Barcelona’s ambitious public transport expansion reached a critical milestone in the early hours of Thursday morning. The colossal cutting wheel of a tunnel boring machine (TBM) arrived at its launch site on Gran Via. This component, the machine’s operational heart, completed a complex overnight journey to the Eixample district, setting the stage for summer drilling.

This arrival significantly advances the €412 million project to extend the L8 line of the Ferrocarrils de la Generalitat de Catalunya (FGC). The extension will create a vital four-kilometre link, connecting the Llobregat-Anoia and Vallès-Sarrià FGC lines beneath the city. The Generalitat’s timeline anticipates the unified service will operate by 2030, transforming commutes for an estimated 19.5 million passengers annually.

A Major Step for Barcelona’s Metro Network

The project aims to bridge a historical gap in the city’s rail network. Extending the L8 from Plaça d’Espanya to Gràcia will create a seamless FGC connection across the city. The plan includes two new Eixample district stations: Hospital Clínic, providing an interchange with the L5 metro line, and Francesc Macià, connecting with the Trambaix tram system. Additionally, existing stations at Plaça d’Espanya and Gràcia will be significantly remodelled and expanded to accommodate increased passenger flow.

Department of Territory, Housing, and Ecological Transition officials confirmed the machine’s arrival, noting that preliminary work at the Gran Via shaft is advancing as planned. This project is one of several major infrastructure works currently underway in and around the city, often requiring careful traffic management. For example, the H12 bus route on Gran Via has already been diverted due to construction.

The Overnight Journey

To minimise traffic disruption in Barcelona, the TBM’s central cutting wheel travelled under the cover of darkness. The special convoy departed from a maintenance site in Sant Boi de Llobregat at 11 p.m. on Wednesday. There, the machine had undergone inspections and refurbishment. Previously, it excavated new rail access tunnels for El Prat Airport.

La Vanguardia reported that the convoy travelled along the C-31 motorway to Plaça Cerdà. It was then rerouted through the Zona Franca and the Port de Barcelona, bypassing sections of Gran Via where it would not fit. It re-entered the city’s main thoroughfares at Plaça Drassanes, ascending Avinguda del Paral·lel and Carrer d’Entença before reaching its Gran Via de les Corts Catalanes destination around 3 a.m. on Thursday.

Assembling the Subterranean Giant

Although the cutting wheel is the most visually striking part, it represents just one component of the enormous tunnel boring machine. Over the coming months, teams will assemble the full machine inside the deep launch shaft. It will measure nearly 100 metres in length and have an excavation diameter of 10.6 metres. Once assembled and commissioned, the machine will begin its 13-month journey towards Gràcia.

Concurrently, a smaller micro-tunnelling machine will create a gallery from the Gran Via site to the nearby Parc de Joan Miró. This conduit will house a conveyor belt system, transporting tonnes of earth and rock excavated by the main TBM. The soil will be temporarily stored in the park, then removed by lorries via Carrer de Tarragona. This logistical solution aims to reduce heavy vehicle traffic on Gran Via.

Looking Ahead to 2030

While the TBM’s arrival marks a major milestone, work continues across the entire project line. Construction is ongoing for future stations and essential infrastructure like emergency exits. However, the project has faced setbacks. 20 Minutos reported that an archaeology service strike led to a four-month pause in work on an 85-metre-deep emergency shaft on Carrer Muntaner; work only resumed in January.

The L8 extension forms a cornerstone of the Generalitat’s plan to enhance sustainable mobility in the metropolitan area. Consortiums led by construction giants Ferrovial and Sacyr are undertaking the project, which is crucial for reducing road congestion and improving air quality. This project follows other major tunnelling works in the city, including the ongoing L9 metro line, whose TBM recently reached Sant Gervasi en route to Lesseps.