Discussion: The design of temporary excavation support to Eurocode 7

Most would accept CIRIA C580 (Gaba et al., 2003) as a guide to previous good practice. The author’s conclusion that designs to Eurocode 7 give lower margins of safety than are recommended in CIRIA C580 is indeed surprising, and as he states is contrary to Eurocode 7 requirements. This may follow from the way that the so-called ‘single source principle’ is applied in the paper. Eurocode 7 (Clause 2.4.2) states that this principle may apply ‘in some situations’. Neither Eurocode 7 nor the UK National Annex (BSI, 2004b) describes these situations, but it is doubtful that designers may invoke it wherever they choose. Engineers should aim to apply the partial factors given in the National Annex in the way envisaged when they were set down. Unfortunately the National Annex does not tell us what this is.