Working platforms -To BRE or not to BRE is the question

The Building Research Establishment (BRE) produced a practice guide for working platforms for tracked plant, which has become a “standard” in the industry in the absence of any other widely published simple design method. The BRE design method does not apply for thick platforms or for soft subgrades, but continues to be used in those applications in the absence of an alternative document. A case study is discussed which applies the BRE in such a situation, but then compares with alternative methods to assess the required working platform. Additionally a stochastic approach is used with the BRE method, given its sensitivity to the material strength parameters input, to provide a risk understanding rather than a factor of safety approach which does not define the risk explicitly. The derivation of the parameter inputs is discussed to show how assumed values for preliminary design and measured values produce different design platform thickness. Given the consequences of a failure, a construction control proof roll testing was used with deflection criteria. The derivation of this criterion is presented.