How construction sites are reshaping the way we experience urban environments

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The Transitional City

European cities are undergoing a profound phase of transformation, driven by investment in public transport infrastructure. Construction sites for new tramway and metro lines, as well as extensions of existing networks, now cut through historic centres, residential districts and peripheral areas, with the aim of making mobility more sustainable, accessible and equitable. In Italy, this process is particularly evident: hundreds of kilometres of new tram lines are currently under construction, reshaping the urban fabric of cities such as Bologna, Florence, Rome, Padua and Palermo.

This season of change, however, has an immediate impact on everyday urban life. Tramway construction sites, in particular, are not static or confined in space, but rather moving elements: they advance along streets, rapidly alter layouts and routes, and transform the urban mobility scenario within the span of months—sometimes even weeks. Their linear and progressive nature concentrates impacts over time, intensifying the perception of disruption and placing additional stress on transport networks that are often already fragile.

Unlike other major infrastructure projects, a tramway construction site does not merely occupy space temporarily. Once completed, it returns a street that is fundamentally different from what it was before.

Road cross-sections change, traffic circulation schemes are redefined, and priorities shift among different modes of transport. This dual nature—temporary in terms of construction impacts, permanent in terms of spatial outcomes—makes tramway works particularly significant when analysing mobility-related effects. During the construction phase, the system is subjected to high but short-lived stress; once the infrastructure is completed, the system must adapt to a new, stable configuration, which may generate benefits in the medium to long term but requires a necessary period of adjustment.
The construction site thus becomes a true transitional phase: an accelerator of change in mobility behaviours, an unavoidable step towards a new urban balance.

A city’s ability to absorb these impacts largely depends on its underlying structure. Larger, more redundant networks tend to respond with a general loss of efficiency; historic centres, by contrast, with their narrow streets and limited alternatives, are far more vulnerable and risk temporary fragmentation. This is precisely where one of the key challenges of the coming decade lies: managing construction sites not merely as technical works, but as processes of urban transformation, capable of guiding change while mitigating disruption and enhancing long-term benefits.

These thoughts were at the heart of the second edition of “NExTropolis. Metropolitan Evolutions”, the event organized by NET Engineering and dedicated to urban design. Below, we present contributions from some of our invited speakers: