will be considered as the suburban adaptation of the urban tramway. There will be a higher percentage of commuters and the "tram-train" will also provide a "city" transport service for passengers using it for other reasons: leisure, shopping, tourism… Gradually, these transformations will change the users’ very perception of the territory.

These predictable changes will not be the only consequence of the tram-train project. The project will cater for ongoing changes in users’ needs and behaviour. The urban district and the valley already do and will in future share the same local area more fully. The public will use it more and more for daily activities and travel. Supported by the growing emergence of these new territorial scales, the tram-train will provide a service designed to encourage greater use of public transport. This being said, the impact on user habits will be used to play a structuring role at the heart of the development and the special planning of the local territory.

The opening of tramway-services on this interconnecting line is an innovation in France. New too is the way in which it encourages debate on spatial planning and local development of suburban public transport. The extensive partnership, which it brings into play, makes it exemplary for local government: the project objectives resulting from the co-production of the many partners involved.