Hamburg, 17 July 2025 – The U5 underground railway line in Hamburg is a showcase project. The new transport artery through the Hanseatic city will connect the outer districts in the east and west with the city centre – and do so in the most climate-friendly way possible. Hamburger Hochbahn AG and its subsidiary HOCHBAHN U5 Projekt GmbH have set themselves the goal of breaking new ground with the construction of the U5 and placing responsibility for climate protection at the heart of their planning and construction work.
© Hochbahn
For the first time in an infrastructure project, not only the CO2 emissions generated on site during construction are taken into account, but also the entire supply chain of the building materials.
ArcelorMittal's XCarb® recycled and renewably produced reinforcing steel has a significantly lower carbon footprint and is therefore ideal for use in this flagship project. The 1,100 tonnes of XCarb® recycled and renewably produced rebars from ArcelorMittal are produced in an electric arc furnace from recycled material using 100% renewable energy. This means that emissions are around 300 kilogrammes of CO2 per tonne of finished products, compared to around 2570 kilogrammes of CO2 per tonne for steel produced conventionally in a blast furnace, which corresponds to a reduction of more than 88 per cent. The CO2 reductions are recorded and certified via an Environmental Product Declaration (EPD)[1].
“For the U5, we have set ourselves the goal of reducing CO2 emissions by 70% during the construction of the new underground line. To achieve this, we are looking at the entire supply chain for our building materials, among other things. In our tenders, we only request environmentally friendly materials. ArcelorMittal is one of the suppliers whose end product has significantly reduced CO2 emissions through the use of recycled scrap and green electricity. This means that the U5 can also serve as a model for other public construction projects,” emphasises Klaus Uphoff, Technical Director of HOCHBAHN U5 Projekt GmbH.
“Price should not be the only criterion in public procurement. It is positive that sustainability has been meaningfully integrated into the procurement process for the construction of the U5. More projects like this are needed to establish CO2-reduced steel in public and private construction projects in the long term,” comments Joachim Scheibe, Managing Director of ArcelorMittal Commercial Long Germany.
[1] https://constructalia.arcelormittal.com/files/XCarb%20Recycled%20and%20renewably%20produced%20Reinforcing%20steel%20in%20bars%20and%20coils--e79fb1adbe3110be5550c5e1eb017ae7.pdf
