SBB Railway Line Lenzburg, Rapid-Hardening Concrete for Critical Signal Foundations Under Live Railway Operations

Challenge

As part of infrastructure works on the SBB railway line in Lenzburg, signal foundations had to be constructed within very tight time constraints. The requirements for execution were demanding: all works had to be completed during short track possession windows while ensuring the necessary safety standards for the subsequent railway operations. For Walo Bertschinger AG, this posed significant challenges in terms of logistics, construction sequencing and material selection. Sufficient concrete strength had to be achieved within only a few hours after placement to allow the installation works for the signalling equipment to proceed according to schedule.

Solution

The project utilised Concretum^® Q-FLASH 2/20 rapid-hardening concrete technology. The concrete mix design was specifically tailored to the project requirements, providing controlled workability while achieving very rapid strength development. The concrete was mixed directly on site by our technicians using a truck mixer. The mixer arrived on site preloaded with aggregates and water. To minimise installation time, our rapid-hardening cement and admixture system were carefully dosed to ensure sufficient working time for conveying the concrete via the truck-mounted conveyor belt and placing it into the formwork. Throughout the concreting process, the concrete was continuously monitored. In addition to testing fresh concrete properties, strength development was verified directly on site. This ensured that the specified performance criteria required for the release of subsequent construction activities were reliably achieved.

The success of the project was the result of close collaboration between Walo Bertschinger AG, the consulting engineers, surveying teams, the specialists from Concretum and the Niederlenz concrete plant. Through the combination of meticulous planning, continuous quality control and high-performance rapid-hardening concrete technology, the demanding project schedule was successfully maintained.

Result

The construction of Signal Foundation 843 was particularly critical. After the onset of the setting process, the anchorage system was released under geodetic control and the foundation was monitored for any movement. The achieved early compressive strength of more than 20 MPa enabled approval for the subsequent works and the installation of the signal mast on the same day. The rapid strength development not only reduced track possession times to an absolute minimum but also created additional schedule reserves and enhanced execution safety for all parties involved.

The Lenzburg project clearly demonstrates the added value that modern rapid-hardening concrete systems can provide in railway infrastructure construction. Where every hour counts and track closures must be kept as short as possible, rapid strength gain, high process reliability and close technical support enable the efficient and on-schedule delivery of complex infrastructure projects.