The launching of the River Esk bridge, UK

The River Esk bridge carries the southbound carriageway of the M6 motorway over the River Esk estuary and forms part of the recently constructed M6 Carlisle to Guards Mill motorway extension, which provides the missing link in the motorway network between England and Scotland. The bridge is a 180 m long four-span steel composite viaduct. Due to site constraints the most economical and practical method of construction was to launch the steelwork into position rather than to lift the steelwork in by crane. The bridge steelwork, weighing over 800 t, was assembled on the northern approach to the bridge and launched southwards over the River Esk estuary. This paper demonstrates that the design and construction of a launched bridge can be significantly more complicated than the design of a comparable bridge that is constructed using conventional methods and that there are many more load cases and construction details to consider. This paper covers the approach for carrying out the analysis, design, detailing and construction of the structure and focuses specifically on the key issues relating to launching steelwork.