Analysis and Design of an Overhead Self-launching Movable Scaffolding System for Arsta Railway Bridge, Sweden

摘要

Norwegian specialist, NRS AS, has been appointed by the contractor of Swedish TrafficAuthority, Pihl, to undertake the design and supply of a Self-launching Movable ScaffoldingSystem (MSS) for the construction of the Arsta railway bridge in Sweden. The bridge willbegin north of Arstaberg station and end just south of Alvsjo goods station. The railwaybridge is a single viaduct, pre-stressed solid concrete box-girder bridge. Bridge span lengthvaries from 24.67-34.22m with the average span weight of 20.0 t/m. There are two types ofpiers, i.e. single and portal, standing up around 10 meters above the ground. The 1.4km longbridge is cast in the MSS – a mold that is moved forward bit by bit until the casting process iscompleted. The 75m MSS is mounted on the piers that are in the area immediately south ofAlvsjo freight rail yard. The scope of the work includes the design, steel fabrication, andsupply of ancillary equipment for the MSS. This paper presents several design challenges dueto site constraints and the bridge structures itself. These challenges include high impact loadson the MSS due to adverse wind load anticipated while working nearby the moving train,special considerations to ensure efficient installation, bridge concreting and launching of theMSS.