Observational method looks set to cut city building costs

Construction of a new 20 m deep commercial building basement in the centre of London involved what is believed to be the first true application of the ‘observational method’ on a major building project. Use of the ground movement monitoring technique, previously confined to civil engineering projects, allowed the top-down construction sequence on this confined urban site to miss a floor. This made it easier to remove the large concrete base of an existing basement and cut 20 weeks off the construction programme. All observed ground movements were within preset limits, so contingency measures were not needed, resulting in a highly cost-effective solution that could have wide application in the building sector.