Renovation of Glenner railroad bridge RhB, Ilanz

Initial situation

The ravages of time gnaw at all buildings. Only through careful maintenance can the building fabric be preserved. This also applies to the Rhaetian Railway mountain line. Difficult topographical and geological conditions had to be overcome during its construction. Operation can only be guaranteed through suitable safety measures and extensive conversion and reinforcement work.

Due to the constant wear and tear on the tracks, maintenance work on the substructure and superstructure, minor repairs, careful maintenance of the ballast bed and tracks, as well as monitoring of the numerous avalanche and rockfall barriers and river obstructions are unavoidable.

In this context, the track systems and Ilanz railroad station will be comprehensively renovated from 2016 to 2018. This also includes the Glenner Bridge at the connection to Ilanz station. As train traffic will run over four tracks at the station in future, the Glenner Bridge is to be renewed.

The Glennerbrücke railroad bridge is a reinforced concrete composite bridge and was put into operation in 1960.

The track bed of the bridge is to be renewed. In order to keep the closure time as short as possible, a concept is needed that allows the construction work to be carried out within one night and the bridge to be reopened for rail traffic the next morning.

Solution and assessment

Concretum^® Q-FLASH 2/20 rapid-hardening concrete was used to renew the track bed. Despite very heavy rainfall during the concreting work, a strength of 20 N/mm2 was achieved within two hours of the start of setting.

As there was no cement silo available at the nearby concrete plant, the 15 m3 of concrete was produced on site in three truck mixers.

The construction time could be extremely reduced with the help of the quick-hardening concrete compared to the construction time with conventional concrete. The bridge's closure time was reduced to a minimum. The fresh concrete consistency was ideally adjustable, so that installation with a concrete pump was no problem. The strength development worked without any problems despite low temperatures and extreme precipitation.