Significant expenditures of time, money and resources, both human and material, are wasted each year as a result of inefficient or non-existent quality management procedures. In an attempt to improve their market competitiveness, by limiting the extent of non value-adding activities, some organisations are beginning to monitor the performance of internal and external engineering and construction processes. To achieve these bold aims, these organisations are looking to other industry's such as manufacturing to examine the effectiveness of measuring and monitoring tools such as six-sigma. Only in recent years has the six-sigma method been utilised by some of the major players in the construction sector. To familiarise both researchers and practitioners on how to implement the six-sigma method and its potential benefits, the paper describes the outcomes of a six-sigma Process Improvement Project (PIP) conducted for the construction of concrete longitudinal beams on the St. Pancreas raised railway station in London, United Kingdom. The outcome of the six-sigma PIP was the improved productivity of beam construction, enhanced interaction between project teams, and reduced project delays. Moreover, interviews with key project participants were conducted to determine the success factors, barriers, suitability, and advantages of the six-sigma approach compared with other TQM techniqes. In summary, the six-sigma approach provided the PIP team with a structured process improvement strategy to reduce waste and other non-value adding activities from the construction process.