New Spaces for Mobility: diverging trajectories within the Liège-Aachen diffuse city


  • Cédric Wehrle University of Liège


diffuse city, urban morphology, automobility, post-car policies, transborder relations




A rich body of research has been done on the many types of contemporary diffuse cities around the world (Barcelloni Corte and Viganò 2022), whose specific characteristics arise through specific geographic, but also social, technical, and political factors. The Liège-Aachen metropolitan axis is such an example of diffuse city, sharing common geography, culture, and history.

The Liège-Aachen metropolitan axis fits on many aspects within the research lineage on the diffuse city but sets itself apart from neighbouring western European examples in several ways. Firstly, it lies both at the centre of Europe and at the edge of two countries, languages, and planning cultures. Secondly, it crucially lacks a hegemonic urban centre of which this case study can be seen as the hinterland. Lastly, despite being part of the oldest recognized European cross-border collaboration, it lacks a common territorial project.

The socio-technical system of automobility (a term coined around the same time as research around the diffuse cities grew manifold), constitutes a defining catalyst not only for accentuating already present dispersed settlement structures, but also for producing, within a very short time span, characteristic urban forms and a sprawling new typological catalog of spaces linked to the car.

To accompany the massive urbanisation process induced by the car, two radically different planning traditions have been pursued between Liège and Aachen since the 1960s: the banlieue radieuse ideal was accentuated in Belgium (De Meulder et al. 1999), while the German area became a laboratory for Christaller's central space theory (Bloetvogel 2004). This results in very different settlement patterns between two regions, despite them sharing similar metrics of population growth, economic fortunes, and car adoption rates.

The strive to dramatically reduce carbon emissions linked to transport by 2030 constitutes one further instance of such shared metric. Accordingly, European countries and regions have, accordingly, published in recent years bespoke objectives and spatial planning tools to reduce car use. Conversely, in the scientific community, a growing body of work is being collected to envision post-car future scenarios in which the prevalence of the automobile (today recognized as a largely counterproductive system) and its ancillary spatial imprint would dramatically shrink in favour of new territorial configurations (Cogato Lanza et al. 2021). Many researchers have highlighted the crucial role of how spaces of automobility will be used as an essential leaver for change (Bertolini 2022), considering what is already there as a potentially formidable resource of grey energy.

This contribution aims to address this gap in the research about this very type of transborder diffuse city through the lens of automobility and a future post-car discourse. Specifically, it proposes, in the light of the scientific work describing either Belgian or German past planning practices, to compare the spatial impact of existing policy objectives and government plans being drafted today in both regions to reduce future car use. This comparison of two bordering, immensely comparable yet surprisingly contrasting contexts, aims to highlight possible paradoxes, but also opportunities for better informed transborder collaboration.

In 2021, violent floods in both Germany and Belgium highlighted how geographically inherent territorial solidarities is ever more a crucial factor for understanding our territories in a way that is meaningful to tackle the challenges of the transition. However, as there is not only one single path to a successful transition, different ways to spatialise the same metrics linked to automobility and its possible decline exist. For new solidarities between territories sharing common ecological threats to emerge, the implication of such diverging paths cannot be ignored.


Barcelloni Corte, M. and Viganò, P. (eds) (2022) The Horizontal Metropolis: The Anthology. Cham: Springer.

Bertolini, L. (2022) ‘Rethinking cities beyond mobility? A discussion’, CUS Working Paper Series [Preprint].

Blotevogel, H.H. (2004) ‘Zentrale Orte: Theorie, Empirie und Planung’, in Handwörterbuch der Raumordnung. 2nd edn. Hannover: Akademie fur Raumforschung und Landesplanung.

Cogato Lanza, E. et al. (2021) Post-Car World: futurs de la ville-territoire. Genève: MētisPresses.

De Meulder, B. et al. (1999) ‘Patching up the Belgian Urban Landscape’, Oase, (52), pp. 78–113.