Construction site in the heart of Zurich

The construction site is tucked between the Limmat, Hardbrücke bridge, and the busy Hardturmstrasse street. Phase 2 of the “Neu­bau Tram­depot und Wohn­siedlung Hard” con­struc­tion project has been under­way here since June 2021. The existing street­car depot, which is a listed building dating back to 1912, will be partially re­novated. The ex­tension building with a state-of-the-art depot hall is being built directly next to it. In the future, this will contain staging, main­tenance and repair areas, and operating and service rooms of the Zurich Transport Authority VBZ. Two four-story basement/­townhouses will flank this new hall to the south and north, providing space for both commercial and residential uses. In addition, two high-rise buildings with a total of 22 and 23 floors, respectively, around 70 m high, are being built. Space to provide a variety of uses for the residents of this new de­velopment is to be de­veloped in the court­yard between the town­houses and the high-rise buildings, above the pre­stressed ceiling of the depot hall.

A number of different de­partments from Marti Zurich have been working here since the summer. As part of construction phase 1, the special civil engineering de­partment has already installed over 100 bored piles. Around 50 of these piles each provide support for the area of the future high-rise buildings. Each of the three cranes will also be sup­por­ted by four piles. A building main­tenance team is al­ready working on re­pairing the old depot hall. They are ex­cavating the existing floor, con­structing escape tubes for the residential structures, and will then build a new base­plate. All the service lines in this listed hall must also be re­novated. The building con­struc­tion makes up the largest part of the project. Here, work on the inner base­ment lining is in full swing. A new mobile rotary distributing unit is used for pouring concrete here. It can be re­located on the con­struc­tion site as required and offers additional versatility. A street­car pit is currently being in­stalled in the base­ment of the new depot hall. This will make it possible to service the street­cars from below in the future. The base­ment floors of the base constructions and high-rise buildings are being constructed in the flanking areas. In the base­ment of the high-rise buildings, the unusually high pro­portion of re­inforcement and massive wall inter­sections are especially striking.

Marti Zurich’s BIM team had produced a model of the structure to prepare the offer prior to the active con­struc­tion phase. This working model was also ex­ceedingly help­ful for the ensuing work pre­paration, the quantities ex­tracted, and the construction sequence and logistics planning. After all, forward planning is crucial here. In addition, there are still major logistical challenges to be tackled at the con­struc­tion site. The adjacent Hardturm­strasse is one of Zurich’s busiest roads, which constrains delivery options and times. In particular, the delivery of sand, cement, and gravel for the concrete plant has to be timed almost down to the minute – a difficult under­taking for truck drivers in the middle of city traffic.

The last street­car trips from the Hard streetcar depot took place at the end of January 2021, after which the gates were closed. In 2025/26, the project is scheduled to be completed and the new street­car depot will be ready for service.