ABSTRACT
Limehouse Link is a major highway tunnel in London’s Docklands. The prime objective of using the observational method (OM) at Limehouse was the complete elimination of the extensive heavy steelwork for the mid-height propping system. The conditions in the Basin were so radically different that the application there effectively constitutes a separate case history for the OM. The key to unlock the constraints to agreement for implementing the OM lay in the resolution of the complexity of the soil/structure interaction with the simple introduction of a physical gap. The OM was introduced at the start of the first tunnel construction front in Ropemakers Fields. Stimulated by the success of the OM in the top-down construction, consideration was given to the potential for reducing the temporary works in Limehouse Basin. Design, particularly for the OM, has an important conceptual element. The designer needs to be adequately conversant with the specific construction methods and sequences and the progress on site.
