Extension of the U5 Europaviertel metro line, Frankfurt am Main
|Company||PORR GmbH & Co. KGaA . Structural engineering Branch Düsseldorf|
|Principal||U5 Europaviertel consortium|
|Location||Frankfurt - Germany|
|Type||Rail and road tunnels, Construction pits|
|Runtime||05.2017 - 01.2025|
Entire value chain for a complex infrastructure project from a single source
An approximately 2,750m addition to metro line 5 will connect the new Europaviertel development on the site of the former main freight station to the city’s underground rail network. In 2017, the U5 Europaviertel consortium, comprising PORR’s civil engineering and tunnelling divisions with PORR subsidiary Stump-Franki Spezialtiefbau, was awarded the contract for the construction of a 1,160m-long underground line section – including a connection to the existing U5 line – as well as the construction of an emergency exit at the junction point and structural work for the Güterplatz underground station. The new underground rail station will be constructed using open-cut tunnelling methods. The underground line will be routed from the tunnels to the surface via a ramp structure near Europa Allee using both underground excavation and open-cut tunnelling methods.
A project driven by a pioneering spirit
A tunnelling shield was used to drive the two tunnel tubes – 827m long on track 1 and 842m long on track 2 – in the underground tunnel structure: a first for this Hessian metropolis. The tunnel boring machine EVA, short for “Europaviertel anbinden”, weighing in at 580t and measuring 80m in length, had been specially adapted to the geological conditions along the route.
The south tube was excavated between September 2019 and September 2020. Equipped with a new shield casing and cutting wheel, EVA began driving the parallel north tube in January 2021 and reached its final position in May 2021. During the advance sequence, the machine assembled a total of 8,358 segments for the supporting concrete pipes.
Challenging work in compressed air conditions
Drill and blasting methods were used to complete the last few metres to the existing underground tunnel at Platz der Republik by July 2022. The air pressure at the construction site was increased to the same pressure as the groundwater using technically complex air locks to prevent water from penetrating the site. The PORR tunnelling division worked in 24/7 shifts to construct 11m of tunnel in the south tube and 3m in the north tube. Occupational health and safety were given top priority, so everyone had to undergo a health check-up as a precautionary measure. The work was carried out in three six-hour shifts per day. It also took another 1.5 hours to get the team in and out of the pressure chamber.
Excavating one of the deepest construction pits in Frankfurt
Excavation work for the Güterplatz underground station began below the first bracing level in August 2022. The construction pit will be around 170m long, 25m to 30m wide and excavated to a depth of 24m. The excavators are fitted with telescopic deep-reach booms to enable them to work at this depth. The works are accompanied by geotechnical monitoring. Roughly 170,000t of excavated soil have to be disposed of – an enormous logistical challenge in Frankfurt’s city centre.
You can find many fascinating videos about the construction of the extension of the U5 light rail line in Frankfurt here: Extension of the U5 Europaviertel - porr.de
Slurry trench wall work near the start excavation pit© Klaus Helbig
Slurry trench wall work near the start excavation pit. The slurry trench wall gripper excavating the slurry trench wall.© ARGE U5
Photo: Tunnel-boring machine with the cutting blade in turquoise. The tunnel-boring machine is still on the factory grounds and will be taken to the construction site soon.© Klaus Helbig